Power consumption-based fan control for power over ethernet equipment

Abstract

The invention relates to power consumption based fan control of power over Ethernet equipment. A power sourcing device (PSE) of power over Ethernet (PoE) includes a PoE port connectable to a powered device (PD) via a communication link. The PSE also includes a power supply unit (PSU) to supply PoE power to the PD via the PoE port and one or more fans to provide airflow through the PSE, the one or more fans including at least a first fan to provide airflow to the PSU. The PSE also has a control circuit that includes fan control logic configured to monitor a PoE power consumption parameter indicative of an amount of the PoE power supplied by the PSU. The fan control logic is further configured to control a speed of at least the first fan based at least in part on the PoE power consumption parameter.

Description

[0001] introduction

[0002] Networking devices such as switches, routers, or access points typically have ports to which communication cables can be removably connected to allow data to be transmitted through the networking device (e.g., transmitted between two client devices coupled to the corresponding ports of the networking device). Examples of such ports include RJ45 ports, which can be connected to an Ethernet cable. In particular, some networking devices may be able to provide Power over Ethernet (PoE) on one or more of their ports, thereby allowing data signals and power supply signals to be transmitted through the same Ethernet cable. This can allow electronic devices that support PoE to be communicatively coupled to the network and receive power via the same cable, which can make the way the device is deployed more flexible (e.g., the device may no longer need to be located near a power outlet or no longer need to have a long power cable to connect to such an outlet). In a PoE system, a device that supplies power to other devices via PoE is called a power supply device (PSE), and a device that receives power from a PSE is called a powered device (PD). A PSE also typically acts as a networking element, such as a switch or router. A PD may also be a networking element (e.g., a wireless access point, a PoE repeater / hub, etc.), a network endpoint (e.g., a security camera, an Internet of Things (IoT) device, etc.), or any other electronic device with a PoE port. BRIEF DESCRIPTION OF THE DRAWINGS

[0003] Alone or with Figure 1 The present disclosure can be understood from the following detailed description. These drawings are included to provide a further understanding of the present disclosure, and are incorporated into and constitute a part of this specification. The drawings illustrate one or more examples of the present teachings and together with the description explain certain principles and operations. In the drawings:

[0004] Figure 1 is a block diagram illustrating an example PSE.

[0005] Figure 2 is a block diagram illustrating a first example fan control logic.

[0006] Figure 3 is a process flow diagram illustrating a first example method that may be performed by a first example fan control logic.

[0007] Figure 4 is a schematic block diagram illustrating a first example circuit for implementing aspects of a first example method.

[0008] Figure 5 is a table illustrating conditions, the comparator outputs resulting from those conditions, and the fan control schemes indicated by those comparator outputs.

[0009] Figure 6 is a process flow diagram illustrating a second example method that may be performed by the second example fan control logic.

[0010] Figure 7 is a schematic block diagram illustrating a second example circuit for implementing aspects of the second example method.

[0011] Figure 8 is a table illustrating conditions, combinations of comparator outputs resulting from those conditions, and fan control schemes indicated by the combinations of comparator outputs.

[0012] Fig. 9 is a block diagram illustrating a second example fan control logic.

[0013] Fig.10 is a process flow diagram illustrating a third example method that may be performed by the second example fan control logic.

[0014] Fig.11 is a schematic block diagram illustrating a third example circuit.

[0015] Fig.12 is a graph illustrating an example fan curve based on PoE power usage.

[0016] Fig.13 is a block diagram illustrating an example computer program product. DETAILED DESCRIPTION

[0017] Electronic devices such as PSEs generate heat when powered on and in use. Therefore, such devices may be provided with one or more fans configured to flow air through the components of the device to dissipate the heat generated by the device and cool its components. The more heat the device generates, the more airflow may be required to keep the components within the desired operating temperature. However, in some cases, providing too much airflow may also have undesirable side effects, for example, because higher fan speeds generate greater noise output and use more electricity. In some cases, the noise output may be quite high, reaching a level that is potentially annoying to users (this is particularly relevant to devices deployed in crowded spaces, such as access points or other networking devices deployed in campuses or office buildings). Therefore, in some cases, it may be desirable to reduce unnecessary noise generation by providing only the airflow required to fully cool the device. In addition, because the heat generated by the components of the device may vary over time and from component to component, the required amount of airflow may also change over time, and may be different for each fan if there is more than one fan. Therefore, some devices try to dynamically change their fan speeds in order to keep the fan speed as low as possible, thereby reducing unnecessary noise while still providing sufficient cooling under the current thermal conditions.

[0018] One method of dynamically controlling fan speed is to control fan speed based on the temperature sensed at one or more locations within the device. For example, a fan controller may determine a fan speed set point by consulting a predetermined function, often referred to as a "fan curve," that relates the sensed temperature as an independent variable to the fan speed set point as a dependent variable. The fan controller may periodically read the sensed temperature and then consult the fan curve to determine the next fan speed set point for the fan, so that when thermal conditions in the device change, this will be reflected in the sensed temperature and the fan speed may change accordingly.

[0019] However, using temperature sensors and temperature-based fan curves to control fan speed (hereinafter referred to as "temperature-based fan control") may not always be feasible or produce satisfactory results. In particular, not all PSEs are equipped with temperature sensors, and in such PSEs that lack temperature sensors, temperature-based fan control may not be used. In addition, even in those PSEs equipped with temperature sensors, sensing temperature may not be sufficient to set the optimal fan speed for cooling all components of the PSE. In particular, temperature sensors are typically arranged to sense the temperature of some components (or their vicinity), but not the temperature of other components. Because the heat requirements of some components may be different from other components, the fan speed that is optimal for the components whose temperatures are sensed may not be optimal for other components whose temperatures are not sensed. Therefore, there may be a situation where the components whose temperatures are not sensed may not be sufficiently cooled (i.e., the fan is driven too low) or may be overcooled (i.e., the fan is driven too high, resulting in unnecessary noise generation).

[0020] For example, a PSE may have one or more temperature sensors arranged to sense the temperature of a processing circuit or other control circuit (e.g., a processor, a switching circuit, etc.) of the PSE, but there may not be a sensor arranged to sense the temperature of a power supply unit (PSU) of the PSE. The thermal requirements of the processor / control circuit and the PSU may be quite different, because the heat generated by one may be largely independent of the heat generated by the other. More specifically, the heat generated by the processing / control circuit may depend largely on the amount of data communications transmitted through the PSE. In contrast, the heat generated by the PSU may depend largely on how much PoE power is supplied from the PSE to the connected PD. Therefore, there may be a situation, for example, in which the processing / control circuit is heavily loaded, many communications are transmitted through the PSE, and at the same time the PSU provides little PoE power to the PD. In this case, the processing / control circuit may generate a lot of heat, while the PSU generates little heat. In this case, if conventional temperature-based fan control is used, the fan may be driven at high speed due to the high temperature of the processing / control circuit, but this high fan speed may be much higher than the speed required to cool the PSU that generates little heat. As a result, the fan cooling the PSU generates unnecessary noise because it is driven at the faster speed required. Conversely, a situation may arise where the PSU is providing a large amount of PoE power to the PD while the processing circuitry is lightly loaded with communications. In this case, the PSU generates a large amount of heat while the control circuitry generates very little heat. Therefore, if conventional temperature-based fan control is used, the fan may be driven at a low speed due to the low temperature of the processing / control circuitry, but this fan speed may be too low to dissipate the large amount of heat generated by the PSU. As a result, the PSU may not be adequately cooled (its temperature may exceed its desired operating range) because the fan providing airflow to it is driven at too low a speed.

