Multi-phase dc-dc converter with phase reduction, sub-units and methods thereof

Abstract

A local control unit operable as a master or slave device comprises: a memory, the memory indicating whether a converter subunit is enabled or disabled; and an enable; a wake-up output; a communication link input interface and a communication link output interface, the communication link input interface and the communication link output interface configured to receive and send master / slave information; and a further communication link input interface and a further communication link output interface, the further communication link input interface and the further communication link output interface configured to enable current balancing and phase staggering with other enabled converter subunits; in response to a respective local output current being above a first threshold value, sending a wake-up request to a next converter subunit; and in response to the local control unit being a slave subunit; the respective local output current being below a second threshold value, and receiving master / slave information indicating that the next enabled subunit is a master subunit, disabling itself.

Description

Technical Field

[0001] This disclosure relates to a multiphase DC-DC converter, its converter subunit, its local control unit, and its operation method. Background Technology

[0002] It is well known that the efficiency of a DC-DC power converter (also known as a DC-DC converter) can vary significantly with the output current produced, and efficiency decreases if the current is too low or too high. To improve efficiency at low power, the controller of a DC-DC converter can be arranged to operate in a low-power mode: this mode will be familiar to technicians. It is also known to combine multiple power converters into sub-units to improve efficiency. Since each converter sub-unit typically operates on a different phase, this arrangement of multiple converters is often referred to as a multiphase DC-DC converter. It is also known to disable one or more converters depending on the desired power output in order to maintain high efficiency over a wide operating output range.

[0003] An example curve of the operating efficiency of this multiphase DC-DC converter is shown in Figure 1a The diagram shows the operating efficiency, which is displayed on the y-axis or vertical axis as the output current varies as shown on the x-axis or horizontal axis. Individual curves 110, 120, ..., 150 illustrate the operating efficiency characteristics when operating 1, 2, ..., and up to 5 converter sub-units in normal power mode. By enabling or disabling individual sub-units as needed, allowing each sub-unit to provide an output current within an acceptable range of minimum and maximum values, high operating efficiency can be maintained, as shown by solid line 170.

[0004] Conventionally, such multiphase DC-DC converters are controlled by a central controller that provides control information to each of the individual converter sub-units. However, for some applications, such as when the number of sub-units is very high or when a centralized controller is not authorized for fault tolerance, distributed control may be required, and at least one method for doing so has recently been proposed. In this case, determining when and how to enable or disable individual converter sub-units without a central controller can be challenging. Summary of the Invention

[0005] According to a first aspect of the invention, a local control unit is disclosed, configured for use in a converter sub-unit of a multiphase DC-DC converter, the multiphase DC-DC converter comprising a plurality of converter sub-units arranged in parallel, each converter sub-unit having a corresponding inductor, a corresponding switching unit, and a corresponding local control unit, the local control units being arranged in a logical daisy chain, the local control unit comprising: a status indicator indicating whether the converter sub-unit is operable as a master (M) sub-unit or operable as a slave (S) sub-unit; a memory designated to indicate whether the converter sub-unit is enabled or disabled; an enable input configured to receive an enable request; a wake-up output configured to send a wake-up request; a communication link input interface; and a communication link input interface. The communication link output interface, the communication link input interface, and the communication link output interface are respectively configured to receive and transmit master / slave information; and additional communication link input interfaces and additional communication link output interfaces are configured to implement or manage current balancing and phase interleaving with other enabled converter subunits; and are adapted and configured to: in response to a corresponding local output current being higher than a first threshold, send a wake-up request to enable the next converter subunit; and in response to (a) the status indicator indicating that the local control unit is operable as a slave subunit; (b) the corresponding local output current being lower than a second threshold, and (c) receiving master / slave information indicating that the next enabled subunit in the daisy chain is a master subunit, disable itself. The enable request may typically correspond to a wake-up request sent from a previous local control unit; alternatively, the enable request may come from a start signal or a global wake-up request. Thus, each converter subunit is locally controlled by means of its corresponding local control unit. This typically includes not only current balancing between converter sub-units, but also decisions about locally enabling or disabling the converter sub-units without requiring a central controller.

[0006] The local control unit can thus determine whether it should deactivate itself in order to reduce the total number of phases of the multiphase DC-DC converter, relying solely on information provided by the local control unit from its adjacent local control units in the daisy chain.

[0007] In one or more embodiments, the local control unit is further adapted and configured to: enter a low-power control mode in response to (a) the status indicator indicating that the local control unit is operable as the master control subunit; (b) the corresponding local output current being lower than the second threshold; and (c) receiving master / slave information indicating that the next enabled subunit in the daisy chain is the master control subunit; and enter a normal control mode in response to (a) the status indicator indicating that the local control unit is operable as the master control subunit, (b) the corresponding local output current being higher than the first threshold, and (d) the local control unit being in the low-power control mode. Thus, when the local control unit is the only operating converter subunit and normal operation would result in excessively low output current and efficiency, the local control unit can be enabled to enter a low-power mode via power mode.

[0008] In one or more embodiments, the low-power control mode includes one of the following modes: a hysteresis control mode, such as pulse frequency modulation (PFM) or automatic pulse skipping (APS); or a linear regulation mode, such as low dropout output (LDO). It should be noted that these are merely examples, and those skilled in the art will be familiar with various low-power control modes facilitated according to this disclosure.

[0009] In one or more embodiments, the local control unit is further configured to connect the communication link input interface and the communication link output interface at the end of a programmable delay after the local control unit has deactivated itself, so that master / slave information can pass through. This facilitates the orderly reduction of more than one phase.

[0010] In one or more embodiments, the local control unit further includes: a global wake-up output configured to transmit a global enable request to all other converter subunits of the DC-DC converter; and a start input configured to receive the global enable request. This enables rapid startup of a multiphase DC-DC converter with full current capacity.

