The present application claims priority to Indian. Provisional Patent Application No. 202241006871, which was filed Feb. 9, 2022, and is hereby incorporated herein by reference in its entirety.
A switched mode power supply (SMPS) transfers power from an input power source to a load by switching one or more power transistors or other switching elements coupled through a switch node/terminal to an energy storage element (such as an inductor, an inductance of a transformer, and/or a capacitor), which is capable of coupling to the load. If the input voltage is greater than the output voltage, the converter may be referred to as a “step-down” converter/regulator or a “buck converter.” The power transistors can be included in a power converter that includes, or is capable of coupling to, the energy storage element. A SMPS can include a SMPS controller to provide one or more gate drive signals to the power transistor(s).
In some examples, a circuit includes sensing circuitry, a synchronization circuit, and a controller. The sensing circuitry is configured to provide a comparison result based on a comparison between a reference voltage and a feedback voltage. The synchronization circuit is configured to synchronize the comparison result into a clock domain to form a synchronous comparison result. The controller is configured to receive the synchronous comparison result, determine a predicted gate control signal based on the synchronous comparison result, determine a gate control signal based on the synchronous comparison result, provide the predicted gate control signal to the sensing circuitry as the feedback voltage, and provide the gate control signal for controlling a power converter.
In some examples, a system includes a load, a power converter, and control circuitry. The power converter is provided to switch power from a power source to the load. The control circuitry is configured to provide a gate control signal for controlling the power converter to switch the power from the power source to the load. The control circuitry includes sensing circuitry, a synchronization circuit, and a controller. The sensing circuitry is configured to provide a comparison result based on a comparison between a reference voltage and a feedback voltage. The synchronization circuit is configured to synchronize the comparison result into a clock domain to form a synchronous comparison result. The controller is configured to receive the synchronous comparison result, determine a predicted gate control signal based on the synchronous comparison result, determine the gate control signal based on the synchronous comparison result, provide the predicted gate control signal to the sensing circuitry as the feedback voltage, and provide the gate control signal for controlling a power converter.
In some examples, a method includes determining a predicted gate control signal, determining a comparison result based on a comparison of a reference value to a feedback signal determined based on the predicted gate control signal, determining a gate control signal based on the comparison result, and providing the gate control signal for controlling a power converter.
As described above, a buck converter receives an input voltage (VDD) having a first value and provides an output voltage (VOUT) having a second value that is less than the first value. To control a mode of operation of the power converter, a controller provides gate control signals to one or more power transistors of the power converter. The gate control signals received by a power transistor control whether the power transistor is in a conductive state (e.g., turned on) or in a non-conductive state (e.g., turned off). Each state of a power converter involves a specific combination of transistors that are in conducting states and transistors that are in non-conducting states. To change a mode of operation of the power converter, the controller modifies the sequence of switching states that it commands the transistors to assume. In at least some examples, the controller implements a state machine or other logic such that values of the gate control signals are determined based on a mode of operation of, or for, the power converter.
For a buck converter, the control signals may be pulse frequency modulation (PFM) signals that control an amount of time that a top switch (e.g., power transistor) of the power converter is conductive, thereby controlling a charge time of an inductive element of the buck converter and a value of VOUT. To determine an amount of time for the control signal to cause the top switch to be conductive, the controller may rely on information of a value of VDD, such as whether VDD is greater than or less than a threshold value, such as a reference value or reference voltage. To determine this information, supply awareness may be implemented to estimate a charge time for the buck converter. Supply awareness, as used herein, refers to consideration of a value of VDD in determining the charge time for the buck converter. The supply awareness may be implemented by a supply awareness analog-to-digital converter (SA ADC). The SA ADC converts a difference between VDD and the threshold value, which may be based on or derived from VOUT, to a digital code. In this way, the SA ADC includes knowledge of a value of VDD (e.g., as provided by a power supply) in controlling the power converter, in comparison to other approaches for controlling a power converter based on VOUT and a reference or target value without including information of the value of VDD. Some supply awareness schemes are asynchronous, such as having components operating at different frequencies resulting from unsynchronized clock signals. However, such asynchronous approaches include a risk of capturing metastable values or experiencing clock domain crossing violations, degrading performance of the buck converter.
Examples of this description include a circuit that provides for synchronous supply awareness in a power supply. The power supply includes a power converter, such as a buck power converter, sensing circuitry, and control circuitry. The sensing circuitry includes digital, analog, or a combination thereof, components suitable for detecting a value of a signal, comparing that signal to a reference, and providing a comparison result. The control circuitry includes digital, analog, or a combination thereof, components suitable for receiving the comparison result and making control decisions for the power converter at least partially based on the comparison result. Based on the control decisions, the controller provides gate control signals for controlling the power converter. In some examples, the controller is, or implements, a finite state machine (FSM) or other circuitry suitable for performing processing or decision making based on received signals.
