High-reliability low-cost speed-adjustable fan driving and anomaly detection circuit

Abstract

The invention belongs to the technical field of integrated circuits, and particularly relates to a speed-adjustable fan driving and anomaly detection circuit with high reliability and low cost. Comprising a current expansion driving module for providing a voltage FCC stabilized by an LDO for a fan and performing current expansion on an output current of the LDO to drive the fan; the logic control module is connected with the current expansion driving module and is used for adjusting a control signal ADJlt; n: 0gt; the value of the voltage FCC output by the LDO is changed; the open circuit and locked-rotor detection module is connected with the logic control module and the VIN port of the LDO; and the short circuit detection module is connected with the logic control module and the output end of the LDO, outputs a signal to a state flag bit FTO, and judges whether the fan is in a normal working state, an open circuit state, a locked-rotor state or a short circuit state or not according to the waveform and the level of the state flag bit FTO. The speed-adjustable fan driving circuit is integrated, and the function of detecting various abnormal states of the fan is achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of integrated circuits, and in particular relates to a high-reliability, low-cost, speed-adjustable fan driving and abnormality detection circuit. Background Art

[0002] With the increasing integration of electronic circuits, heat dissipation has become a critical issue for power electronics. This is especially true when circuits operate at high power and voltage, generating significant heat over extended periods. Without timely heat dissipation, prolonged operation can lead to elevated device temperatures, potentially shortening device lifespan and even damaging them. Consequently, device heat dissipation issues are becoming increasingly prominent.

[0003] To effectively overcome the heat dissipation challenges of device circuits, fans are widely used in the integrated circuit field as an efficient heat dissipation method. Currently, there are various fan operating status detection technologies on the market, a typical approach being to monitor the fan motor status. For example, patent publication number CN101113992A describes a fan detection circuit that includes an overcurrent protection device, a clamping circuit, a voltage divider circuit, and an electronic switch. The overcurrent protection device's terminals are connected to the fan power supply and the first terminal of the fan interface, respectively. The clamping circuit comprises D1 and D2, and the voltage divider circuit comprises R2 and R3. The clamping circuit and voltage divider circuit are connected between the second terminal of the fan interface and ground. The control terminal of the electronic switch device, T1, is connected to the central junction of the voltage divider circuit. The circuit detects fan status by measuring the fan power supply current. The clamping voltage of the diode during forward conduction is used to determine whether the fan is in place and whether there is a short circuit or short-circuit fault. The turn-on characteristic of a bipolar transistor is utilized to convert the fan operating status into a digital value for use by the monitoring system.

[0004] However, existing fan detection is mostly implemented through discrete device designs, which occupy a large PCB board area and have high discrete device costs. At the same time, using a single fan detection method, the fan speed cannot be adjusted and multiple abnormal conditions cannot be detected. Summary of the Invention

[0005] The purpose of the present invention is to provide a highly reliable and low-cost adjustable speed fan drive and anomaly detection circuit. Compared with single fan detection or direct drive fan solutions, the present invention integrates an adjustable speed fan drive circuit and realizes the detection of multiple fan anomaly states, with the outstanding advantages of simple PCB board layout and low cost.

[0006] To solve the above technical problems, the present invention provides a high-reliability, low-cost, adjustable-speed fan drive and abnormality detection circuit, comprising:

[0007] The current expansion drive module provides the fan with a voltage FCC stabilized by an LDO and expands the output current of the LDO to drive the fan;

[0008] The logic control module is connected to the current expansion drive module and adjusts the control signal ADJ <n:0>By changing the value of the voltage FCC output by the LDO, the speed of the fan is adjusted;

[0009] an open circuit and stall detection module, connected to the logic control module and the VIN port of the LDO, sampling the fan current through a sampling resistor and converting it into a voltage V0, comparing the voltage V0 with a reference voltage Vref, and outputting a voltage signal to a level shift circuit, which then performs level shifting on the voltage signal and outputs a status flag FTO;

[0010] The short-circuit detection module is connected to the output end of the logic control module and the LDO, and outputs a signal to the status flag FTO. According to the waveform and level of the status flag FTO, it is determined whether the fan is in normal operation, open circuit, blocked or short circuit state.