[0011] In one or more embodiments, the communication link interface and additional communication link interfaces are arranged to a common parallel bus or to a separate parallel bus. In other embodiments, the communication link interface and additional communication interfaces are arranged to a common serial bus. As will be understood from the detailed description below, the communication links are parallel and similar embodiments are particularly easy to implement. However, in some embodiments, it may be suitable to include digital control using serial communication links.

[0012] In one or more embodiments, the local control unit further includes an input from a comparator configured to determine whether the current output is greater than a third predetermined threshold (Iinrush), and configured to broadcast a general wake-up signal in response to a signal indicating that the output current is higher than the third predetermined threshold. This enables rapid startup of a multiphase DC-DC converter with full current capacity in the event of an inrush current event.

[0013] According to another aspect of this disclosure, a controller for a multiphase DC-DC converter is provided, the controller including a plurality of local control units as described above, the local control units being logically arranged in a daisy chain. In one or more embodiments, the plurality of local control units are identical. In such embodiments, the controller to act as the master controller can be determined at some time before the controller is operated. In other embodiments, one of the controllers is pre-configured as the master controller.

[0014] According to another aspect of this disclosure, a DC-DC converter including such a controller is provided, wherein the DC-DC converter includes a corresponding inductor and a corresponding switching unit associated with each local control unit, the corresponding inductor and the corresponding switching unit together with the local control unit forming a corresponding converter subunit.

[0015] According to another aspect of this disclosure, a method for controlling a multiphase DC-DC converter is provided. The multiphase DC-DC converter includes a plurality of converter sub-units arranged in parallel. Each converter sub-unit has a corresponding inductor, a corresponding switching unit, and a corresponding local control unit. Each converter sub-unit is configured to provide a corresponding local output current when enabled and not provide output current when disabled, and is configured to pass master / slave information from the next converter sub-unit in the daisy chain to the previous converter sub-unit when disabled. The corresponding local control units are logically daisy-chained. The method includes performing the following operations in an operating mode: designating one converter sub-unit as a master sub-unit and designating the other converter sub-units as slave sub-units; each local control unit receiving master / slave information indicating whether the next enabled converter sub-unit in the daisy chain is a master or a slave sub-unit.

[0016] In response to the corresponding local output current being higher than a first threshold, one of the local control units sends a request to enable the wake-up request of the next converter subunit; and in response to (a) the local control unit being a subordinate subunit, (b) the corresponding local output current being lower than a second threshold, and (c) the next enabled subunit in the daisy chain being a master subunit, the local control unit deactivates itself.

[0017] In one or more embodiments, the method further includes: in response to (a) one of the local control units being the master control subunit, (b) the corresponding local output current being lower than the second threshold, and (c) the next enabled subunit in the daisy chain being the master control subunit, the one of the local control units entering a low-power control mode; and

[0018] In response to (a) the local control unit being the main control subunit, (b) the corresponding local output current being higher than the first threshold, and (d) the local control unit being in the low power control mode, the local control unit enters the normal control mode.

[0019] In one or more embodiments, the method further includes operating in wake-up mode during a startup period by: at the start of the startup period, the master control subunit transmitting an enable request to all the subordinate subunits; and

[0020] The master control subunit transmits a signal indicating that it will act as a subordinate subunit during the duration of the startup period. This makes it possible to ensure that all local control units remain enabled during the startup period because none of these units can meet the deactivation requirement that "the next enabled subunit in the daisy chain is the master control subunit".

[0021] In one or more embodiments, the low-power control mode is one of pulse frequency modulation (PFM) and automatic pulse skipping (APS).

[0022] These and other aspects of the invention will be made clear and illustrated by reference to the embodiments described below. Attached Figure Description

[0023] The embodiments will be described by way of example only, with reference to the drawings, wherein:

[0024] Figure 1aPlot the operating efficiency relative to the output current of a multiphase DC-DC converter having one or more operable converter sub-units;

[0025] Figure 1b The minimum and maximum values ​​of the local output current Ii for a single (i-th) phase of a multiphase DC-DC converter with respect to the threshold minimum acceptable efficiency are shown.

[0026] Figure 2 The circuit diagram of a single-phase DC-DC converter is shown.

[0027] Figure 3 Showing the equivalent of Figure 2 However, the circuit diagram is for a multiphase DC-DC converter;

[0028] Figure 4 The pulse width modulation (PWM) control signal is shown, along with the output current of each phase of the multiphase DC-DC converter, and the total output current.

[0029] Figure 5 This shows the PWM signal, phase current, and associated modulation signal for one phase of a DC-DC converter;

[0030] Figure 6 This shows the AND operation for each phase of a multiphase DC-DC converter. Figure 5 The same representation, along with the resulting total output current;

[0031] Figure 7 A schematic diagram illustrating the configuration of five local control units for a distributed phase reduction method according to one or more embodiments is shown, each local control unit controlling a separate converter subunit for a phase;

[0032] Figure 8 A schematic diagram of a distributed phase reduction method according to other embodiments is shown;

[0033] Figure 9 A converter sub-unit for a multiphase DC-DC converter is schematically illustrated according to one or more embodiments;

[0034] Figure 10 A partial control unit according to other embodiments is schematically shown;

[0035] Figure 11 The arrangement of three converter sub-units according to one or more embodiments is shown;

[0036] and Figure 12 Show Figure 11 The converter subunit calculates the duty cycle of each phase at a local level.

[0037] It should be noted that the figures are illustrative and not necessarily drawn to scale. For clarity and convenience in the figures, the relative dimensions and proportions of the parts have been shown by enlarging or reducing their size. The same reference numerals are generally used to indicate corresponding or similar features in modified and different embodiments. Detailed Implementation

[0038] Figure 2 The circuit diagram of a single-phase DC-DC converter (or equivalently, one phase of a multi-phase DC-DC converter) is shown.