The control circuitry also includes a synchronization circuit. The synchronization circuit may increase an amount of delay in a critical path of the power supply, such as based on a number of clock cycles that elapse in the synchronizer providing an output signal based on a change input signals. This increased delay, in combination with a time that elapses for the controller to provide the gate control signals and the sensing circuitry to provide the comparison result, may cause the gate control signals to be provided after a charge time window (e.g., late). In some examples, the synchronization circuit and the controller operate in parallel with the sensing circuitry to decrease an amount of delay in a critical path of the power supply. For example, while the sensing circuitry is determining a current comparison result (e.g., for a time t), the synchronization circuit and the controller are operating according to an immediately preceding comparison result (e.g., for a time t−1). In some examples, a masking is performed at an output of the sensing circuitry, such as via an AND logic gate, to mitigate the occurrence of glitches resulting from state transitions of the controller. In some examples, the controller has multiple states corresponding to providing of the gate control signals. Delay of the controller may be further decreased by, for example, programming an idle state of the controller to state 1 of the states rather than state 0.
In an example of operation of the system 100, the power converter 104 receives a VDD from a power source (not shown) and provides a voltage VOUT based on VDD and control exerted by the control circuitry 106. In some implementations, the power converter 104 is a buck power converter such that VOUT is less than VDD. VOUT is provided, for example, to the load 102, such as to power components (not shown) of the load 102 and/or facilitate other operation of the load 102. In an example, the control circuitry 106 controls the power converter 104 according to PFM. For example, the control circuitry 106 provides gate control signals that cause the gate driver 114 to provide gate drive signals to turn switches of the power converter 104 on or off. The gate control signals may be timed such that a switch of the power converter 104 is on (e.g., in a conductive state) for an amount of time determined based on a programmed value for VOUT. For example, for a greater value of VOUT with respect to VDD the gate control signals may cause the switch of the power converter 104 to be on for a longer period of time than for a lesser value of VOUT with respect to VDD.
To determine the amount of time for controlling the switch of the power converter 104 to be on, the sensing circuitry 108 compares a reference voltage (VREF) indicative of the programmed value for VOUT to a feedback voltage. Responsive to the feedback voltage being greater in value than the reference voltage, the control circuitry 106 (e.g., via the controller 112) provides the gate control signals such that an amount of time for the switch of the power converter 104 to be on is decreased. Responsive to the feedback voltage being greater in value than the reference voltage, the control circuitry 106 provides the gate control signals such that an amount of time for the switch of the power converter 104 to be on is increased. The feedback voltage is determined, in some examples, based on a value provided by a programmable resistor (not shown), where a resistance of that programmable resistor is controlled according to a predicted gate control signal provided by the controller 112. In an example, the synchronization circuit 110 synchronizes an output of the sensing circuitry 108 with a clock domain of the controller 112. For example, both the synchronization circuit 110 and the controller 112 may be clocked by a same clock signal (CLK) to facilitate the synchronization. Synchronizing the output of the sensing circuitry 108 with a clock domain of the controller 112, in some examples, mitigates metastability concerns associated with the output of the sensing circuitry 108. In some examples, the synchronization circuit 110 and controller 112 determine a value for controlling the power converter 104 during one time period while the sensing circuitry 108 determines an output value for an immediately subsequent, or next, time period.
In an example of operation, the controller 112 provides multiple output signals. A first of the output signals may be a gate control signal. The gate control signal may be provided to the gate driver 114 to control providing of gate drive signals by the gate driver 114 to the power converter 104. In some examples, the gate control signal is representative of a bus or other collection of individual signal lines, such as signal lines that each carry a single bit of a signal. In other examples, the gate control signal is provided via a single coupling, such as according to serial signaling. In an example, the gate control signal includes four bits of data, though in other examples any number of bits may be used. The four bits of data of the control signal are representative of a decimal value in a range of 0 to 15, inclusive, and indicate a charge time for the power converter 104. A second of the output signals may be a predicted gate control signal. The predicted gate control signal may be provided to the sensing circuitry 108 to control determination of an output signal of the sensing circuitry 108. In some examples, the predicted gate control signal is representative of a bus or other collection of individual signal lines, such as signal lines that each carry a single bit of a signal. In other examples, the predicted gate control signal is provided via a single coupling, such as according to serial signaling. In an example, the predicted gate control signal includes four bits of data, though in other examples any number of bits may be used. In at least some examples, the predicted gate control signal has a same number of bits as the gate control signal. The four bits of data of the predicted control signal are representative of a decimal value in a range of 0 to 15, inclusive, and indicate a predicted charge time for the power converter 104. In an implementation, a predicted gate control signal becomes the gate control signal in an immediately subsequent clock cycle of the system 100. A third of the output signals may be a mask. The mask may be a single bit and may be provided to the logic circuit 208 in implementations of the control circuitry 106 that include the logic circuit 208. The mask bit may have a deasserted value for two clock cycles of the control circuitry 106 and an asserted value for a next consecutive two clock cycles of the controller 112 with this pattern repeating to mitigate the occurrence of glitches resulting from state transitions of the controller 112 during the deasserted periods. For example, an output signal of the comparator 206 may include glitches, or false values within a first two clock cycles of the predicted gate control signal changing in value. Masking the output of the comparator 206 may mitigate such glitches adversely affecting operation of the controller 112.
