CN111987907A - Switch mode power supply circuit - Google Patents

Switch mode power supply circuit Download PDF

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Publication number
CN111987907A
CN111987907A CN202010446658.0A CN202010446658A CN111987907A CN 111987907 A CN111987907 A CN 111987907A CN 202010446658 A CN202010446658 A CN 202010446658A CN 111987907 A CN111987907 A CN 111987907A
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terminal
coupled
comparator
power supply
mode power
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阮剑聪
谭润钦
P·朱
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Texas Instruments Inc
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Texas Instruments Inc
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Priority claimed from US16/654,132 external-priority patent/US11463002B2/en
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Publication of CN111987907A publication Critical patent/CN111987907A/en
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    • H—ELECTRICITY
    • H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
    • H02M—APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF
    • H02M3/00—Conversion of dc power input into dc power output
    • H02M3/02—Conversion of dc power input into dc power output without intermediate conversion into ac
    • H02M3/04—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters
    • H02M3/10—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode
    • H02M3/145—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal
    • H02M3/155—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only
    • H02M3/156—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators
    • H02M3/158—Conversion of dc power input into dc power output without intermediate conversion into ac by static converters using discharge tubes with control electrode or semiconductor devices with control electrode using devices of a triode or transistor type requiring continuous application of a control signal using semiconductor devices only with automatic control of output voltage or current, e.g. switching regulators including plural semiconductor devices as final control devices for a single load

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  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Dc-Dc Converters (AREA)

Abstract

A switched mode power supply circuit (500) includes a feedback terminal (502B), a control circuit (512), a comparator (514), and a switch (516). The comparator (514) includes a first input terminal (514A) coupled to the reference voltage source (526) and an output terminal (514C) coupled to the input terminal (512D) of the control circuit (512). The switch (516) includes a first terminal (516A) coupled to the feedback terminal (502B), a second terminal (516B) coupled to the second input terminal (514B) of the comparator (514), and a third terminal (516C) coupled to the output terminal (512C) of the control circuit (512).

Description

Switch mode power supply circuit
Cross Reference to Related Applications
This application claims priority from U.S. provisional patent application No. 62/852,436 entitled "a DC-DC Converter with Improved Noise Immunity," filed 24/5/2019, which is incorporated herein by reference in its entirety.
Background
A switched mode power supply is an electronic circuit that converts an input Direct Current (DC) supply voltage into one or more DC output voltages having a magnitude higher or lower than the input DC supply voltage. Switched mode power supplies that generate an output voltage that is lower than the input voltage are referred to as buck converters or buck converters. A switched mode power supply that generates an output voltage higher than the input voltage is called a boost converter or a boost converter.
Some switch-mode power supply topologies include a drive/power transistor coupled to an energy storage inductor/transformer at a switching node. By alternately opening and closing the switch in accordance with the switching signal, electrical energy is transferred through the energy storage inductor/transformer to the load. The amount of electrical energy delivered to the load is a function of the on/off duty cycle of the switch and the frequency of the switching signal. Switched mode power supplies are widely used in electronic devices, especially battery powered devices such as portable cellular telephones, laptop computers, and other electronic systems where efficient use of power is required.
Disclosure of Invention
A switched mode power supply circuit is disclosed that reduces the undesirable effects of switching noise during circuit operation by blanking (blanking) the feedback voltage during transistor switching. In one example, a switched mode power supply circuit includes a feedback terminal, a control circuit, a comparator, and a switch. The comparator includes a first input terminal coupled to a reference voltage source and an output terminal coupled to the control circuit. The switch includes a first terminal coupled to the feedback terminal, a second terminal coupled to the second input terminal of the comparator, and a third terminal coupled to the control circuit.
In another example, a switched mode power supply circuit includes a feedback terminal, a comparator, a switch, and a control circuit. The feedback terminal is configured to receive a feedback signal. The comparator is configured to compare the feedback signal with a reference signal. The switch is coupled to the feedback terminal and the comparator and is configured to pass the feedback signal from the feedback terminal to the comparator. The control circuit is coupled to the comparator and configured to generate a control signal to turn on the high-side transistor to open the switch before an edge of the control signal and to close the switch after the edge of the control signal.