[0021] A solution to the above problem is to provide more temperature sensors for the PSE, which are arranged to sense the temperature of more components - in particular, sensors for sensing the temperature of the PSU are provided - and the fan speed control scheme is adjusted to utilize these additional sensor inputs. However, it is not always feasible to provide more temperature sensors for more components. In particular, in some cases, the cost of providing additional temperature sensors in the PSE may be too high and unfeasible, especially for some components such as PSU. Although the individual sensors themselves may not be very expensive, integrating the sensors into the system may require redesigning the system board layout and / or the PSU board layout, which may be quite expensive. Therefore, in some low-cost PSE devices, it may not be feasible to provide additional temperature sensors. In addition, existing PSE devices that lack sensors may be difficult and cost a lot to be converted to include sensors.

[0022] To address these and other issues, examples disclosed herein provide for controlling the speed of one or more fans of a PSE based at least in part on a measurement of PoE power usage (e.g., the amount of PoE power provided by the PSE to and consumed by a PD connected to the PSE). In some examples, the fans whose speeds are controlled in this manner include at least one or more fans that provide airflow through the PSU. In some examples, only the fan(s) that provide airflow through the PSU can be controlled based on PoE power usage, while other fans (if any) that provide airflow to other parts of the PSE can be controlled based on other control schemes (e.g., based on sensed temperature). In other examples, all fans of the PSE can be controlled based at least in part on PoE power usage.

[0023] Controlling the fan speed of one or more fans based on PoE power usage as disclosed herein can allow a PSE that lacks a temperature sensor to still intelligently control its fan(s) and reduce its noise output while still providing adequate cooling. In addition, the fan control described herein can allow a PSE with a temperature sensor to further improve the cooling performance of its fans and avoid some of the difficulties described above that may arise when using only temperature-based fan control. In particular, as described above, controlling fans based solely on the sensed temperature of certain components may result in over- or under-supply of airflow to the PSU because the amount of heat generated by the PSU may be unrelated to the temperatures sensed at other components. In contrast, the amount of heat generated by the PSU depends on the amount of PoE power usage, so controlling the speed of the fan(s) that cool the PSU based at least in part on the amount of PoE power usage better reflects the thermal condition of the PSU and therefore allows the fan speed to be set closer to the optimal speed.

[0024] Many existing PSE devices are already configured to determine the amount of PoE power consumed by a PD. Furthermore, even in devices that have not yet determined this parameter, functionality for sensing this parameter can be added in a relatively cost-effective manner, often without requiring expensive redesign of the system or PSU board layout—for example, a shunt can be added to the PoE power rail to measure the current flowing therethrough, where the current is indicative of the amount of PoE power consumed. Accordingly, the examples disclosed herein can implement fan control at a lower cost than the alternative approach of providing more temperature sensors in the device.

[0025] In some examples, the measured PoE power usage can be the only parameter for controlling the fan speed of at least one or more fans that provide airflow through the PSU. For example, a fan controller can determine the fan speed of a fan by querying a fan curve based on PoE power usage, wherein the fan curve includes a function that relates PoE power usage to fan speed. The fan curve based on PoE power usage can be similar in form to the fan curve based on temperature, but temperature is not the independent variable in the curve, while PoE power usage is the independent variable. In this way, the fan speed of the (multiple) fans that supply airflow to the PSU is set directly based on the measured PoE power usage.

[0026] In some examples where fans that cool the PSU are controlled based only on PoE power usage parameters, the PSE may also include additional fans that provide airflow through other parts of the PSE, and these additional fans may be controlled based on factors other than the PoE power usage parameters. For example, a fan that causes air to flow through the processing / control circuit may be controlled based on a sensed temperature at the processing / control circuit and using a temperature-based fan curve. In other words, in these examples, a fan control scheme based on PoE power usage is used to cause air to flow through the (multiple) fans of the PSU, while a different fan control scheme (e.g., a temperature-based fan control scheme) may be used for other fans of the PSE. In this way, the different thermal requirements of various components in the PSE may be taken into account when controlling the fans that cool these components, thereby allowing each fan to be set to an optimal (or near-optimal) speed for the specific component it cools. As a result, insufficient cooling of components (particularly the PSU) and generation of unnecessary noise may be avoided or greatly reduced.

[0027] In some examples, the PoE power usage parameter is not the only parameter that controls the speed of one or more fans that flow air through the PSU, and additional parameters may also be considered. In other words, in some examples, the fan speed of one or more fans may be controlled based in part on the measured PoE power usage and in part on some other factors (such as sensed temperature). This method of using both the PoE power usage parameter and at least one other parameter to control the speed of the same fan may be referred to as hybrid fan control in this article. Hybrid fan control may be particularly suitable for (but not limited to) PSEs that have only one fan (which must cool the PSU and other components of the system at the same time) or have multiple fans that are all driven at the same fan speed, because hybrid fan control can balance the possible different cooling needs of these components by considering different parameters indicating the thermal conditions of these components (e.g., the PoE power usage of the PSU and the sensed temperature of the processing / control circuitry). Therefore, while hybrid fan control may not always cause the fans to operate at optimal speeds for all components (because there may not be an optimal speed for all components when only one fan is present or when all fans operate at the same speed), the hybrid fan control scheme can reduce the likelihood of inadequate component cooling and can reduce the amount of unnecessary noise generated compared to purely temperature-based fan control.

[0028] Turning now to the drawings, various apparatus, systems, and methods in accordance with aspects of the present disclosure will be described.

[0029] Figure 1 1 is a block diagram conceptually illustrating an example PSE 110. As will be appreciated by one of ordinary skill in the art, the PSE 110 may be, for example, a switch, a router, an access point, or any other networking device configured to supply PoE power to a connected PD. Figure 1 The specific shapes, sizes or other structural details are not intended to be accurate or to scale. Figure 1 The PSE 110 illustrated in FIG. 1 is an example, and implementations of the PSE 110 may have a different number and arrangement of the illustrated components, and may also include other parts not illustrated.

[0030] like Figure 1 As shown, the PSE 110 includes a switching hardware 120, a power supply unit (PSU) 130, and a plurality of ports 140 ( Figure 1 140 ), a control circuit 150 , and one or more fans 142 configured to provide airflow through the PSE 110 , for example to cool one or more components of the PSE 110 .

[0031] The switching hardware 120 includes switching circuitry that can selectively connect the ports 140 to each other, thereby allowing remote devices (not shown) coupled to the ports 140 to be communicatively coupled together. The switching hardware 120 can also selectively connect the ports 140 to uplink ports to allow packets to be routed between upstream devices (e.g., switches) and various remote devices connected to the ports 140 of the PSE 110. The switching hardware 120 can also have other related components that participate in, control, or otherwise facilitate the communication of packets. The switching hardware of networking devices is familiar to those of ordinary skill in the art, and therefore the switching hardware 120 is not described in further detail herein.

[0032] The power supply unit (PSU) 130 is configured to provide power to the PSE 110 to operate the functions of the PSE 110 itself, as well as to provide PoE power to the connected PD via the port 140. The PSU 130 can be controlled by the control circuit 150 to control which ports 140 receive PoE power and / or control the amount of PoE power distributed to the port 140. The PSU 130 includes one or more power supply devices that are configured to receive input power from a source such as a mains power source or a power distribution unit and convert the power into a form suitable for use by the PSE 110. The power supply devices of the PSU 130 may include an AC-DC converter, a DC-DC converter, a protection device (e.g., overcurrent protection, overvoltage protection, etc.), and / or other power components that participate in, control, or otherwise facilitate the supply of power to the PSE 110. The PSU of a networking device (e.g., a PSE) is familiar to those of ordinary skill in the art, and therefore the PSU 130 is not described in more detail herein.