[0039] The converter configuration will be well known to those skilled in the art. Two transistors 210 and 220, also referred to as high-side transistor 210 and low-side transistor 220, connect the power supply (shown as Vin) to ground. The high-side and low-side transistors can be collectively referred to as a switching unit. An input smoothing capacitor Cin can be provided. The transistors are arranged to operate in a complementary manner, such that the half-bridge node 230 therebetween is alternately connected to the power supply voltage and connected to ground. The ratio between the on-times of the two transistors can be varied or modulated to achieve pulse width modulation (PWM) of the half-bridge node voltage. An inductor 240 is connected between the half-bridge node and the output. When the half-bridge node is connected to the power supply voltage, the current I through the inductor rises (the rate of increase depends on the inductance L), resulting in an output current Iout. A smoothing capacitor 250 with capacitance Cout can be provided for the output current as shown.

[0040] Figure 3 A similar circuit diagram for a multiphase DC-DC converter is shown, which will be familiar to those skilled in the art. Figure 3 The diagram shows three phases of an N-phase multiphase DC-DC converter. Each phase includes a high-side transistor and a low-side transistor, with a half-bridge node between them, which is connected to a common output point via corresponding inductors. The currents I1, Ii, ..., Ii through the 1st, ..., ith, and Nth converter sub-units (or phases) are... N The summation yields the output current Iout. The output is then supplied to a load 310, which may be a microprocessor μP as shown.

[0041] Figure 4 This illustrates the control mechanism for each of the three phases of a three-phase DC-DC converter. In this example, each phase operates in continuous current mode (CCM). (See reference above.) Figure 3As described, each converter subunit includes a pair of switches arranged in series and configured to operate in a complementary manner, such that the half-bridge node between the switches is alternately connected to the input voltage (Vin) and ground. Therefore, the voltage at the half-bridge node varies according to the PWM signal, as shown at 410, 420, and 430 for the three individual phases. When the half-bridge node is at the input voltage Vin, the current through the inductors of the converter subunit increases, and when the half-bridge node is grounded, the current decreases, resulting in a triangular current output from the converter subunit. The triangular shape may be generally asymmetrical. The current output from each converter subunit (or "phase") is shown at 415, 425, and 435, respectively. The total output current is shown at 440. Ripple on the output voltage can be reduced by the output capacitor Cout. To change the total output power, the mark-space ratio of the PWM signal varies according to the control mechanism.

[0042] As mentioned above, centralized control of multiphase DC-DC converters is conventional. However, one inventor of this disclosure has developed a method by which distributed control can be performed. Such a method is disclosed, for example, in International Patent Application Publication No. WO2014 / 005973, the entire contents of which are incorporated herein by reference. This method allows for distributed or local control of each converter subunit. The local control units of the converter subunit are arranged in a daisy-chain configuration. Each local control unit only needs to communicate with its two adjacent controllers (from the perspective of the daisy chain, the "next" and "previous" controllers).

[0043] This is implemented by introducing the concept of "automatic interleaving" of "triangular carrier signals." The concept shown is illustrated for... Figure 5 A single phase in, and Figure 6 Each of the three phases in the three-phase converter. For Figure 5 Each individual phase 510 and Figure 6 In the circuits 610, 620, and 630, symmetrical triangular waveforms are created as signals 512, 612, 622, and 632. This is achieved through temporary adjustments. Figure 5 The triangular carrier signal 512 and Figure 6One or more of the frequencies 612, 622, and 632 in the table are used to achieve appropriate phase interleaving. As specifically explained in M. Cousineau et al., “Triangular Carrier Self-Alignment Using a Modular Approach for Interleaved Converter Control” (Proceedings of the 14th European Conference on Power Electronics and Applications, August 30, 2011, pp. 1-10), the switching rate or carrier voltage level of each triangular carrier can be adjusted up or down, thereby increasing or decreasing the frequency of each triangular carrier depending on the interleaving between the corresponding triangular carrier signals of (only) two adjacent phases. Thus, appropriate, i.e., equally spaced interleaving can be achieved.

[0044] Alternatively, a triangular carrier signal can be used to directly generate a local PWM control signal. When the triangular carrier signal crosses a predetermined threshold 540 in the falling direction, the half-bridge node is set high (that is, the PWM signal 430 is set to "on"). The threshold level is set by a "modulation signal," which is determined by a voltage regulator using a control technique called Adaptive Voltage Positioning (AVP); conversely, when the modulation signal crosses the predetermined threshold in the rising direction, the half-bridge node is set low (that is, the PWM signal is set to "off"). The phase current, i.e., the current from this converter subunit, is shown at 540.

[0045] The predetermined threshold 540 can be changed, meaning the modulation signal can be altered. As shown at 550, if the predetermined threshold 540 increases, the fraction of time the modulation signal is below the threshold increases, and therefore the fraction of time the PWM signal is on increases, which causes a temporary increase in the output current from the phase and an increase in the average output voltage. Conversely, as shown at 560, if the predetermined threshold 540 decreases, the fraction of time the modulation signal is below the threshold decreases, and therefore the fraction of time the PWM signal is on decreases, which causes a temporary decrease in the output current from the phase and a decrease in the average output voltage.

[0046] Figure 6This illustrates distributed control applied to a three-phase DC-DC converter. Symmetrical triangular carrier signals are generated for each phase or converter sub-unit. Once a steady state is achieved, the triangular carrier signals have the same profile and shape, and are phase-shifted relative to each other, such that the signals are evenly distributed around 360°; however, during any steady-state phase or transient, the spacing and shape of the triangular carrier signals will vary with the increase or decrease of the conversion rate as mentioned above. In this particular example of a three-phase converter, once a steady state is achieved as shown, signals 612, 622, and 632 are shifted 120° relative to each other. Applying the same threshold to each phase results in (except for the 120° shift) identical PWM signals for each phase with the same mark interval ratio.