[0011] Preferably, the current expansion drive module includes: a transistor Q1, a resistor R0 and an LDO; the emitter of the transistor Q1 and one end of the resistor R0 are connected to the working power supply VCC, the base of the transistor Q1 is connected to the other end of the resistor R0 and the VIN port of the LDO, and the collector of the transistor Q1 is connected to the output end of the LDO and the fan.

[0012] Preferably, a resistor R1 is further included, and the resistor R1 is connected between the base of the transistor Q1 and the other end of the resistor R0.

[0013] Preferably, it further comprises an EN port and an ADJ port, and the LDO is connected to the logic control module via the EN port and the ADJ port respectively.

[0014] Preferably, the open circuit and stall detection module includes: resistors R2 to R4, a transistor Q2, a comparator CMP and a level shift circuit; one end of the resistor R2 is connected to the VIN port of the LDO, and the other end is connected to the base of the transistor Q2; the emitter of the transistor Q2 is connected to the working power supply VCC, the collector of the transistor Q2 is connected to one end of the resistor R3 and the non-inverting input end of the comparator CMP, and the other end of the resistor R3 is grounded; the inverting input end of the comparator CMP is connected to the resistor R4 with a voltage divider function, one end of the resistor R4 with a voltage divider function is connected to the working power supply VDD, and the other end is grounded; the output end of the comparator CMP is connected to the input end of the level shift circuit, and the output end of the level shift circuit outputs the status flag FTO to the logic control module.

[0015] Preferably, the resistor R4 with the voltage dividing function is a resistor string structure.

[0016] Preferably, the short circuit detection module includes: resistors R5~R9 and transistors N1~N3; one end of the resistor R5 is connected to the working power supply VDD, and the other end is connected to one end of the resistor R6 and is connected to the logic control module as a SEN port; the other end of the resistor R6 is connected to the base of the transistor N1, the emitter of the transistor N1 is grounded, the collector of the transistor N1 is connected to one end of the resistor R9 and the collector of the transistor N2 and the base of the transistor N3, and the other end of the resistor R9 is connected to the working power supply VDD; the base of the transistor N2 is connected to the resistor R7 and one end of the resistor R8, the other end of the resistor R7 is connected to the output end of the LDO, the other end of the resistor R8 is connected to the emitters of the transistors N2~N3 and is grounded, and the collector of the transistor N3 is connected to the status flag FTO.

[0017] Preferably, the logic control module is an MCU, and the power supply terminal of the MCU is connected to the working power supply VDD.

[0018] Preferably, judging whether the fan is in normal operation, open circuit, blocked rotor or short circuit state according to the waveform and level of the state flag FTO includes:

[0019] In the initial state, the SEN port is configured to a high level through the internal pull-up mode. If the status flag FTO is a square wave with a fixed period, it is determined that the fan is in a normal working state;

[0020] If the status flag FTO is continuously at a low level, it is determined that the fan is in an open circuit state;

[0021] If the status flag FTO is continuously high, it is preliminarily judged that the fan is in a stalled or short-circuited state. At this time, the MCU will immediately pull down the SEN port level. If the status flag FTO becomes low, it is judged that the fan is in a short-circuited state, otherwise the fan is in a stalled state.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The present invention integrates an adjustable speed fan drive circuit and multiple abnormality detection circuits on a chip, replacing the existing discrete device design that wastes PCB board area, thereby achieving the detection function of multiple fan states at low cost. Moreover, the present invention realizes the function of expanding the flow of the fan with greater power by using a combination of resistors R0, R1 and a flow expansion tube Q1. The resistor R0 can also be used as a sampling resistor, so a resistor with a lower power tolerance can be used, and the optional range of resistors is wide, eliminating the need to use resistors with higher precision and higher power tolerance. In addition, by cooperating with the transistor Q2 and resistor R3 designed in the sampling detection module, the sampling method is simpler, and the detection of multiple working states of the fan can be flexibly achieved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 The present invention provides a circuit diagram of a high-reliability, low-cost, speed-adjustable fan drive and abnormality detection circuit. DETAILED DESCRIPTION