[0033] The ports 140 include an RJ45 jack configured to receive a complementary RJ45 connector of an Ethernet cable to enable communication using one of the Ethernet family of protocols. Each port 140 is coupled to a control circuit 150 (e.g., via switching hardware 120) and is configured to transmit data between the control circuit 150 and a remote device (e.g., a PD) connected to the port 140. At least some of the ports 140 may include a PoE-enabled port, meaning that the port 140 is configured to not only transmit data through the PD, but also to supply PoE power to the PD via the same connector and cable. Each PoE-enabled port 140 is also coupled to a PSU 130 and is configured to supply PoE power from the PSU 130 to the PD coupled to the port 140 (unless the control circuit 150 has disabled PoE power for the port 140). Figure 1, three ports (i.e., ports 140_1, 140_2, 140_N) are shown, but any number of ports 140 equal to or greater than one may be included in PSE 110. Communication ports including PoE ports are familiar to those of ordinary skill in the art, and therefore ports 140 are not described in further detail herein.

[0034] Control circuitry 150 includes circuitry configured (e.g., programmed) to perform various operations to control PSE 110. Control circuitry 150 includes, among other things, fan control logic 151 to control one or more fans 142 by performing, among other things, operations 153 and 154. As used herein, "logic" refers to dedicated hardware, software instructions stored in a memory and coupled to a processor capable of executing the instructions, or some combination of these operations. Thus, in some examples, fan control logic 151 includes a processor (not shown) and a storage medium (e.g., Fig.13 The storage medium 160 in the fan control logic 151 stores instructions executable by the processor to cause operations 153 and 154 to be performed. In some examples, the fan control logic 151 includes dedicated hardware configured to perform operations 153 and 154, and in some examples, the fan control logic 151 includes some combination of the foregoing. The control circuit 150 may also include a processor, which may be the same processor as part of the fan control logic 151, or an additional processor, additional dedicated hardware, and / or some combination thereof to perform other operations of the control circuit 150.

[0035] In examples where the control circuit 150 and / or the fan control logic 151 include a processor, the processor may include one or more processing devices capable of executing machine-readable instructions, such as a processor, a central processing unit (CPU), a controller, a microcontroller, a system on a chip (SoC), a digital signal processor (DSP), a graphics processing unit (GPU), or other processing resources. In examples where the control circuit 150 includes dedicated hardware as an addition or alternative to the processor, the dedicated hardware may include any electronic device or logic circuit configured to perform specific operations, such as an application-specific integrated circuit (ASIC), a field-programmable gate array (FPGA), a complex programmable logic device (CPLD), a discrete logic circuit, an analog circuit, a hybrid control circuit, a hardware accelerator, a hardware encoder, etc.

[0036] In some examples, as will be further described below, the fan control logic 151 is configured to perform operation 153 to monitor the amount of PoE power used or consumed by the connected PD (or in other words, the amount of PoE power supplied by the PSU). This may include monitoring a PoE power parameter 145, also labeled herein as Pwr, which is a parameter indicating the amount of PoE power used (or another parameter from which the amount of PoE power usage can be derived). For example, in some embodiments, the PoE power parameter 145 includes an analog electrical signal indicating the amount of current flowing through a common rail that supplies PoE power to port 140 (the current indicating the amount of PoE power supplied). As another example, in some embodiments, the PoE power parameter 145 includes a digital value indicating the amount of current flowing through a common rail that supplies PoE power to port 140. In some examples, the PoE power parameter 145 is measured by the PSU and provided to the control circuit 150. In other examples, the fan control logic 151 may include circuitry for measuring the PoE power parameter 145, such as a current sensor.

[0037] The fan control logic 151 is further configured to perform an operation 154 to control the fan speed of at least one of the one or more fans 142 via the fan control signal 146 based at least in part on the amount of PoE power usage. For ease of understanding, the following description will primarily refer to a single fan 142 when describing controlling fan speed based on PoE power usage, but it should be understood that the speed of multiple fans 142 (in some cases, all fans 142) can be controlled in this manner. In addition, in some examples, the fan 142 (or multiple fans 142) whose speed is controlled based on PoE power usage includes at least the fan 142 (or multiple fans 142) that supplies airflow to the PSU 130. In some examples, additional fans 142 (or multiple fans 142) that supply airflow to other components besides the PSU 130 can have their speeds controlled based on something other than PoE power usage - for example, temperature-based fan control can be used for these other fans 142. In other examples, all fans 142 have their speeds controlled based at least in part on PoE power usage.

[0038] As part of controlling the fan speed of the fan 142 based on PoE power usage, the fan control logic 151 can determine a set point for the rotational speed of the fan 142 and generate a fan control signal 146, which instructs or otherwise causes the fan 142 to rotate according to the determined set point. The fan control signal 146 can be, for example, a pulse width modulated (PWM) signal. As is familiar to those of ordinary skill in the art, a PWM signal includes an analog electrical signal having repetitive pulses, wherein the duty cycle (pulse width) of the pulses is controlled to convey information, such as a fan speed set point in the case of the fan control signal 146. Therefore, the fan control logic 151 can determine the duty cycle of the fan control signal 146 corresponding to the desired fan speed set point, and when the fan 142 receives the fan control signal 146, the fan can set its rotational speed according to its duty cycle. Therefore, in some examples, the above-mentioned operation 154 of controlling the fan(s) 142 based at least in part on PoE power usage can include setting the fan speed set point based at least in part on the PoE power usage, and thus setting the duty cycle of the fan control signal 146.

[0039] In some examples, operation 154 includes setting the fan speed set point directly based on the PoE power usage, while in other examples, operation 154 includes setting the fan speed set point indirectly based on the PoE power usage. For example, as described in more detail below Figures 2 to 8 Some examples of fan speed set points being indirectly based on PoE power usage are shown and described in more detail below. Figures 9 to 13 Some examples where the fan speed set point is directly based on PoE power usage are illustrated. In some examples where the fan speed set point is indirectly based on PoE power usage, the fan control logic 151 can directly control the fan speed set point based on some predefined parameter (e.g., temperature) using predefined fan control schemes (e.g., temperature-based fan speed curves), and can use the fan control signal 146 to determine which of the fan control schemes to use, thereby indirectly controlling (i.e., affecting) the fan speed set point.

[0040] In some embodiments, fan control logic 151 may include a fan controller that generates fan control signal 146 and additional logic separate from the fan controller that monitors PoE power usage signal 145 and performs other control operations based on PoE power usage. In other words, in these examples, aspects of fan control related to PoE power usage may be performed by logic external to the fan controller, which may then determine a fan speed set point and generate fan speed control signal 146 based on input received from the external logic. Figure 2One such example is illustrated, as will be described in more detail below. In some other implementations, all aspects of operations 153 and 154 are integrated together into the same fan microcontroller. Fig. 9 One such example is illustrated, as will be described in more detail below.

[0041] In some examples, the fan controller that actually generates the fan control signal 146 can be formed by a commercially available fan controller that has been modified to perform operations as described herein, for example by modifying its firmware instructions. In some cases, such modifications to the firmware instructions may be relatively inexpensive to implement, especially compared to the cost of redesigning the board layout of the system board or PSU board by adding additional temperature sensors. In examples based on the PoE power usage aspects of the fan controller that utilize logic external to the fan controller to perform operations 153 and 154, relatively few modifications may be required to the fan controller's firmware instructions - for example, the firmware may be modified (if necessary) to allow the fan controller to recognize and follow instructions sent from external logic, such as instructions specifying which control scheme to use. In addition, in some cases, an already manufactured PSE is upgraded or modified to include the functionality described herein by reprogramming its fan microcontroller.