Based on a value of the predicted gate control signal, a resistance of the resistor 202 is modified to cause, in combination with a current sunk by the current source 204, a voltage to be provided at an inverting input of the comparator 206. In some examples, the resistor 202 is implemented as a resistor ladder with a plurality of switches (not shown) that are respectively controlled according to one bit of the predicted gate control signal to program the resistance of the resistor 202. In an example, the voltage provided at the inverting input of the comparator 206 is based on VDD, as modified by the resistance of the resistor 202, controlled based on the predicted gate control signal, as described herein. A non-inverting input of the comparator 206 may be configured, via any suitable coupling, circuit architecture, or component, to receive a reference signal having a programmed value for VOUT (e.g., indicative of an intended value for VOUT). Based on a comparison of values at its non-inverting and inverting inputs, the comparator 206 provides an output signal (e.g., a comparison result) indicating whether the reference signal has a value greater than the voltage provided by the resistor 202. Responsive to the reference signal being greater in value than the voltage provided by the resistor 202, the comparator 206 provides the comparison result having a value of 1. Responsive to the voltage provided by the resistor 202 being greater in value than the reference signal, the comparator 206 provides the comparison result having a value of 0. The comparison result is provided to the logic circuit 208, in implementations in which the logic circuit 208 is included in the control circuitry 106. The logic circuit 208, in some examples, performs a logical operation between the comparison result received from the sensing circuitry 108 and the mask received from the controller 112. In some implementations, that logical operation is a logical AND. The logic circuit 208, in some examples, protects against glitches in the comparison result affecting operation of the synchronization circuit 110 or the controller 112. An output of the logic circuit 208, or the comparison result of the sensing circuitry 108 in implementations of the control circuitry 106 that omit the logic circuit 208, is provided to the synchronization circuit 110.
The synchronization circuit 110 may have any suitable architecture for performing signal synchronization. In an example, the synchronization circuit includes multiple latches 210, such as three latches 210. The latches 210 may be cascaded in series where a first of the latches 210 receives an input of the synchronization circuit 110 and its output is provided as an input of the next latch 210, continuing serially, until an output provided by a final latch 210 of the serial cascade is provided as an output of the synchronization circuit 110. Each latch 210 of the synchronization circuit 110 may be clocked by CLK, as received by the synchronization circuit 110 at a clock input of the synchronization circuit 110, which may also be received at a clock input of the controller 112 and clock the controller 112. In this way, the input signal to the synchronization circuit 110 may be synchronized into a clock domain of the controller 112. The synchronization mitigates glitches or other adverse effects in operation of the control circuitry 106 or power converter 104 resulting from metastability of an asynchronous input signal to the controller 112.
In some examples, the controller 112 implements a finite state machine or other control process. The controller 112 receives an output signal of the synchronization circuit 110 and, based on that output signal, determines a value for the gate control signal and the predicted gate control signal. Responsive to the output signal of the synchronization circuit 110 having a value of 0, the state machine may reset to a state of 0. Responsive to the output signal of the synchronization circuit 110 having a value of 1, the state machine may increment a state of operation by 1. Based on the state of the state machine, the controller 112 provides the gate control signals to the gate driver 114 to control the power converter 104, as described in greater detail below.