[0025] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. The advantages and features of the present invention will become more apparent from the following description. It should be noted that the drawings are greatly simplified and not to exact scale, and are only used to facilitate and clearly illustrate the embodiments of the present invention.

[0026] like Figure 1 As shown in the figure, a' is the circuit design integrated in the chip, b' is the current expansion drive module; c' is the open circuit and stall detection module, and d' is the short circuit detection module. The embodiment of the present invention specifically provides a high-reliability, low-cost adjustable speed fan drive and abnormality detection circuit, including:

[0027] The current expansion drive module provides the fan with a voltage FCC stabilized by an LDO and expands the output current of the LDO to drive the fan;

[0028] The logic control module is connected to the current expansion drive module and adjusts the control signal ADJ <n:0>By changing the value of the voltage FCC output by the LDO, the speed of the fan is adjusted;

[0029] an open circuit and stall detection module, connected to the logic control module and the VIN port of the LDO, sampling the fan current through a sampling resistor and converting it into a voltage V0, comparing the voltage V0 with a reference voltage Vref, and outputting a voltage signal to a level shift circuit, which then performs level shifting on the voltage signal and outputs a status flag FTO;

[0030] The short-circuit detection module is connected to the output end of the logic control module and the LDO, and outputs a signal to the status flag FTO. According to the waveform and level of the status flag FTO, it is determined whether the fan is in normal operation, open circuit, blocked or short circuit state.

[0031] The current expansion drive module includes a transistor Q1, a resistor R0, and an LDO. The emitter of transistor Q1 and one end of resistor R0 are connected to the operating power supply VCC, the base of transistor Q1 is connected to the other end of resistor R0 and the VIN port of the LDO, and the collector of transistor Q1 is connected to the output of the LDO and the fan. The current expansion drive module is primarily used to enhance the driving capability of the LDO when using a high-power fan. In this case, the LDO acts as a voltage clamp and simultaneously diverts the LDO power consumption to the current expansion transistor Q1, reducing the LDO power on-chip and lowering the chip temperature to protect the chip. The design of this current expansion drive module allows for a wider selection of low-power sampling resistors R0 (using a resistor with a resistance of several hundred Ω to concentrate the fan power primarily on the current expansion transistor Q1), enabling flexible fan status detection with a simple and low-cost solution. This allows for the use of a standard sampling resistor R0, achieving both a higher-power current expansion solution and the ability to simultaneously function as a fan status detection resistor, enabling low-cost detection of multiple fan states.

[0032] The system further includes a resistor R1 , which is connected between the base of the transistor Q1 and the other end of the resistor R0 .

[0033] It also includes an EN port and an ADJ port, and the LDO is connected to the logic control module through the EN port and the ADJ port respectively.

[0034] The open circuit and stall detection module includes: resistors R2 to R4, a transistor Q2, a comparator CMP and a level shift circuit; one end of the resistor R2 is connected to the VIN port of the LDO, and the other end is connected to the base of the transistor Q2; the emitter of the transistor Q2 is connected to the working power supply VCC, the collector of the transistor Q2 is connected to one end of the resistor R3 and the non-inverting input of the comparator CMP, and the other end of the resistor R3 is grounded; the inverting input of the comparator CMP is connected to the resistor R4 with a voltage divider function, one end of the resistor R4 with a voltage divider function is connected to the working power supply VDD, and the other end is grounded; the output of the comparator CMP is connected to the input of the level shift circuit, and the output of the level shift circuit outputs a status flag FTO to the logic control module.