In another example, a switched mode power supply includes an inductor, a high side transistor, a low side transistor, a voltage divider, a control circuit, a comparator, and a switch. The high-side transistor, the low-side transistor, and the voltage divider are coupled to the inductor. The control circuit includes a first output terminal coupled to the high-side transistor and a second output terminal coupled to the low-side transistor. The comparator includes a first input terminal coupled to a reference voltage source and an output terminal coupled to an input terminal of the control circuit. The switch includes a first terminal coupled to the voltage divider, a second terminal coupled to the second input terminal of the comparator, and a third terminal coupled to the third output terminal of the control circuit.
In yet another example, an electricity meter includes metering circuitry and a switch mode power supply. A switch mode power supply is coupled to the metering circuitry and includes an inductor, a high side transistor, a low side transistor, a voltage divider, a control circuit, a comparator, and a switch. The high-side transistor, the low-side transistor, and the voltage divider are coupled to the inductor. The control circuit includes a first output terminal coupled to the high-side transistor and a second output terminal coupled to the low-side transistor. The comparator includes a first input terminal coupled to a reference voltage source and an output terminal coupled to an input terminal of the control circuit. The switch includes a first terminal coupled to the voltage divider, a second terminal coupled to the second input terminal of the comparator, and a third terminal coupled to the third output terminal of the control circuit.
Drawings
For a detailed description of various examples, reference will now be made to the accompanying drawings in which:
FIG. 1 illustrates an isometric perspective view of an integrated circuit package suitable for use in a switched mode power supply in accordance with the present description;
FIG. 2 illustrates output switching coupled to a feedback voltage in a switched mode power supply circuit;
FIG. 3 illustrates subharmonic oscillations caused by output switching coupled to a feedback voltage in a switched mode power supply circuit;
FIG. 4 illustrates an exemplary low pass filter applied to attenuate the effects of output switching coupled to a feedback voltage in a switch mode power supply circuit;
FIG. 5 illustrates a block diagram of an exemplary switched mode power supply including blanking to eliminate coupling of output switching on a feedback voltage in accordance with the present description;
fig. 6 shows an example of blanking applied in the switched mode power supply of fig. 5 when the switching signal active time is longer than the blanking time;
fig. 7 shows an example of blanking applied in the switched mode power supply of fig. 5 when the switching signal active time is shorter than the blanking time;
fig. 8 shows an example of blanking applied in the switched mode power supply of fig. 5 when the switching signal inactive time is shorter than the blanking time;
FIG. 9 illustrates exemplary signals generated in the switched mode power supply of FIG. 5; and
FIG. 10 illustrates a block diagram of an exemplary electricity meter including a switched mode power supply in accordance with the subject specification.
Detailed Description
A switch mode power supply operating in a buck mode includes a high-side transistor and a low-side transistor coupled in series between a voltage input node and a ground node and joined at a switch node. An output circuit is coupled to the switching node for generating an output voltage based on a switching signal generated at the switching node. The switched mode power supply further comprises a feedback node configured to receive a feedback signal based on the output voltage. During operation, a control circuit of the switched mode power supply generates control signals to turn on and off the high-side transistor and the low-side transistor with respect to each other, the control signals generating switching signals at the switching node. A ripple voltage generated based on the switching signal at the switching node is coupled to the feedback signal. A switching signal is generated based on a difference between the reference voltage and the feedback signal in combination with the ripple voltage.
As integrated circuits and integrated circuit packages become smaller, the pitch between the pins shrinks, which increases the parasitic capacitance between the pins. Fig. 1 shows an isometric perspective view of an integrated circuit package 100 suitable for use in a switched mode power supply in accordance with the present description. The integrated circuit package 100 includes a pin 104 for coupling the high-side transistor and the low-side transistor to the inductor and a pin 106 for receiving a feedback voltage. Parasitic capacitance 102 is shown between pin 104 and pin 106. As package size decreases, parasitic capacitance 102 increases and coupling between the switching signal provided on pin 104 and the feedback signal received at pin 106 increases.