[0042] In some examples, control circuit 150 may be configured to control other operations of PSE 110 in addition to operations 153 and 154, such as controlling the operation of switching hardware 120, the operation of PSU 130, security / authentication operations, and / or other operations of PSE 110. In some examples, these functions are provided by portions of control circuit 150 other than fan control logic 151, but these other portions are not illustrated or described in detail because they are familiar to those of ordinary skill in the art.

[0043] Now go to Figures 2 to 13 , various example configurations of the fan control logic 151 will be described. Figure 2 Illustrated is fan control logic 251 , which is one example configuration of fan control logic 151 . Figures 3 to 8 Various aspects of some example configurations of fan control logic 251 and various example methods that fan control logic 251 may perform are illustrated. Fig. 9 Illustrated is fan control logic 551 , which is another example configuration of fan control logic 151 . Figures 10 to 12 Various aspects of example configurations of fan control logic 551 and example methods that fan control logic 551 may perform are illustrated.

[0044] Go to Figure 2, the fan control logic 251 will be described. In this example, the fan control logic 251 includes a control logic 261 based on power usage and a fan controller IC 262. The fan control logic 216 is configured to perform operations 253 and 255. Operation 253 corresponds to the above-mentioned operation 153 and includes monitoring PoE power usage. Operation 255 includes selecting a fan speed control scheme based on PoE power usage. The fan control scheme can be selected from one of a plurality of fan control schemes 257 stored (or accessible) in the fan controller IC 262. Figure 2 M fan control schemes 257 are illustrated, where M is any integer equal to or greater than 2. These fan control schemes 257 may include, for example, temperature-based fan curves. For example, in some embodiments, the PoE power usage signal 145 is compared to one or more thresholds, and different fan control schemes 257 (e.g., temperature-based fan curves) may be selected depending on which threshold the PoE power usage signal 145 exceeds. In some embodiments, the aggressiveness (e.g., slope) of the temperature-based fan curve may increase as the PoE power usage increases, so that when the PSU 130 is heavily loaded, more airflow is provided to it than when the PSU 130 is lightly loaded at the same sensed temperature. In some examples, one of the fan control schemes 257 may include the fan 142 being turned off or set to a fixed minimum value. In some examples, one of the fan control schemes 257 may include the fan 142 being set to a fixed maximum value. As another example, in some embodiments, the fan speed control scheme 257 may include both a temperature-based fan curve and a PoE power usage-based fan curve, and the temperature-based fan curve may be used when the PoE power usage is below a certain threshold, and the PoE power usage-based fan curve may be used if the PoE power usage is above the threshold. Various examples of the above operation 255 may include examples of hybrid fan control as described above.

[0045] Operation 255 also includes instructing fan controller IC 262 to utilize the selected fan speed control scheme via sending signal 247 to fan controller IC 262. Signal 247 may be a digital or analog signal that causes fan controller IC 262 to utilize the selected fan control scheme.

[0046] The fan controller IC 262 is configured to generate the fan control signal 146 to set the airflow provided by the one or more fans 142 based on a selected fan speed control scheme (e.g., based on one or more preloaded fan speed profiles), as understood by one of ordinary skill in the art. In some examples, the fan control logic 151 includes or is communicatively coupled to one or more temperature sensors 262 that sense a temperature within the PSE 110 and provide a signal 248 indicative of the temperature to the fan controller IC 262, wherein the fan controller IC 262 generates the fan control signal 146 based at least in part on the signal 248. For example, as described above, the fan controller IC 262 may utilize a fan speed profile that maps a sensed temperature to a fan speed set point. The temperature sensor(s) 263 may, for example, be configured to sense a temperature of one or more portions of the control circuit 150, such as a temperature of a processor thereof.

[0047] The selection of the fan control scheme in operation 255 and the generation of the fan control signal 146 by the fan controller IC 262 according to the selected fan control scheme in operation 256 together constitute the collective operation 254, which is the collective operation described above with respect to Figure 1 1. In other words, in this example implementation, operation 254 (which corresponds to operation 154) is performed in part by power usage-based control logic 261 and in part by fan controller IC 262. In some examples, fan controller IC 262 may be a commercially available fan microcontroller that utilizes a temperature-based fan curve, as is familiar to one of ordinary skill in the art, and power usage-based control logic 261 may include logic separate and distinct from fan controller IC 262, such as another microcontroller, a general purpose processor that executes instructions, or other logic circuitry.

[0048] Now go to Figure 3 , method 300 will be described. Method 300 may be performed by fan control logic 151 or 251. Method 300 includes steps corresponding to the example implementations of operations 253 and 255 described above.

[0049] At block 302 , fan control logic monitors a PoE power signal Pwr indicative of total PoE power usage.

[0050] At block 304, the fan control logic determines whether Pwr is less than a first threshold. If Pwr is less than the first threshold, the method continues to block 306. If Pwr is greater than the first threshold, the method continues to block 308. The condition of equality between Pwr and the first threshold can be arbitrarily considered a positive result or a negative result as desired by a particular implementation. Therefore, unless otherwise explicitly stated, references herein to determining whether Pwr is less than or greater than a threshold do not necessarily mean what will happen under the condition that Pwr is equal to the threshold.

[0051] In block 306, the fan control logic selects a first fan control scheme to control the fan. In some examples, the first fan control scheme includes turning the fan off (or keeping it off if already off). In other examples, the first fan control scheme includes a first temperature-based fan curve.

[0052] In block 308, the fan control logic selects a second fan control scheme to control the fan. The second fan control scheme is different from the first fan control scheme. In some examples, the second fan control scheme includes a second temperature-based fan curve. In some examples, the second fan control scheme includes a fan curve based on PoE power usage. In other examples, the second fan control scheme includes a fan curve based on temperature power usage.

[0053] Now go to Figure 4 , an example circuit 400 will be described that may be used to implement aspects of the fan control logic 251. The circuit 400 may be used, for example, to perform the method 300 described above.

[0054] Circuit 400 includes current sensor 375, which is coupled to PoE power rail 132 of PSU 130. PoE power rail 132 is the rail that supplies PoE power to port 140 and then from port 140 to any PD coupled thereto. Figure 4 In the embodiment, port 140 and the PD connected thereto are collectively referred to as load 160. Power rail 132 may be a DC power rail, and in some examples, current sensor 375 is coupled to the positive branch of power rail 132 upstream of load 160, such as Figure 4 In other examples, the current sensor 375 is coupled to the return (ground) branch of the power rail 132 downstream of the load 160 .

[0055] like Figure 4 As shown, in some examples, the current sensor 375 includes a shunt 376 that is placed in the current path of the power rail 132 so that all current flowing from the PSU 130 to the load 160 passes through the shunt 376. The shunt 376 includes a low-resistance resistor with a precisely known resistance value so that the voltage difference across its terminals (i.e., Vs+ -V s- ) is proportional to the current flowing through the shunt 736. Therefore, by reading this voltage difference, the current can be sensed. Thus, the current sensor 375 may also include a voltmeter to determine the voltage difference V s+ -V s- . In Figure 4 In one example shown, the voltmeter is a differential amplifier 377, and the terminals of the shunt 376 may be coupled to the input terminals of the differential amplifier 377 such that the differential amplifier produces an analog output signal Pwr, the voltage of which is proportional to the voltage difference across the terminals of the shunt 735, i.e., to V s+ -V s- is proportional. This is merely an example of how the current sensor may be configured, and any type of current sensor may be used as the current sensor 375. The current sensing performed by the current sensor 375 is an example of how the PoE power consumption can be monitored in accordance with operation 153 or 253 in Figure 1 or Figure 2 or according to step 302 of method 300 in Figure 3 .