In an example, the power converter 104 includes a transistor 212, a transistor 214, an inductor 216, and a capacitor 218. The transistor 212 has a gate coupled to a first output of the gate driver 114, a source coupled to a power supply (not shown) to receive VDD, and a drain. The transistor 214 has a gate coupled to a second output of the gate driver 114, a source coupled to ground, and a drain coupled to the drain of the transistor 212. The inductor 216 has a first terminal coupled to the drain of the transistor 212 and a second terminal coupled to ground through the capacitor 218. In an example, an output of the power converter 104 (e.g., VOUT) is provided at the second terminal of the inductor 216 such that, in the example of
Conventionally, a state machine may begin at a state 0 as a reset, or default, state. As shown in
At operation 402, a determination is made as to whether an output of the comparator 206, indicated in
At operation 404, the controller 112 provides the gate control signal having a value of the state of operation of the state machine (in a first instance of operation 404 after proceeding directly from operation 402, a value of “1”), increments a state of operation of the state machine by 1, provides the predicted gate control signal having a value of the new state of operation of the state machine (in a first instance of operation 404 after proceeding directly from operation 402, a value of “2”), and proceeds to operation 406.
At operation 406, a determination is made as to whether an output of the comparator 206 has a value of 1. In at least some examples, the output of the comparator 206 is a next output of the comparator 206 and differs from the output of the comparator 206 considered at operation 402. Responsive to comp out having a value of 1, the method 400 returns to operation 404. Responsive to comp out not having a value of 1, the method 400 ends.
Returning to operation 402, responsive to comp out not having a value of 1, the method 400 proceeds to operation 408. At operation 408, the controller 112 provides the gate control signal having a value of the state of operation of the state machine (in a first instance of operation 408 after proceeding directly from operation 402, a value of “1”), decrements a state of operation of the state machine to zero, provides the predicted gate control signal having a value of the new state of operation of the state machine (in a first instance of operation 408 after proceeding directly from operation 402, a value of “0”) and proceeds to operation 410.
At operation 410, a determination is made as to whether an output of the comparator 206 has a value of 1. In at least some examples, the output of the comparator 206 is a next output of the comparator 206 and differs from the output of the comparator 206 considered at operation 402. Responsive to comp out having a value of 1, the method 400 proceeds to operation 412. Responsive to comp out not having a value of 1, the method 400 proceeds to operation 414.
At operation 412, the controller 112 provides the gate control signal having a value of the state of operation of the state machine, increments the state of operation of the state machine by 1, and the method 400 ends.
At operation 414, the controller 112 provides the gate control signal having a value of the state of operation of the state machine, maintains the state of operation of the state machine at zero, and the method 400 ends.
The term “couple” is used throughout the specification. The term may cover connections, communications, or signal paths that enable a functional relationship consistent with this description. For example, if device A generates a signal to control device B to perform an action, in a first example device A is coupled to device B, or in a second example device A is coupled to device B through intervening component C if intervening component C does not substantially alter the functional relationship between device A and device B such that device B is controlled by device A via the control signal generated by device A.
A device that is “configured to” perform a task or function may be configured (e.g., programmed and/or hardwired) at a time of manufacturing by a manufacturer to perform the function and/or may be configurable (or re-configurable) by a user after manufacturing to perform the function and/or other additional or alternative functions. The configuring may be through firmware and/or software programming of the device, through a construction and/or layout of hardware components and interconnections of the device, or a combination thereof.
A circuit or device that is described herein as including certain components may instead be adapted to be coupled to those components to form the described circuitry or device. For example, a structure described as including one or more semiconductor elements (such as transistors), one or more passive elements (such as resistors, capacitors, and/or inductors), and/or one or more sources (such as voltage and/or current sources) may instead include only the semiconductor elements within a single physical device (e.g., a semiconductor die and/or integrated circuit (IC) package) and may be adapted to be coupled to at least some of the passive elements and/or the sources to form the described structure either at a time of manufacture or after a time of manufacture, for example, by an end-user and/or a third-party.
While certain components may be described herein as being of a particular process technology, these components may be exchanged for components of other process technologies. Circuits described herein are reconfigurable to include the replaced components to provide functionality at least partially similar to functionality available prior to the component replacement. Components shown as resistors, unless otherwise stated, are generally representative of any one or more elements coupled in series and/or parallel to provide an amount of impedance represented by the shown resistor. For example, a resistor or capacitor shown and described herein as a single component may instead be multiple resistors or capacitors, respectively, coupled in parallel between the same nodes. For example, a resistor or capacitor shown and described herein as a single component may instead be multiple resistors or capacitors, respectively, coupled in series between the same two nodes as the single resistor or capacitor.
Uses of the phrase “ground voltage potential” in the foregoing description include a chassis ground, an Earth ground, a floating ground, a virtual ground, a digital ground, a common ground, and/or any other form of ground connection applicable to, or suitable for, the teachings of this description. Unless otherwise stated, “about,” “approximately,” or “substantially” preceding a value means +/−10 percent of the stated value. Modifications are possible in the described examples, and other examples are possible within the scope of the claims.
Number | Date | Country | Kind |
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202241006871 | Feb 2022 | IN | national |