Fig. 2 shows coupling a switching signal to a feedback voltage in the integrated circuit package 100. The switching signal (not shown) switches at a frequency of about 500 kHz. Switching produces approximately 250 millivolts of noise on the feedback signal 202 at the edges of the switching signal. The switching noise coupled to the feedback signal 202 produces an unexpected voltage ramp at the pin 106, which causes sub-harmonic oscillations and a shift in the output voltage. Fig. 3 shows subharmonic oscillations caused by output switching coupled to a feedback voltage in a switched mode power supply circuit. In fig. 3, current 302 is the current flowing in the inductor of the switched mode power supply. The switching signal 304 is provided at a pin 104 of the integrated circuit package 100, the pin 104 being coupled to the inductor. The feedback signal 306 is proportional to the output voltage of the switched mode power supply and includes switching noise at the edges of the switching signal 304. Based on the feedback signal 306 after the low pass filter, an internal feedback signal 308 is generated at an internal feedback node of circuitry disposed in the integrated circuit package 100. An exemplary low pass filter may include a 40 kilo-ohm resistor coupled to a 2 picofarad capacitor. Even with low pass filtering, the internal feedback signal 308 is disturbed by switching noise. The switching noise in the internal feedback signal 308 causes sub-harmonic oscillations in the switched mode power supply.
Some switched mode power supplies attempt to reduce the effects of cross-coupled switching noise by lowering the breakover frequency of the low pass filter. Fig. 4 shows that a low pass filter is applied to attenuate the effect of output switching coupled to the feedback voltage in a switched mode power supply circuit. However, lowering the breakover frequency of the low pass filter reduces the system bandwidth and transient performance, which is unacceptable in some applications.
Fig. 5 shows a block diagram of an exemplary switched mode power supply 500 that includes blanking to eliminate output switching coupled to the feedback voltage. The switched mode power supply 500 includes a switched mode power supply circuit 502, an inductor 504 and a voltage divider 506. The switching terminal 502A is coupled to an inductor 504. An inductor 504 is coupled to the voltage divider 506 to divide the output voltage of the switched mode power supply 500 by a predetermined divisor to generate a feedback signal 544. A voltage divider 506 is coupled to the feedback terminal 502B to provide output voltage feedback to the switched mode power supply circuit 502. The switched mode power supply circuit 502 may be implemented in the integrated circuit package 100 or similar package.
The switched mode power supply circuit 502 includes a high side transistor 508, a low side transistor 510, a control circuit 512, a comparator 514, a switch 516, a capacitor 518, a capacitor 520, a resistor 522, a resistor 524, a voltage reference circuit 526, and a clock generator 528. Clock generator 528 is coupled to control circuit 512 and generates a clock signal. Activation of the clock signal causes the control circuit 512 to deactivate the control signal 538 and turn off the low-side transistor 510 and activate the control signal 540 and turn on the high-side transistor 508. Comparator 514 is also coupled to control circuit 512. Comparator 514 compares the feedback from voltage divider 506 to a reference voltage generated by voltage reference circuit 526. Activation of the comparator output signal 530 causes the control circuit 512 to deactivate the control signal 540 and turn off the high-side transistor 508, and activate the control signal 538 and turn on the low-side transistor 510.
The control circuit 512 includes an output terminal 512A and an output terminal 512B. The output terminal 512A is coupled to a gate terminal 508G of the high-side transistor 508 to turn the high-side transistor 508 on and off via a control signal 540. The output terminal 512B is coupled to the gate terminal 510G of the low-side transistor 510 to turn the low-side transistor 510 on and off via the control signal 538. The drain terminal 508D of the high-side transistor 508 is coupled to the power rail 532 and the source terminal 508S of the high-side transistor 508 is coupled to the switching terminal 502A to provide a charging current to the inductor 504 when the high-side transistor 508 is on. The drain terminal 510D of the low side transistor 510 is coupled to the switching terminal 502A, and the source terminal 510S of the low side transistor 510 is coupled to a common voltage source 534 (such as ground) to discharge the inductor 504 when the low side transistor 510 is on.