[0056] The circuit 400 further includes a comparator 378_1. The comparator 378_1 receives the signal Pwr output by the current sensor 375 at one input terminal and a reference voltage Ref_1 at the other input terminal. The comparator 378_1 compares Pwr with Ref_1 and outputs a binary voltage signal Out_1 based on the comparison. For example, if Pwr is greater than Ref_1, Out_1 may have a high voltage, or if Pwr is less than Ref_1, it may have a low voltage. The comparison performed by the comparator 378_1 is an example of how to select a fan speed control scheme in accordance with operation 255 of the fan control logic 251 or in accordance with steps 304 to 308 of method 300. Specifically, the reference voltage Ref_1 is an example of the "first threshold" in block 304 of method 300, and the comparison of Pwr with Ref_1 by the comparator corresponds to the determination made in block 304. The "yes" determination result in block 304 corresponds to the comparator determining that Pwr < Ref_1, while the "no" determination result in block 304 corresponds to the comparator determining that Pwr > Ref_1.

[0057] Then the signal Out_1 can be sent to the fan controller IC 262, where the signal Out_1 corresponds to the above signal 247 indicating which fan control scheme the fan controller IC 262 uses. That is, as Figure 5As shown, a low voltage value of Out_1 may correspond to a first fan control scheme, while a high voltage value of Out_1 may correspond to a second fan control scheme. Therefore, a low voltage value of comparator 378_1 outputting Out_1 may correspond to instructing fan controller IC 262 to use the first fan control scheme as part of operation 255 of control logic 251 or block 306 of method 300, while a high voltage value of comparator 378_1 outputting Out_1 may correspond to instructing fan controller IC 262 to use the second fan control scheme as part of operation 255 of control logic 251 or block 306 of method 300. Accordingly, fan controller IC 262 may know which of these fan control schemes to use based on the current voltage of Out_1. As conditions change, Out_1 may change, and then fan controller IC 262 may change which fan control scheme to use.

[0058] The situation where Pwr is equal to Ref_1 can be handled according to whatever voltage the comparator used happens to output when this situation occurs. For example, if comparator 378_1 outputs a "low" voltage when its inputs are equal, then the condition of Pwr=Ref_1 causes the first fan control scheme to be selected, but if comparator 378_1 outputs a "high" voltage when its inputs are equal, then Pwr=Ref_1 causes the second fan control scheme to be selected.

[0059] like Figure 4 As shown, the signal Out_1 may be output to the fan controller IC 262 via an isolator / coupler 379 (eg, an optocoupler 379 ). The isolator / coupler 379 may be used to provide galvanic isolation between the power rail 132 and the fan controller IC 262 .

[0060] Now go to Figure 6 , method 300' will be described. Method 300' may be performed by fan control logic 151 or 251. Method 300' includes steps corresponding to the example implementations of operations 253 and 255 described above. Method 300' is a modification of method 300 described above, and thus method 300' includes some of the same steps as method 300.

[0061] Blocks 302, 304, and 306 have been described above in conjunction with method 300. However, method 300' differs from method 300 in that if Pwr is greater than the first threshold in block 304, method 300' proceeds to block 307 (rather than proceeding to block 308 as occurs in method 300). In block 307, Pwr is compared to a second threshold. If Pwr is less than the second threshold, method 300' proceeds to block 308, and a second fan control scheme is used. If Pwr is greater than the second threshold, method 300' proceeds to block 309, and a third fan control scheme is used. As with method 300, in the determination of blocks 304 or 307, the condition of equality between Pwr and the first threshold or the second threshold can be arbitrarily considered a positive result or a negative result as desired by a particular implementation. Therefore, unless otherwise expressly stated, references herein to determining whether Pwr is less than or greater than a threshold do not necessarily mean what will happen under the condition that Pwr is equal to the threshold.

[0062] Now go to Figure 7 , an example circuit 400' that can be used to implement various aspects of the fan control logic 251 will be described. The circuit 400' can be used, for example, to perform the above-described method 300'. The circuit 400' is a modification of the above-described circuit 400, and thus the circuit 400' includes some components that are similar or identical to the components in the circuit 400. These identical or similar components in the circuit 400' are given the same reference numerals as the reference numerals used in the circuit 400, and repeated descriptions thereof are omitted below.

[0063] Circuit 400' is similar to circuit 400, except that it includes an additional comparator 378_2. Similar to comparator 378_1, comparator 378_2 is configured to receive a signal Pwr at one of its input terminals and receive a reference voltage at another of its input terminals, and compare Pwr with the reference voltage. However, comparator 378_2 differs from comparator 378_1 in that the reference voltage (i.e., Ref_2) provided to comparator 378_2 is different from the reference voltage (i.e., Ref_1) provided to comparator 378_1. In some examples, Ref_2>Ref_1. Comparator 378_2 outputs a signal Out_2 based on the comparison of Pwr and Ref_2. For example, if Pwr is greater than Ref_2, Out_2 may have a high voltage, or if Pwr is less than Ref_2, it may have a low voltage.

[0064] The comparisons performed by comparator 378_1 and comparator 378_2 together form one example of how a fan speed control scheme may be selected in accordance with operation 255 of fan control logic 251 or in accordance with steps 304 to 309 of method 300'. Specifically, the comparison of Pwr to Ref_1 by comparator 378_1 corresponds to the determination made in box 304 of method 300', where reference voltage Ref_1 is an example of a "first threshold," and the comparison of Pwr to Ref_2 by comparator 378_2 corresponds to the determination made in box 307 of method 300', where reference voltage Ref_2 is an example of a "second threshold." In this example, signal 247 includes a combination of signals Out_1 and Out_2, and the fan control scheme indicated by signal 247 may be encoded by various combinations of voltage values ​​that Out_1 and Out_2 may take. For example, as Figure 8 As shown, in one embodiment, if both Out_1 and Out_2 are low, this indicates that a first fan control scheme is selected (e.g., it may keep the fan in an off state). This result corresponds to block 306 of method 300', which is reached when Pwr is less than a first threshold (i.e., Ref_1). Continuing with this example, if Out_1 is high and Out_2 is low, this indicates that a second fan control scheme is selected (which may be, for example, a first fan curve, in Figure 8 This result corresponds to block 308 of method 300', which is reached when Pwr is greater than a first threshold (i.e., Ref_1) but less than a second threshold (i.e., Ref_2). Finally, in this example, if both Out_1 and Out_2 are high, this indicates that a third fan control scheme is selected (which may be, for example, the second fan curve, in Figure 8 This result corresponds to block 309 of method 300', which is reached when Pwr is greater than a second threshold (ie, Ref_2).

[0065] The situation where Pwr is equal to Ref_1 or Ref_2 can be handled according to whatever voltage the comparator used happens to output when this situation occurs. For example, if comparator 378_1 outputs a "low" voltage when its inputs are equal, then the condition of Pwr=Ref_1 causes the first fan control scheme to be selected, but if comparator 378_1 outputs a "high" voltage when its inputs are equal, then Pwr=Ref_1 causes the second fan control scheme to be selected.

[0066] like Figure 7 As shown, the signal Out_2 may be output to the fan controller IC 262 via an isolator / coupler 379 ′ (eg, an optocoupler 379 ′). The isolator / coupler 379 ′ may be used to provide galvanic isolation between the power rail 132 and the fan controller IC 262 .