[0047] The mismatch (if present) between the output currents of each converter subunit using the same threshold level is primarily related to differences in the resistance path and the time switching of the power transistors that cause local errors or duty cycles. This can then be decentralized controlled using a feedback mechanism: the difference (if present) between the actual output current from one phase and the average of the actual output currents from two adjacent phases is used as a control parameter to adjust the threshold 540 up or down (550 or 560), thereby changing the PWM mark interval ratio of that phase and thus adjusting the output current of that phase.

[0048] As already mentioned and in Figure 1a As shown, the efficiency curve of a multiphase DC-DC converter rolls off at both high and low current levels. Therefore, if the total output current of a multiphase DC-DC converter falls below a certain value, efficiency can be improved by disabling one of the converter sub-units, allowing each of the remaining operating sub-units to output a higher current. However, such phase reduction is challenging in the case of distributed control as discussed above.

[0049] Figure 7A schematic diagram illustrates a configuration of five local control units 710, 720, ..., 750 for implementing a distributed phase reduction method according to one or more embodiments, each local control unit controlling a separate converter subunit or phase. The local control units are logically arranged in a daisy-chain configuration such that each local control unit has a "next" local control unit and a "previous" local control unit. For illustrative purposes only, the daisy chain is shown in this diagram, where each local control unit has a "next" local control unit adjacent to it in a clockwise direction and a "previous" local control unit adjacent to it in a counter-clockwise direction. The local control units may be substantially identical: in operation, one local control unit will be configured to act as a master (M) controller, and the remaining local control units will be configured to act as slave (S) controllers. Assuming that at the start of operation, the local control units know whether they are slave or master units, the configuration of which local control unit acts as the master unit can be made at the start of operation or earlier (e.g., during setup or calibration phases, during testing or certification, or during circuit design).

[0050] Each local control unit has an enable input En 711, 721, ..., 751 configured as shown, typically sensitive to rising or falling edge events, to receive enable requests. The enable request originates from the previous local control unit. It should be noted that in some cases, as will be discussed in more detail below, one or more local control units can be bypassed so that the enable request originates from or is derived from the previously enabled local control unit.

[0051] Each local control unit has communication links 719, 729, ..., 759 configured to receive and transmit master / slave information. These communication links do not need to be bidirectional. The purpose is to enable the local control unit to send information about whether it operates as a master or slave controller to its preceding neighboring device. Correspondingly, the communication links allow each local control unit to receive corresponding information from its next neighboring device. Similarly, in some cases, as will be discussed in more detail below, one or more local control units can be bypassed so that master / slave information originates from or is derived from the next enabled local control unit and is sent to the preceding enabled local control unit. Furthermore, it should be noted that although the information is described as master / slave information according to one or more embodiments, the local control unit does not always send information that correctly identifies its configuration. Specifically, in one or more embodiments, there are situations where the master controller may transmit information indicating that it is a slave device or at least masquerades as a slave device to the preceding device of the local control unit.

[0052] Each local control unit has a wake-up output Nwu 712, 722, ..., 752 configured to send a wake-up request to the next adjacent device of the local control unit. As will be discussed in more detail below, this output is used in operation to wake up the next local control unit, that is, to change the local control unit from a disabled state to an enabled state. Therefore, the wake-up output is connected to the enable input of the next adjacent local control unit.

[0053] Each local control unit has additional communication links 714, 724, ..., 754, configured to facilitate distributed current balancing and distributed phase interleaving of the PWM control signal with other enabled converter subunits, as discussed above; these communication links are bidirectional and allow the local control unit to communicate with its "next" and "previous" local control units. The communication link can be a four-wire parallel bus as shown; alternative configurations, such as a serial bus, will be apparent to those skilled in the art and are within the scope of this disclosure. Specifically, the communication link can be a multi-wire parallel link, or rely on serial communication using fewer lines, or even just a single line.

[0054] Each local control unit has a status indicator (not shown) designated to indicate whether the converter subunit is operable as a master (M) subunit or a slave (S) subunit. The status indicator may be stored in memory, or the information may be available in other ways. For example, the status of the control unit, "master" or "slave," may be designated by a term M. aster The input bit is state-defined (0 = slave, 1 = master). This input bit can be connected, for example, to a microcontroller unit and can be reconfigured in case of master failure, or to an internal one-time programmable (OTP) fuse or non-volatile internal memory and is therefore not reconfigurable.

[0055] Each local control unit also has a memory designated to indicate whether the converter subunit is enabled or disabled. The term "memory" will be explained in general terms herein, and the memory includes, for example, the state of a D-latch device, as will be referenced below. Figure 9 The discussion.

[0056] The present disclosure describes the control of multiphase DC-DC converters by means of local control units 710, 720, ..., 750 according to embodiments of the present disclosure, each of which can control its own converter subunit, and no central controller is required.

[0057] In summary, each local control unit can deactivate itself under certain circumstances when the local output current flowing through the inductor of its converter subunit is below a predetermined minimum value Imin. Furthermore, each local control unit can attempt to wake up its next adjacent device under certain circumstances when the local output current is above a predetermined maximum value Imax.

[0058] The inventors are aware of the "certain situations" mentioned above, which require control instructions to provide effective control and avoid confusion or conflict, as described below.

[0059] Figure 1b This shows the minimum and maximum output current for a single phase of a multiphase DC-DC converter, with respect to the local output current Ii190 for minimum threshold efficiency. Similar curves apply to each phase. Figure 1b As shown, for each phase, there is a minimum current Imin and a maximum current Imax. When the current is below the minimum current Imin, the efficiency ρ is below the threshold ρth. When the current is above the maximum current Imax, the efficiency ρ is also below the threshold ρth.