The comparator 514 includes an output terminal 514C coupled to the input terminal 512D of the control circuit 512 for providing a result of the comparison of the reference signal 552 with the feedback signal 544. The comparator 514 also includes an input terminal 514A coupled to the voltage reference circuit 526 via a resistor 522 to receive a reference signal 552 for comparison with the feedback signal 544. Resistor 522 includes a terminal 522B coupled to a terminal 522A of voltage reference circuit 526 and to an input terminal 514A of comparator 514 for providing a reference signal 552 (which is derived from the output of voltage reference circuit 526 to comparator 514). The resistor 524 includes a terminal 524A coupled to the input terminal 514A of the comparator 514 and a terminal 524B coupled to a reference voltage source, such as ground for setting the voltage of the reference signal 522 with the resistor 522. An input terminal 514B of the comparator 514 is coupled to the voltage divider 506 via a switch 516. Input terminal 514B is coupled to a terminal 516B of switch 516 for receiving feedback signal 544 when switch 516 is closed. A terminal 516A of the switch 516 is coupled to the voltage divider 506 via a feedback terminal 502B for providing a feedback signal 544 to the switch 516 and the comparator 514. A terminal 516C of the switch 516 is coupled to an output terminal 512C of the control circuit 512 for opening and closing the switch 516 with respect to edges of a control signal 538 and a control signal 540 generated by the control circuit 512. Blanking control signal 536 generated by control circuit 512 controls switch 516.
The capacitor 518 is coupled to the comparator 514 and the switch 516, and when the switch 516 is closed, the voltage across the capacitor 518 follows the voltage at the feedback terminal 502B. The capacitor 518 includes a terminal 518B coupled to ground and a terminal 518A coupled to the input terminal 514B of the comparator 514 and the terminal 516B of the switch 516 to track the voltage of the feedback signal 544 when the switch 516 is closed and to maintain the voltage of the feedback signal 544 when the switch 516 is open.
Capacitor 520 is coupled to input terminal 514A and input terminal 514B of comparator 514 and forms a low pass filter circuit with resistor 522 and resistor 524. Terminal 520A of capacitor 520 is coupled to input terminal 514A of comparator 514 and terminal 520B of capacitor 520 is coupled to input terminal 514B of comparator 514 to provide a path for high frequency signals between input terminal 514A and input terminal 514B of comparator 514. The pole frequency of the low pass filter circuit is defined as:
Figure BDA0002506141930000051
wherein:
R1is the resistance of resistor 522;
R2is the resistance of resistor 524; and is
CCIs the capacitance of capacitor 520.
The control circuit 512 deactivates the blanking control signal 536 to open the switch 516 when the high-side transistor 508 or the low-side transistor 510 transitions between the on state and the off state. For example, control circuit 512 deactivates blanking control signal 536 before deactivating control signal 540 and activates blanking control signal 536 after subsequently activating control signal 538. Similarly, control circuit 512 deactivates blanking control signal 536 before deactivating control signal 538 and activates blanking control signal 536 after subsequently activating control signal 540. Since the switch 516 is open during the transition at the switching terminal 502A, there is no noise at the input terminal 514B of the comparator 514 that is induced at the feedback terminal 502B by the transition. The capacitor 518 provides a sample of the feedback signal 544 at the input terminal 514B of the comparator 514 when the switch 516 is open. In some implementations of 502, delays in gate driver circuit 548 and gate driver circuit 550 may ensure that switch 516 is open prior to the transition of switching signal 542. For example, if the control signal 540 is activated while the blanking control signal 536 is deactivated, the switch 516 may be turned off before switching the high-side transistor 508 due to a delay in the gate driver circuit 548.
Fig. 6 shows an example of blanking applied in the switched mode power supply 500 when the active time of the switching signal 542 is longer than the blanking time. At 602, control circuit 512 deactivates blanking control signal 536 to open switch 516. After the switch 516 is turned off, at 610, the control circuit 512 turns off the low-side transistor 510 and turns on the high-side transistor 508 to activate the switching signal 542 at the switching terminal 502A. At a predetermined blanking interval (Tblk) after 602 (after the noise induced at the feedback terminal 502B has stabilized by the transition of the switching signal 542 at 610), the control circuit 512 activates the blanking control signal 536 to close the switch 516 at 604.
At 606, control circuit 512 deactivates blanking control signal 536 to open switch 516. After the switch 516 is turned off, at 612, the control circuit 512 turns off the high-side transistor 508 and turns on the low-side transistor 510 to deactivate the switching signal 542 at the switching terminal 502A. At a predetermined blanking interval after 606 (after the noise induced at the feedback terminal 502B has stabilized by the transition of the switching signal 542 at 612), the control circuit 512 activates the blanking control signal 536 to close the switch 516 at 608.