[0067] Method 300' may be similar to method 300 in that in both methods a fan control scheme is selected from a set of multiple fan control schemes based on a comparison of Pwr with a set of thresholds. In method 300, the set of thresholds includes one threshold (a first threshold) and the set of fan control schemes includes two fan control schemes, while in method 300', the set of thresholds includes two thresholds (a first threshold and a second threshold) and the set of fan control schemes includes three fan control schemes. In other words, method 300' includes an example modification of method 300 in which additional comparisons are performed using additional thresholds, which allows additional fan control schemes to be included in the set of fan control schemes from which to be selected. It should be understood that method 300' may be modified in a similar manner to include additional fan control schemes in the set of fan control schemes from which to be selected. Specifically, method 300' may be modified to add one or more additional determination boxes (similar to determination box 307) to the existing chain of determination boxes in the method in a manner similar to the manner in which method 300' is obtained by adding boxes 307 and 309 to method 300. Although not separately illustrated, each such modification to method 300 ′ is considered herein as one of the disclosed example methods.

[0068] In other words, in some example methods disclosed herein (of which methods 300 and 300' are just two examples), there is a chain of determination blocks similar to block 307, and in each such determination block, the signal Pwr is compared to a different threshold value. For each determination block, the result of the determination results in selecting a corresponding fan control scheme or leads to the next determination block in the chain (except for the last determination block in the chain, for which both determination results result in selecting a different fan control scheme). In other words, the examples disclosed herein include N determination blocks in a chain, wherein N threshold values ​​are compared to Pwr to select between M fan control schemes (e.g., Figure 2 , wherein M=N+1. The example methods contemplated herein may include any number N of such determination blocks, wherein N is any integer equal to or greater than 1. Thus, method 300' may be viewed as an example of the aforementioned example method with N=2 (and therefore M=3), and method 300 may be viewed as an example of the aforementioned example method with N=1 (and therefore M=2).

[0069] In a manner similar to the example methods disclosed herein that include any number N of determination boxes, the example circuits disclosed herein for performing these methods can include any number N of comparators (similar to comparators 378_1 and 378_2) to perform these determinations. In other words, in the same manner that circuit 400' is obtained by modifying circuit 400 to add comparator 378_2, additional example circuits contemplated herein can be obtained by adding additional comparators to circuit 400', where each additional comparator compares signal Pwr to a different reference voltage and outputs a corresponding output signal. Thus, for example, a third comparator 378_3 can compare Pwr to a third reference voltage Ref_3 and output a third output signal Out_3, a fourth comparator 378_4 can compare Pwr to a fourth reference voltage Ref_4 and output a fourth output signal Out_4, and so on, until an Nth comparator 378_N compares Pwr to an Nth reference voltage Ref_N and outputs an Nth output signal Out_N, where N is any integer equal to or greater than 1. In some examples, each successive reference voltage is greater than the previous reference voltage, i.e., Ref_1 < Ref_2 < … < Ref_N. Each different integer value of N corresponds to a different example circuit disclosed herein, and each of these circuits corresponds to and is configured to perform one of the example methods disclosed herein. For example, for each integer value N, N = 1 corresponds to circuit 400 that performs method 300; N = 2 corresponds to circuit 400' that performs method 300'; N = 3 corresponds to another circuit (not shown) that is a modification of circuit 400' (where a third comparator 378_3 is added) and performs another method (not shown) that adds another determination box after block 307 of method 300', and so on.

[0070] Now turning to Fig. 9 , another example fan control logic 551 will be described. As described above, fan control logic 551 is another example configuration of fan control logic 151.

[0071] The fan control logic includes a fan controller integrated circuit (IC) 561 in which PoE power usage-based fan control is integrated. In other words, the fan control logic 551 differs from the fan control logic 251 described above in that, in the fan control logic 551, the PoE power usage-based aspects of fan control operation are integrated into the same fan controller IC 561 along with other aspects of fan control. In contrast, in the fan control logic 251, the PoE power-based aspects of fan control (such as selecting a fan control scheme based on PoE power usage) are performed by logic that is not part of the fan controller IC 262, and the fan controller IC 262 instead simply performs fan control according to the selected fan control scheme in the same manner that the fan microcontroller normally performs fan control.

[0072] The fan controller IC 561 may include logic configured to perform operations 553 and 554. Operation 553 includes monitoring PoE power usage, similar to operations 153 and 253. Operation 554 includes setting a fan speed of one or more fans based at least in part on a PoE power usage parameter. In other words, in this example, the fan speed is set directly based on the PoE power usage. This is another difference between the fan control logic 551 and the fan control logic 251, because in the fan control logic 251, the speed of the fan is indirectly set in operation 254 based on the PoE power usage parameter.

[0073] In some examples, setting the fan speed directly based on PoE power usage in operation 554 may include querying a fan curve based on PoE power usage. As described above, the fan curve based on PoE power usage may be similar in form to the fan curve based on temperature, but the temperature is not the independent variable in the curve, but the PoE power usage is the independent variable. The fan curve can be represented in a variety of forms, including a table associating PoE power values ​​with fan speeds, a mathematical equation associating PoE power with fan speeds, etc. The fan curve (regardless of the format) can be used to determine the fan speed based on the measured PoE power usage by finding which fan speed the fan curve maps the measured PoE power usage level to. In this way, a fan curve based on PoE power usage is queried, and the fan speed of the (multiple) fans supplying airflow to the PSU is set directly based on the measured PoE power usage.

[0074] For example, if the fan curve based on PoE power usage is a table, operation 554 may include searching the table based on the measured PoE power usage level to find a PoE power value stored in the table that is equal to or closest to (rounded up, rounded down, or closest as needed) the measured value. The corresponding fan speed stored in the table associated with the PoE power usage level is then read and used as a fan speed set point by the fan controller IC 561. The fan controller IC 561 then generates the fan control signal 146 based on the determined set point.

[0075] Alternatively, as another example, if the fan curve based on PoE power usage is a mathematical equation, operation 554 may include evaluating the equation with the measured PoE power usage value input as the value of its independent variable. The resulting output of the equation is used by the fan controller IC 561 as a fan speed set point.

[0076] For example, Fig.12 An example fan curve based on PoE power usage is shown in a graph. Fig.12 As shown in the figure, the fan curve converts the PoE power consumption value (in Fig.12 In this example, when Pwr' is below threshold P1, the fan speed is set to zero (i.e., the fan is off), when Pwr' is above threshold P2, the fan speed is set to a maximum value (e.g., 100% PWM duty cycle), and when Pwr' is between P1 and P2, the fan speed varies linearly between zero and the maximum value (proportional to Pwr'). This is just one example for illustration, and a fan curve based on PoE power usage can take any form, similar to the way fan curves based on temperature can take various forms. Although the fan curve is in Fig.12 , but this need not be the case. For example, a fan curve may be represented as a finite set of discrete points, a step function, or any desired form.

[0077] A fan curve based on PoE power usage can be predetermined and stored in the fan controller IC 561. A fan curve based on PoE power usage can be determined experimentally. For example, a method for determining a fan curve based on PoE power usage includes running a test device at various different PoE power usage levels, changing the fan speed for each power usage level, observing the thermal conditions (e.g., temperature) of the components of interest (e.g., PSU), and noting which fan speeds produce the desired cooling and noise balance for each PoE power level. The tested power levels and the optimal fan speeds identified for each power level can then be stored in a table that forms a fan curve based on PoE power usage. As another example, a fan curve based on PoE power usage can be formed by modeling, where the power level and fan speed vary in a manner similar to that described above, except that they vary in a computer / mathematical model rather than in a physical test device. In addition, portions of the fan curve based on PoE power usage can be formed by interpolation, extrapolation, or other statistical or analytical methods - for example, certain points of the fan curve can be experimentally determined for two power levels (e.g., in the manner described above), and then additional points of the fan curve can be determined for power levels between these two power levels by interpolating based on the experimentally determined results.

[0078] Once the fan speed set point is determined, the fan controller IC 561 may generate and send a fan control signal 146 (FAN_Ctr) to one or more of the fans 142 to control their speed.