[0060] First, consider the case where each phase generates an output current less than Imin. In this case, it is necessary to deactivate one phase so that the total output current is supplied from the least number of phases, thereby allowing each operating phase to provide a higher output current Ii. However, it is necessary to prevent all phases from deactivating themselves simultaneously. According to embodiments of this disclosure, this is achieved by naming one phase as the master control device (M) and utilizing the position of the master control device in the daisy chain to ensure orderly phase deactivation.

[0061] It should be noted that the master controller is not a central controller, as each phase possesses its own autonomy. Therefore, while the master controller can be determined during manufacturing, it is equally possible to determine it only during the configuration or setup phase, or only before the operating period of the multiphase converter, provided that at the start of any operating period, one and only one of the local control units can be identified as the master controller M, and the remaining local control units can be identified as slave units S. It should also be noted that direct communication between the master controller and each of the slave units is not required for phase reduction. Specifically, as described above, the communication link is daisy-chained. Therefore, for applications where the master controller is determined only after circuit design, the design of each and all of the local control units can be identical.

[0062] As already mentioned, each local control unit can deactivate itself when the output current Ii is below a predetermined minimum value Imin, but only under certain circumstances. Specifically, a local control unit can only deactivate itself if the "next" local control unit is the master controller: recall that each local control unit has communication links 719, 729, ..., 759 configured to receive master / slave information. Specifically, the communication links allow each local control unit to receive the information from its next adjacent device. Since there is only one master controller, only the next adjacent device of one local control unit is the master device, and therefore only one local control unit can deactivate itself at any time.

[0063] Without adjusting this rule, once a local control unit preceding the master controller (as defined by its position in the daisy chain) is disabled, there are no other local control units that satisfy the condition that the next adjacent device is the master: therefore, if the current of each operating phase is still below or subsequently below 1min, other local control units will not be able to disable themselves. To avoid this, local control units are arranged to allow master / slave information to pass through when disabled. That is, when disabled, a local control unit does not transmit whether it is the master or slave to the preceding adjacent device: rather, the local control unit allows information from the next local control unit to pass through as if it were the next local control unit. Thus, the preceding local control unit receives information from the next enabled local control unit, "skipping" any disabled local control units in between.

[0064] In one or more embodiments, a programmable delay is provided between the local control unit deactivating itself and allowing master / slave information to pass through, such that the preceding adjacent device of the local control unit receives master / slave information from the next adjacent device of the local control unit. During the delay period, the deactivated local control unit may continue to transmit its own master / slave status, and since only slave local control units can deactivate themselves, those skilled in the art will recognize that the master / slave status will be 'slave' information.

[0065] It should be noted that no programmable delay is implemented for the communication links that transmit information about the local output current of adjacent converter subunits and the signals required for the necessary interleaving. Once a local control unit is deactivated, the next adjacent device and the previous adjacent device of that local control unit need to be able to communicate with each other; therefore, for this link, passthrough communication is established immediately.

[0066] As discussed, according to various embodiments of this disclosure, the local control unit can be selectively disabled or enabled depending on whether the local output current Ii is greater than a first threshold or less than a second threshold. The local output current Ii can be measured instantaneously or as an average value over a time interval. The time interval can be one or an integer number of switching cycles, or it can be a short period of time. The method for determining Ii can depend on the current sensing method. Several alternatives will be familiar to those skilled in the art, which will be referenced below. Figure 9 The alternative is briefly discussed with current sensor 962. Therefore, Ii can correspond to the instantaneous value Ii_inst, or the average or integral value Ii_int.

[0067] As a concrete example, consider Figure 7 If the local control unit 750 determines that its output current Ii is below the minimum value Imin, then the local control unit 750 will deactivate itself (because it has received information from the next adjacent device that the next adjacent device is the master device 710. Those skilled in the art will understand that this information can be transmitted in any of several ways, including continuous high / low levels on the line, or continuously or periodically transmitted digital signals, etc.). Conversely, if the local control unit 710 determines that its output current Ii is below the minimum value Imin, then the local control unit 710 cannot deactivate itself, because the local control unit 710 has received information from the next adjacent device that the next adjacent device 720 is a subordinate device. Additionally, after the local control unit 750 deactivates itself, and after any programmed delay, if the local control unit 740 determines that its output current Ii is below the minimum value Imin, then it will deactivate itself: since the local control unit 750 is deactivated, the local control unit 750 allows master / slave information to pass through, so that the local control unit 740 receives information from the next enabled adjacent device that the next adjacent device is the master device 710.

[0068] There is an additional adjustment to the rules: It is not permissible for a local control unit operating as the master controller to disable itself. Without this adjustment, the following scenario could occur: under low power requirements, all local control units would be sequentially disabled, and consequently, the multiphase converter would not provide any power at all.

[0069] According to one or more embodiments of this disclosure, if the master controller is the only local control unit that has not been disabled and the current remains below a threshold current, then the master controller may enter a low-power mode. Low-power modes will be known to those skilled in the art; generally, but not exclusively, hysteresis control will be implemented, and the hysteresis control may include pulse skip mode or pulse frequency modulation (PFM) operation. Alternatively, low-power control may be implemented through linear regulation, for example, using a low-dropout (LDO) circuit.

[0070] Now we turn to the following scenario: one or more local control units in the local control unit are deactivated, and the current supplied by the remaining enabled converter subunits with enabled local control units exceeds a predetermined maximum current Imax. As briefly mentioned, each local control unit may, under certain circumstances, attempt to wake up the next adjacent device of that local control unit. These “certain circumstances” will now be described, where control commands are required to provide effective control and avoid confusion or conflict.