[0035] The resistor R4 for the voltage dividing function is a resistor string structure.

[0036] The short circuit detection module includes: resistors R5~R9 and transistors N1~N3; one end of the resistor R5 is connected to the working power supply VDD, and the other end is connected to one end of the resistor R6 and is connected to the logic control module as the SEN port; the other end of the resistor R6 is connected to the base of the transistor N1, the emitter of the transistor N1 is grounded, the collector of the transistor N1 is connected to one end of the resistor R9, the collector of the transistor N2 and the base of the transistor N3, and the other end of the resistor R9 is connected to the working power supply VDD; the base of the transistor N2 is connected to the resistor R7 and one end of the resistor R8, the other end of the resistor R7 is connected to the output end of the LDO, the other end of the resistor R8 is connected to the emitters of the transistors N2~N3 and grounded, and the collector of the transistor N3 is connected to the status flag FTO. When the above short-circuit detection module is used, when the fan is short-circuited, a large current will be generated from the FCC port to the ground. At this time, the status flag FTO will remain at a high level, and the MCU will immediately pull down the SEN port level. The FCC voltage will be pulled down due to the large current during the short circuit. Through the corresponding proportion design of R7 and R8, when it is judged that the FCC drops to a certain voltage, the N2 tube is turned off and N3 is turned on to pull FTO to a low level. At this time, the MCU will determine that the fan is short-circuited.

[0037] The logic control module is an MCU, and the power supply terminal of the MCU is connected to a working power supply VDD.

[0038] It also includes the following working principles:

[0039] MCU receives the need for heat dissipation when the device is at different temperatures, and can adjust ADJ <n:0>The FCC voltage is changed to adjust the fan speed. In view of the different load conditions of fans, such as high-power fans or large losses in the chip, which lead to chip overheating, the flow expansion tube Q1 is designed to improve the driving capability and reduce the heat loss in the chip.

[0040] The fan current is sampled and converted into a voltage V0 through the sampling resistor R0, transistor Q2 and resistor R3. The voltage V0 is compared with the reference voltage Vref after the voltage is divided by the resistor R4. According to the waveform and level of the status flag FTO, it is judged whether the fan is in normal operation, open circuit, blocked or short circuit state. That is: in the initial state, the SEN port is configured to a high level through the internal pull-up mode. If the status flag FTO is a square wave with a fixed period, the fan is judged to be in normal working state; if the status flag FTO is continuously low, the fan is judged to be in open circuit state; if the status flag FTO is continuously high, the fan is preliminarily judged to be in blocked or short circuit state. At this time, the MCU will immediately pull down the SEN port level. If the status flag FTO becomes low, the fan is judged to be in short circuit state, otherwise the fan is in blocked state.

[0041] The above description is only a description of the preferred embodiments of the present invention and does not limit the scope of the present invention. Any changes and modifications made by ordinary technicians in the field of the present invention based on the above disclosure shall fall within the scope of protection of the claims.

Claims

1. A high-reliability, low-cost, adjustable-speed fan drive and abnormality detection circuit, characterized in that: include: The current expansion drive module provides the fan with a voltage FCC stabilized by an LDO and expands the output current of the LDO to drive the fan; The logic control module is connected to the expansion drive module and adjusts the control signal ADJ <n:0> By changing the value of the voltage FCC output by the LDO, the speed of the fan is adjusted; an open circuit and stall detection module, connected to the logic control module and the VIN port of the LDO, sampling the fan current through a sampling resistor and converting it into a voltage V0, comparing the voltage V0 with a reference voltage Vref, and outputting a voltage signal to a level shift circuit, which then performs level shifting on the voltage signal and outputs a status flag FTO; The short-circuit detection module is connected to the output end of the logic control module and the LDO, and outputs a signal to the status flag FTO. According to the waveform and level of the status flag FTO, it is determined whether the fan is in normal operation, open circuit, blocked or short circuit state.