[0079] In some examples, the fan controller IC 561 can also control other fans 142 in the system based on parameters other than PoE power usage. For example, in some embodiments, the fan 142 or multiple fans 142 that cool the PSU can be controlled based on PoE power usage, while one or more other fans 142 that cool other components can be controlled by the fan controller IC 561 based on other parameters (such as sensed temperature). For example, the fan 142 that cools the processing / control circuit 150 can be controlled based on its sensed temperature. Therefore, in some examples, the fan control logic 551 includes a temperature sensor 563 to sense the temperature of these other components. In other examples, additional fan microcontrollers can be used to control some of the fans 142-for example, the fan controller IC 561 can control the fan 142 that cools the PSU based on PoE power usage, and another fan microcontroller (not shown) can use temperature-based fan control to control other fans in the system. In other examples, the fan controller IC 561 can control all fans 142 based on PoE power usage.

[0080] In the above description, the fan controller IC 561 controls the fan speed based solely on the PoE power consumption. However, in some examples, the fan controller IC 561 may also consider other parameters. For example, in some embodiments, the PoE power consumption parameter (Pwr) may be combined with another parameter (such as sensed temperature) to determine the combined parameter Pwr. combined , and the combined parameter P combined Can be used to directly control fan speed. Parameters can be combined by summing, averaging, or any other form of statistical combination. Parameters can also be normalized as part of the combination. For example, in one embodiment, P combined =a·Pwr+b·T, where Pwr is the measured PoE power, T is the temperature, and a and b are constants used to normalize these values. Then, in some examples, the combined parameter P can be queried. combined Fan Curves as Independent Variables. As another example, in some embodiments, the PoE power consumption parameter Pwr and another parameter (such as sensed temperature) can be used as separate independent variables in a multivariate (e.g., 3D) fan curve that maps different combinations of multiple parameters to fan speed.

[0081] The above examples of considering both Pwr and sensed temperature when setting fan speed (whether by combining parameters or by multivariate fan curves) can allow, for example, the fan speed to be set to a relatively high value when PoE power usage is high, when temperature is high, or when both are high. This can ensure that the PSU and the components whose temperature is sensed are always adequately cooled. In addition, in these examples, if both PoE power usage and temperature are low, the fan speed can be set to a low value. When high fan speed is not required to cool the PSU or the components whose temperature is sensed, this can ensure that unnecessary noise is reduced. These methods may be very suitable for examples where there is only a single fan or there are multiple fans but all fans are driven at the same speed, because this can balance the potential different needs of different components (such as PSU and processor) indicated by different parameters. Other examples disclosed herein that control fans separately based on separate parameters (e.g., controlling a fan that cools the PSU based on PoE power usage, and controlling a fan that cools the control circuit based on its sensed temperature) may be able to further reduce unnecessary fan noise, but may not be feasible in some systems that have only one fan or control their fans to all have the same fan speed.

[0082] Fig.10 An example method 600 is illustrated that may be performed by fan control logic 151 or 551. Method 600 includes steps corresponding to example implementations of operations 553 and 555 described above.

[0083] At block 602 , fan control logic monitors a PoE power signal Pwr indicative of total PoE power usage.

[0084] At block 604, the fan control logic determines a fan speed corresponding to the measured Pwr based on a fan curve based on PoE power usage.

[0085] At block 606 , the fan control logic generates a fan speed control signal that specifies the determined fan speed. For example, the fan speed control signal may be a PWM signal, and the duty cycle of the PWM signal may be set to reflect the fan speed identified in block 604 .

[0086] Now go to Fig.11 , an example circuit 700 that can be used to implement aspects of the fan control logic 251 or 551 will be described. The circuit 700 can be used, for example, to perform the operations 302 or 602 of the above-described method 300 or 600. The example circuit 700 is configured to monitor PoE power usage. Like the above-described circuits 400 and 400', the circuit 700 includes a shunt 776 to sense the current flowing through the rail 132. However, in the circuit 700, the voltage V s+ and V s- Instead of using a voltmeter to determine the analog voltage difference Pwr and then using N comparators to compare Pwr with N reference voltages to obtain N analog output signals Out_1 to Out_N as occurs in circuits 400 and 400', the analog-to-digital converter (ADC) 778 determines V s+ With V s- The difference between the analog voltages 400 and 400' and converts the analog voltage difference into a digital value Pwr' that is output as a digital signal 779. The digital value Pwr' includes a digital number that is proportional to the current flowing through the guide rail 132, and therefore Pwr' indicates the amount of PoE power usage in a manner similar to the way the analog signal Pwr indicates the amount of PoE power usage. Therefore, downstream processing circuits (such as a processor of the fan control logic 251 or 551) can use the digital value Pwr' instead of the analog signal Pwr in any of the above operations related to PoE power usage. In other words, each of the circuits 400, 400' and 700 monitors PoE power usage and generates a signal representing the PoE power usage for downstream processing operations, but the circuit 700 generates a digital value Pwr' representing the PoE power usage, while the circuits 400 and 400' generate analog signals Pwr representing the PoE power usage.

[0087] As described above, fan control logic 251 and fan control logic 551 differ from each other in two major respects: first, whether the functionality associated with operation 154 is integrated into a single fan controller IC (as in fan control logic 551) or divided between a fan controller IC and separate logic (as in fan control circuit 251); and second, whether fan speed is controlled directly based on PoE power usage (as in fan control logic 551) or indirectly based on PoE power usage (as in fan control logic 251). However, for convenience, these two specific combinations of features are illustrated and described as examples, but other combinations of features are also contemplated herein.

[0088] For example, in one example of fan control logic 151 (not shown), the functionality of operation 154 may be integrated into the same fan controller IC in a manner similar to fan control logic 551, but the fan controller IC may indirectly control fan speed based on PoE power usage in a manner similar to fan control logic 251. For example, the fan controller IC may be configured to determine a fan control scheme based on PoE power usage (similar to fan control logic 251) and then control fan speed based on the selected fan control scheme.

[0089] As another example, in one example of fan control logic 151 (not shown), the functionality of operation 154 may be divided between a fan controller IC and separate logic in a manner similar to fan control logic 251, but the fan controller IC may control fan speed directly based on PoE power usage in a manner similar to fan control logic 551. For example, the separate logic may be configured to determine a fan control scheme based on PoE power usage (similar to fan control logic 251), and the fan control IC may then control fan speed based on the selected fan control scheme, but one or more fan control schemes may include a fan curve based on PoE power usage that allows fan speed to be set directly based on PoE power usage.

[0090] Now go to Fig.13, an example computer program product is described. The computer program product includes a non-transitory computer-readable storage medium 160 storing instructions 1153 and 1154. These instructions 1153 and 1154 include computer instructions (e.g., software, firmware, etc.) corresponding to operations 153 and 154, respectively, which means that instructions 1153 and 1154 can be executed by a processor of fan control logic 151 to cause fan control logic 151 to perform operations 153 and 154, respectively. Therefore, instructions 1153 include instructions for monitoring PoE power usage of the PSE, and instructions 1154 include instructions for controlling the fan speed of the PSE based at least in part on PoE power usage. In some examples, fan control logic 151 includes a processor and a storage medium 160, and is configured to perform operations 153 and 154 by means of instructions 1153 and 1154 stored in storage medium 160.

[0091] In the above description, various types of electronic circuits are described. As used herein, "electronic" is intended to be broadly understood to include all types of circuits that utilize electricity, including digital and analog circuits, direct current (DC) and alternating current (AC) circuits, and circuits for converting electricity into another form of energy, as well as circuits for performing other functions using electricity. In other words, as used herein, there is no distinction between "electronic" circuits and "electrical" circuits.