[0071] In summary, the general rule is that if the current Ii from the activated phase is higher than the predetermined maximum current Imax, then a wake-up signal Nwu will be required to activate the next adjacent phase. Generally, the average value Ii_int of the local output current over one or more conversion cycles will be used, but a shorter sampling period or instantaneous value Ii_inst of the local current may also be used. Of course, the next adjacent local control unit may already be activated, in which case the wake-up signal will have no effect. However, if the next adjacent local control unit is currently deactivated, it will be activated.

[0072] Furthermore, the infrastructure described above can be used to implement other functions of multiphase DC-DC converters. First, consider the startup requirements. In a startup scenario, it may be preferable that the phase reduction function described above is not operational: specifically, a multiphase DC-DC converter may be suitable for startup with most or substantially all of its phases activated, since the actual current requirements are typically not known in advance, and therefore may be suitable for cyclically or simultaneously activating each phase, especially where the duration of the programmable delay between activating individual phases is significant.

[0073] In such embodiments, when the multiphase DC-DC converter needs to be started, that is, when current is first required after even a period of time when the main controller has been disabled, an activation signal “start” 716 is provided to the enable pin 711 of the main controller. Since the enable pin can also be set by the next wake-up Nwu of the previous local control unit, this can be implemented by including an OR logic gate as shown at 715.

[0074] As mentioned, it is probably preferable for all converter subunits to start operating simultaneously. This can be implemented by broadcasting a global wake-up signal (Gwu) to all local control units operating as slave devices.

[0075] Figure 8 This illustrates one possible implementation of this scenario. Figure 8 Similar to Figure 7In addition to the load (in this case, the microprocessor) transmitting the wake-up signal 814 to the master controller, the master controller can then broadcast a global wake-up signal to the enable pin of each slave device. Similarly, since the enable pin can receive multiple signals, this can be implemented using OR gates 825, 835, ..., 855 as shown. It should be understood that because the master controller already has an OR gate for the enable pin, all local control units (whether operable as a master or slave device) have the same layout. Figure 8 An optional start input 716 is also shown, which can be provided to the enable input EN of a local control unit operable as a master controller 710, as shown in the relevant section. Figure 7 As discussed above. However, in this embodiment, as shown, the next wake-up signal from the logically preceding controller subunit 750 remains unconnected because the master device will be substantially always operational except before the unit has been started, so the master controller 710 does not need a "next wake-up signal Nwu".

[0076] It should be understood that, for example, "start" can be a signal provided from an external component (such as the motherboard's FPGA) to start the multiphase converter and power a load such as a microprocessor. Conversely, in this case, "wake-up" is a signal provided during operation (e.g., via a load) to inform the multiphase converter that a strong, predictable load current will soon be required.

[0077] It should be understood that, alternatively, the wake-up signal can be supplied externally, for example, directly from the load to all local control units simultaneously.

[0078] Furthermore, according to embodiments of this disclosure, phase shaving can be effectively disabled by adjusting the master / slave information transmitted by the master controller during a global wake-up or startup period. During this period, the master controller can be configured to transmit information on the communication link that the master controller is a "slave device" or at least masquerades as a "slave device." As a result, the slave controller will not receive information that its next enabled neighboring device is the master device, and therefore, the slave controller cannot choose to disable itself. Of course, once the startup phase is complete, for example after a programmable delay, the master device can revert to transmitting its correct "master device" state, which facilitates subsequent phase shaving.

[0079] Figure 9A converter sub-unit 900, serving as the i-th sub-unit in a multiphase DC-DC converter according to one or more embodiments, is schematically shown. A switching unit, including a high-side transistor 230 and a low-side transistor 220, connects the power supply Vin to ground. The transistors are driven by corresponding drivers 232 and 222 and are arranged to operate in a complementary manner via control logic 905, as shown, which is included in a local control unit 910. The local output current Ii through the inductor 240 is sensed by means of a current sensor 962. Those skilled in the art will appreciate that several alternative methods of current sensing can be used.

[0080] The local control unit also includes a carrier generator 930 and a current balancing unit 940, as well as a phase reduction controller 950. An enable input to the phase reduction controller 950 is provided via a trigger 960 to remember the state (active or passive) of the entire converter subunit after a temporary wake-up or start signal.

[0081] Current balancing can be achieved, for example, as described in WO2014 / 005973. In this document, the current balancing unit 940 is connected via a separate communication link to the response current balancing units in the (i+1)th and (i-1)th converter subunits (that is, the next and previous adjacent subunits), and exchanges current information I with the (i+1)th converter subunit. i and I i+1 And exchange current information I with the (i-1)th converter subunit. i-1 and I i In order to achieve current balance.

[0082] Similarly, as described in WO2014 / 005973, the carrier generation unit 930 is connected via a separate communication link to the response carrier generation units in the (i+1)th and (i-1)th converter subunits (that is, the next and previous adjacent subunits), and exchanges triangular carrier voltage information V with the (i+1)th converter subunit. c_i and V c_i+1 And exchange triangular carrier voltage information V with the (i-1)th converter subunit. c_i-1 and V c_i This is to enable PWM control signal interleaving, as referenced above. Figure 6 The discussion. It should be noted that, although... Figure 9 These signals are shown as analog signals (e.g., reference voltage), but in alternatives, information can be exchanged digitally.

[0083] The local control unit 910 includes the following inputs and outputs for implementing the embodiments described above:

[0084] ○ Master control device: Input pin used to define whether the circuit is a master control device (M) or a slave device (S).

[0085] ○Gwu: Output pin used for global wake-up function, for use by the main control device only.

[0086] ○Nwu: Output pin used for the next wake-up, used in phase reduction order when Ii>Imax.

[0087] ○ Startup: External startup sequence input pin, for use by the main control device only.