2. A high-reliability, low-cost, adjustable-speed fan drive and abnormality detection circuit as claimed in claim 1, characterized in that: The current expansion drive module includes: a transistor Q1, a resistor R0 and an LDO; the emitter of the transistor Q1 and one end of the resistor R0 are connected to the working power supply VCC, the base of the transistor Q1 is connected to the other end of the resistor R0 and the VIN port of the LDO, and the collector of the transistor Q1 is connected to the output end of the LDO and the fan.

3. A high-reliability, low-cost, adjustable-speed fan drive and abnormality detection circuit as claimed in claim 2, characterized in that: The system further includes a resistor R1 , which is connected between the base of the transistor Q1 and the other end of the resistor R0 .

4. A high-reliability, low-cost, adjustable-speed fan drive and abnormality detection circuit as claimed in claim 2, characterized in that: It also includes an EN port and an ADJ port, and the LDO is connected to the logic control module through the EN port and the ADJ port respectively.

5. The high-reliability, low-cost, adjustable-speed fan driving and abnormality detection circuit according to claim 1, characterized in that: The open circuit and stall detection module includes: resistors R2 to R4, a transistor Q2, a comparator CMP and a level shift circuit; one end of the resistor R2 is connected to the VIN port of the LDO, and the other end is connected to the base of the transistor Q2; the emitter of the transistor Q2 is connected to the working power supply VCC, the collector of the transistor Q2 is connected to one end of the resistor R3 and the non-inverting input of the comparator CMP, and the other end of the resistor R3 is grounded; the inverting input of the comparator CMP is connected to the resistor R4 with a voltage divider function, one end of the resistor R4 with a voltage divider function is connected to the working power supply VDD, and the other end is grounded; the output of the comparator CMP is connected to the input of the level shift circuit, and the output of the level shift circuit outputs a status flag FTO to the logic control module.

6. A high-reliability, low-cost, adjustable-speed fan driving and abnormality detection circuit as claimed in claim 5, characterized in that: The resistor R4 for the voltage dividing function is a resistor string structure.

7. A high-reliability, low-cost, adjustable-speed fan drive and abnormality detection circuit as claimed in claim 1, characterized in that: The short circuit detection module includes: resistors R5~R9 and transistors N1~N3; one end of the resistor R5 is connected to the working power supply VDD, and the other end is connected to one end of the resistor R6 and is connected to the logic control module as the SEN port; the other end of the resistor R6 is connected to the base of the transistor N1, the emitter of the transistor N1 is grounded, the collector of the transistor N1 is connected to one end of the resistor R9, the collector of the transistor N2 and the base of the transistor N3, and the other end of the resistor R9 is connected to the working power supply VDD; the base of the transistor N2 is connected to the resistor R7 and one end of the resistor R8, the other end of the resistor R7 is connected to the output end of the LDO, the other end of the resistor R8 is connected to the emitters of the transistors N2~N3 and grounded, and the collector of the transistor N3 is connected to the status flag FTO.

8. The high-reliability, low-cost, adjustable-speed fan driving and abnormality detection circuit according to claim 1, characterized in that: The logic control module is an MCU, and the power supply terminal of the MCU is connected to a working power supply VDD.

9. A high-reliability, low-cost, speed-adjustable fan driving and abnormality detection circuit according to any one of claims 1 to 8, characterized in that: The step of determining whether the fan is in a normal operating state, an open circuit, a stalled rotor, or a short circuit state based on the waveform and level of the status flag FTO includes: In the initial state, the SEN port is configured to a high level through the internal pull-up mode. If the status flag FTO is a square wave with a fixed period, it is determined that the fan is in a normal working state; If the status flag FTO is continuously at a low level, it is determined that the fan is in an open circuit state; If the status flag FTO is continuously high, it is preliminarily judged that the fan is in a stalled or short-circuited state. At this time, the MCU will immediately pull down the SEN port level. If the status flag FTO becomes low, it is judged that the fan is in a short-circuited state, otherwise the fan is in a stalled state.

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