[0092] It should be understood that both the general description and the detailed description provide examples that are illustrative in nature and are intended to provide an understanding of the present disclosure without limiting the scope of the present disclosure. Various mechanical, compositional, structural, electronic and operational changes may be made without departing from the scope of the present specification and claims. In some instances, well-known circuits, structures and techniques are not shown or described in detail to avoid blurring these examples. In two or more drawings, the same number represents the same or similar elements.

[0093] In addition, unless the context indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms as well. In addition, the terms "comprises", "comprising", "includes", etc. specify the presence of stated features, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, steps, operations, elements, components, and / or groups. Unless explicitly stated otherwise, components described as coupled may be directly electrically or mechanically coupled, or may be indirectly coupled via one or more intermediate components. Unless the context of the specification indicates otherwise, mathematical and geometric terms do not necessarily have to be used in accordance with their strict definitions, as one of ordinary skill in the art will understand that, for example, substantially similar elements that function in a substantially similar manner may easily fall within the scope of a descriptive term, even if the term also has a strict definition.

[0094] And / or: Occasionally, the phrase "and / or" is used herein in conjunction with a list of enumerated items. This phrase is meant to include any combination of the items in the list - from a single item to all items, and any permutations in between. Thus, for example, "A, B, and / or C" means "one of {A}, {B}, {C}, {A, B}, {A, C}, {C, B}, and {A, C, B}."

[0095] Elements and related aspects described in detail with reference to one example may be included in other examples where they are not specifically shown or described when feasible. For example, if an element is described in detail with reference to one example and is not described with reference to a second example, the element may still be claimed to be included in the second example.

[0096] In addition, unless otherwise stated herein or the context implies otherwise, when approximate terms such as "substantially," "approximately," "about," "around," "roughly," and the like are used, this should be understood to mean that mathematical precision is not required, but rather refers to a range of variation that includes but is not strictly limited to the stated value, characteristic, or relationship. In particular, in addition to any ranges (if any) explicitly recited herein, the range of variation implied by the use of such approximate terms includes at least any insignificant variations and those variations that are typical for items of the type in question due to manufacturing tolerances or other tolerances in the relevant art. In any case, unless otherwise indicated, the range of variation may at least include values ​​within ±1% of the recited value, characteristic, or relationship.

[0097] In view of the disclosure herein, further modifications and changes will be clear to those of ordinary skill in the art. For example, the apparatus and method may include additional components or steps omitted from the diagram and description for operational clarity. Accordingly, this specification is only interpreted as illustrative and is to teach those skilled in the art the general way of performing this teaching. It should be understood that the various examples shown and described herein will be considered exemplary. Elements and materials, and the arrangement of these elements and materials can be used to replace those shown and described herein, parts and processes can be reversed, and certain features of this teaching can be utilized independently, all of which will be clear to those skilled in the art after benefiting from the description herein. Without departing from the scope of this teaching and the appended claims, the elements described herein may be changed.

[0098] It is to be understood that the specific examples set forth herein are non-limiting and that modifications in structure, dimensions, materials, and methods may be made without departing from the scope of the present teachings.

[0099] Other examples from this disclosure will be apparent to those skilled in the art from consideration of the specification and practice of the invention disclosed herein. It is intended that the specification and examples be considered exemplary only, and that the following claims be given their broadest scope, including equivalents under applicable law.

Claims

1. A power supply equipment (PSE) for Power over Ethernet (PoE), comprising: a PoE port capable of connecting to a powered device (PD) via a corresponding communication link; a power supply unit (PSU) configured to supply PoE power to the PD via the PoE port and the communication link; one or more fans configured to provide airflow through the PSE, including at least a first fan configured to provide airflow to the PSU; as well as A control circuit, the control circuit comprising fan control logic, the fan control logic being configured to: monitoring a PoE power usage parameter indicative of an amount of the PoE power supplied by the PSU; and A speed of at least the first fan is controlled based at least in part on the PoE power usage parameter.

2. The PSE of claim 1, wherein: The fan control logic is configured to control the speed of the first fan based directly on the PoE power usage parameter.

3. The PSE of claim 2, wherein: The fan control logic is configured to determine a fan speed set point for the first fan based on a PoE power usage based fan curve that maps PoE power usage values ​​to fan speed values.

4. The PSE of claim 1, wherein: The fan control logic is configured to control a speed of the first fan based in part on the PoE power usage parameter and in part on a sensed temperature.

5. The PSE of claim 1, wherein: The fan control logic is configured to control a speed of the first fan indirectly based on the PoE power usage parameter.

6. The PSE of claim 5, wherein: The fan control logic is configured to select a fan control scheme from a plurality of fan control schemes based on the PoE power usage parameter, and to control a speed of the first fan based on the selected fan control scheme.

7. The PSE of claim 6, wherein: The plurality of fan control schemes includes at least one temperature-based fan curve.

8. The PSE of claim 7, wherein: The plurality of fan control schemes include at least a first fan control scheme in which a fan is turned off.

9. The PSE of claim 7, wherein: The plurality of fan control schemes include at least a first fan control scheme in which a fan is operated at a maximum speed.

10. The PSE of claim 7, wherein: The plurality of fan control schemes includes a plurality of temperature-based fan curves.

11. The PSE of claim 6, wherein: The fan control logic is configured to select the fan control scheme from the plurality of fan control schemes by comparing the PoE power usage parameter to at least one threshold.

12. The PSE according to claim 6, in, The fan control logic includes: a current sensor configured to generate a signal indicative of current flowing through a PoE rail that delivers the PoE power to the PoE port; and at least one comparator configured to compare the signal to a reference voltage, an output of the at least one comparator indicating a selected fan control scheme; and A fan controller is configured to receive the output of the at least one comparator and to control the speed of the first fan using a selected fan control scheme indicated by the output of the at least one comparator.

13. The apparatus of claim 1, wherein: The one or more fans include a second fan configured to provide airflow to the control circuit, and the fan control logic is configured to control a speed of the second fan based on a parameter other than the PoE power usage parameter.

14. The apparatus of claim 1, wherein: The one or more fans include a second fan configured to provide airflow to the control circuit, and the fan control logic is configured to control a speed of the second fan based at least in part on the PoE power usage parameter.

15. The apparatus of claim 1, wherein: The fan control logic is configured to control a speed of all of the one or more fans based at least in part on the PoE power usage parameter.

16. A method for cooling Power over Ethernet (PoE) power supply equipment (PSE), the method comprising: monitoring a PoE power usage parameter indicating an amount of PoE power supplied by a power supply unit (PSU) of the PSE to one or more powered devices (PDs) connected to the PSE; as well as A speed of at least a first fan of the PSE is set based at least in part on the PoE power usage parameter.

17. The method of claim 16, wherein: Setting the speed of the first fan based at least in part on the PoE power usage parameter includes selecting a fan control scheme from a plurality of fan control schemes based on the PoE power usage parameter and controlling the speed of the fan based on the selected fan control scheme.

18. The method of claim 17, wherein: Selecting the fan control scheme includes comparing the PoE power usage parameter to at least one threshold.

19. The method of claim 17, wherein: Setting the speed of the first fan based at least in part on the PoE power usage parameter includes determining a fan speed set point for the first fan based on a PoE power usage-based fan curve that maps PoE power usage values ​​to fan speed values.

20. A non-transitory computer-readable medium storing instructions, the instructions being executable by a processor and configured to cause the processor to perform the following operations when executed: monitoring a PoE power usage parameter indicating an amount of PoE power supplied by a power supply unit (PSU) of a PSE to one or more powered devices (PDs) connected to the PSE; and A speed of at least a first fan of the PSE is set based at least in part on the PoE power usage parameter.

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