[0088] ○ Wake-up: Input pin for external wake-up sequence, for use by the main control device only.

[0089] ○Pwu: Input pin used for the previous wake-up, required only by slave devices.

[0090] ○En: Internal signal indicating the phase's activation status.

[0091] ○Ti: Output pin for the local phase status sent to the next phase: M if it is the master, S if it is the active slave, otherwise Ti+1.

[0092] ○Ti+1: Input pin used to read the state of the next phase.

[0093] It should be understood that, since each local control unit knows whether it is operable as a master or a slave, the output pin Ti 951 indicates the state of the internal memory (which may be implemented as a flag, a bit in a numeric word, or otherwise), unless the local control unit is a master but operates in startup mode and therefore transmits “error” slave information as described above, or the local control unit is disabled. In this case, pin Ti provides a copy of the information input pin Ti+1 952 from the next adjacent local control unit.

[0094] Figure 10 A partial control unit 1000 according to one or more embodiments is schematically shown. The control unit may have other functions, such as the current balancing unit 940 described above; however, Figure 10 Only components and signals that may aid in understanding this disclosure are shown. The local control unit includes a phase-down controller 950, which is configured to enable or disable control logic 905. Figure 10 (Not shown in the diagram) to enable or disable PWM control of the local switching unit. When PWM control is disabled, both transistors are disconnected, and the half-bridge node between them is in a high-impedance state.

[0095] As discussed above, an enable input to the phase reduction controller 950 is provided via trigger 960 to remember temporary wake-up or start signals. The illustrated local control unit 1000 has two inputs to a "set" input of a D-type latch, which are combined via an OR gate: one input, Pwu 1012, is the previous wake-up input. All local control units have this input. As shown, the other input 1014 can be a "start" input, which the local control unit will have if it is configured to operate as a master controller. Alternatively, the other input 1014 can be a general wake-up input Gwu, which the local control unit will have if it is configured to operate as a slave controller.

[0096] The phase reduction controller 950 has two outputs, Nwu 1016 and Gwu 1018. The next wake-up output Nwu 1016 is daisy-chained to the Pwu input of the preceding adjacent device. The universal wake-up Gwu output is connected only when the local control unit is arranged as the master controller, in which case the output is connected to a bus that is connected to the corresponding universal wake-up input of all slave controllers.

[0097] The diagram also illustrates a "master" input. This "master" input is applied externally to a multiphase DC-DC converter, with the multiphase DC-DC converter acting as the master controller for local control units. Therefore (in a non-limiting case of non-inverting logic), this will be high for the master controller and low for all slave controllers. Those skilled in the art will recognize that this can be a transient signal or a permanent state. Furthermore, those skilled in the art will also recognize that in one or more embodiments, specifically if the master controller is established during the chip layout or manufacturing stage, this input is not required.

[0098] Already referenced Figure 9 The master-slave communication link, as well as the input and output pins Ti 951 and Ti+1952, are described, and therefore need not be repeated here.

[0099] Figure 11 The diagram illustrates an arrangement of three converter subunits according to one or more embodiments. Each converter subunit has local control units 900, 901, and 902, including a phase-cutting controller 950, as described above. The converter subunits are arranged as part of a daisy chain. As shown, the middle subunit of the three subunits is arranged as the master controller, while the other two subunits are arranged as slave controllers. Therefore, the status indicator input to the phase-cutting controller of the master controller is represented by "1", as shown, while the status indicator inputs to the other two controllers are "0", as shown.

[0100] The diagram illustrates daisy-chain communication of carrier generator information (shown at 1120) and current balance information (shown at 1110). The diagram also shows a bus comprising a shared line with an output voltage Vout, a reference voltage Vref, and a modulation voltage Vmod. The output and reference voltages are for use only by the master controller; the modulation voltage value is determined by the master controller and supplied to the bus, which is used by each of the slave controllers.

[0101] Figure 12 Show Figure 11 The converter subunit is a unit in which all phases are identical. The converter subunit is similar to... Figure 11 The converter sub-units are in the same module, but the local duty cycle is calculated in each individual sub-module, and the arrangement is similar, except for the different connections, which are highlighted by ellipse 1210. A common signal Vmod is no longer needed.

[0102] In addition to these connections, according to one or more embodiments of this disclosure, additional shared lines in the bus are provided for general wake-up. This signal is provided by the master controller as discussed above for startup or general wake-up requests: the signal serves as an input to each of the slave controllers. Furthermore, an external wake-up signal connection 814 (Ewu) may be provided only to the master controller, as shown.

[0103] Furthermore, according to one or more embodiments of this disclosure, there is a daisy-chained communication link 1130 as shown, in which each link in the daisy chain sends the next wake-up Nwu output from one local control unit and sends the previous wake-up Pwu input to the previous local control unit. Additionally, according to one or more embodiments, there is another daisy-chained communication link 1140 as shown for transmitting master / slave information.

[0104] In one or more other embodiments, a method for locally responding to inrush current is also provided: Reference Figure 1b At a local current value Iinrush higher than Imax, the local control unit can broadcast a global wake-up signal Gwu. This will subsequently override the sequential reactivation of the phases one by one, and immediately activate all phases of the multiphase DC-DC converter, thus enabling increased current output to meet inrush demands. However, as already discussed, generally, the local current output (from each converter) can be an instantaneous current value, an average value, or an integral value, but non-exclusively, the instantaneous value is used for comparison with the third threshold Iinrush. As will be understood, in cases of high inrush current, it is typically necessary to utilize all available local control units and converter sub-units.

[0105] By reading this disclosure, those skilled in the art will understand other changes and modifications. Such changes and modifications may involve equivalent and other features known in the field of multiphase DC-DC converters and may be used to replace or supplement the features already described herein.

[0106] Furthermore, while the above discussion has focused on controlling the number of active phases depending on the level of the output current, those skilled in the art will understand that this disclosure is not limited to constant voltage control, but extends to multiphase DC-DC converters operating in other types of regulation modes.

[0107] Although the appended claims are directed to specific combinations of features, it should be understood that the scope of the disclosure of this invention also includes any novel feature or combination of novel features or any generalization of such novel features as expressly or implicitly disclosed herein, regardless of whether such novel feature relates to the same invention as currently claimed in any of the claims or whether such novel feature alleviates any or all of the same technical problems as those alleviated by this invention.

[0108] Features described in the context of a single embodiment may also be provided in combination in a single embodiment. Conversely, for the sake of brevity, the various features described in a single embodiment may also be provided individually or in any suitable sub-combination. The applicant hereby reminds that new claims may be made for such features and / or combinations of such features during the examination of this application or any other application derived therefrom.

[0109] It should be noted that, as used herein, the terms “next” and “previous”, particularly when used in connection with or in combination with the term “adjacent”, refer to a position in the daisy chain of a communication link, rather than any temporal or time-based order.

[0110] For completeness, the term "comprising" does not exclude other elements or steps, the term "a (a or an)" does not exclude that a plurality of, a single processor or other unit may perform the functions of the several components described in the claims, and the reference numerals in the claims should not be construed as limiting the scope of the claims.

Claims

1. A local control unit, characterized in that, The local control unit is configured for use in a converter subunit of a multiphase DC-DC converter, the multiphase DC-DC converter comprising a plurality of converter subunits arranged in parallel, each converter subunit having a respective inductor, a respective switching unit, and a respective local control unit, the local control units being arranged in a logical daisy chain, the local control unit comprising: a status indicator indicating whether the converter subunit is operable as a master (M) subunit or as a slave (S) subunit; a second indicator indicating whether the converter subunit is enabled or disabled; an enable input configured to receive an enable request; a wake-up output configured to send a wake-up request; a communication link input interface and a communication link output interface configured to receive and send master / slave information, respectively; and a further communication link input interface and a further communication link output interface configured to enable current balancing and phase interleaving with other enabled converter subunits; and is adapted and configured to: in response to a respective local output current being above a first threshold, send a wake-up request requesting enabling of a next converter subunit; and in response to (a) the status indicator indicating that the local control unit is operable as a slave subunit, (b) the respective local output current being below a second threshold, and (c) receiving master / slave information indicating that a next enabled subunit in the daisy chain is a master subunit, disable itself.

2. The local control unit according to claim 1, characterized in that The local control unit is additionally adapted and configured to: in response to (a) the status indicator indicating that the local control unit is operable as a master subunit, (b) the respective local output current being below the second threshold, and (c) receiving master / slave information indicating that the next enabled subunit in the daisy chain is the master subunit, enter a low-power control mode; and in response to (a) the status indicator indicating that the local control unit is operable as the master subunit, (b) the respective local output current being above the first threshold, and (d) the local control unit being in the low-power control mode, enter a normal control mode.

3. The local control unit according to claim 1 or 2, characterized in that is additionally configured to connect the communication link input interface and the communication link output interface at the end of a programmable delay after the local control unit has disabled itself to pass master / slave information through.

4. The local control unit according to claim 1 or 2, characterized in that further comprises: a global wake-up output configured to transmit a global enable request to all other converter subunits in the DC-DC converter; and a start input configured to receive a global enable request.

5. The local control unit according to claim 1 or 2, characterized in that The communication link interfaces and the further communication link interfaces are arranged as interfaces to a common parallel bus or to separate parallel buses or to a common serial bus.

6. The local control unit according to claim 1 or 2, characterized in that Further comprising an input from a comparator configured to determine whether the current output is greater than a third predetermined threshold (Iinrush) and configured to broadcast a general wake-up signal in response to a signal indicating that the output current is above the third predetermined threshold.

7. The local control unit of claim 2, wherein, The low power control mode comprises one of: a hysteretic control mode comprising pulse frequency modulation (PFM) and automatic pulse skipping (APS); and a linear regulation mode comprising low drop-out output (LDO).

8. A controller for a multiphase DC-DC converter, characterized by Comprising a plurality of local control units according to any of the preceding claims, logically arranged in a daisy chain.

9. A DC-DC converter, characterized by Comprising the controller of claim 8, the DC-DC converter further comprising a respective inductor and a respective switching cell associated with each local control unit, the respective inductor and the respective switching cell forming a respective converter sub-cell together with the local control unit.

10. A method of controlling a multiphase DC-DC converter, characterized by, The multiphase DC-DC converter comprises a plurality of converter sub-cells in parallel, each converter sub-cell having a respective inductor, a respective switching cell and a respective local control unit, the respective local control units logically arranged in a daisy chain, each converter sub-cell configured to provide a respective local output current when enabled and no output current when disabled, and configured to pass master / slave information from a next local control unit to a previous local control unit in the daisy chain when disabled, the method comprising, in an operating mode: designating one local control unit as a master sub-cell and the other local control units as slave sub-cells; each of the local control units receiving master / slave information indicating whether a next enabled local control unit in the daisy chain is a master sub-cell or a slave sub-cell; in response to the respective local output current being above a first threshold, one of the local control units sending a wake-up request requesting enabling the next local control unit; and in response to (a) the one of the local control units being a slave sub-cell, (b) the respective local output current being below a second threshold, and (c) the next enabled local control unit in the daisy chain being a master sub-cell, the one of the local control units disabling itself. Further comprising an input from a comparator configured to determine whether the current output is greater than a third predetermined threshold (Iinrush) and configured to broadcast a general wake-up signal in response to a signal indicating that the output current is above the third predetermined threshold.

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