Fig. 7 shows an example of blanking applied in the switched mode power supply 500 when the active time of the switching signal 542 is shorter than the blanking time. At 702, control circuit 512 deactivates blanking control signal 536 to open switch 516. After the switch 516 is turned off, the control circuit 512 turns off the low-side transistor 510 and turns on the high-side transistor 508 to activate the switching signal 542 at the switching terminal 502A at 706. At 708, the control circuit 512 turns off the high-side transistor 508 and turns on the low-side transistor 510 to deactivate the switching signal 542 at the switching terminal 502A. At a predetermined blanking interval after 708 (after the noise induced at the feedback terminal 502B has stabilized by the transition of the switching signal 542 at 706 and 708), the control circuit 512 activates the blanking control signal 536 to close the switch 516 at 704.
Fig. 8 shows an example of blanking applied in the switched mode power supply 500 when the inactive time of the switching signal 542 is shorter than the blanking time. At 802, control circuit 512 deactivates blanking control signal 536 to open switch 516. After the switch 516 is turned off, at 806, the control circuit 512 turns off the high-side transistor 508 and turns on the low-side transistor 510 to deactivate the switching signal 542 at the switching terminal 502A. At 808, the control circuit 512 turns off the low-side transistor 510 and turns on the high-side transistor 508 to activate the switching signal 542 at the switching terminal 502A. At a predetermined blanking interval after 808 (after the noise induced at the feedback terminal 502B has stabilized by the transition of the switching signal 542 at 806 and 808), the control circuit 512 activates the blanking control signal 536 to close the switch 516 at 804.
In the examples of fig. 6-8, the length of the blanking interval is determined based on the setup time of the feedback signal at the feedback terminal 502B. For example, the blanking interval may be longer than the settling time of the feedback signal at the feedback terminal 502B and short enough to ensure that the feedback signal can be sensed in a single cycle of the switched mode power supply 500.
Fig. 9 shows example signals generated in a switched mode power supply 500. At 902, control circuit 512 deactivates blanking control signal 536 to open switch 516. After the switch 516 is turned off, at 904, the control circuit 512 turns off the low-side transistor 510 and turns on the high-side transistor 508 to activate the switching signal 542 at the switching terminal 502A. When the high-side transistor 508 is turned on (in interval 922), the current 902 in the inductor 504 increases. At a predetermined blanking interval after 904 (after the noise transient 914 induced in the feedback signal 544 at the feedback terminal 502B by the transition of the switching signal 542 at 904 has stabilized), the control circuit 512 activates the blanking control signal 536 at 906 to close the switch 516.
At 908, control circuit 512 deactivates blanking control signal 536 to open switch 516. After the switch 516 is turned off, at 910, the control circuit 512 turns off the high-side transistor 508 and turns on the low-side transistor 510 to deactivate the switching signal 542 at the switching terminal 502A. At a predetermined blanking interval after 910 (after the noise transient 916 induced at the feedback terminal 502B by the transition of the switching signal 542 at 910 has stabilized), the control circuit 512 activates the blanking control signal 536 to close the switch 516 at 912.
Because switch 516 is open when noise transient 914 and noise transient 916 are present at feedback terminal 502B, noise transient 914 and noise transient 916 are not present on internal feedback voltage 546 at input terminal 514B of comparator 514. The difference signal 924 represents the difference of the reference signal 552 at the input terminal 514A of the comparator 514 and the internal feedback voltage 546 at the input terminal 514B of the comparator 514. In the difference signal 924, in interval 918, the noise transient 914 is not present, and in interval 920, the noise transient 916 is not present. Thus, noise transients 914 and 916 do not cause sub-harmonic oscillations in switch mode power supply 500. In addition, parasitic inductance caused by ground noise between the printed circuit board on which the switch mode power supply circuit 502 is mounted and the ground is attenuated.
The switched mode power supply control circuitry described herein provides a number of advantages over other solutions. The blanking and filtering circuitry of the switched mode power supply circuit 502 is relatively simple to implement and effectively filters the disturbance in the feedback signal 544 caused by the transition of the switching signal 542 and senses the undisturbed feedback signal 544 in the absence of transient noise. The switched mode power supply circuit 502 does not sacrifice transient performance by reducing the transition frequency of the low pass filter applied to the feedback signal. Because the internal feedback voltage 546 is static when the switch 516 is open (during the blanking time), jitter performance is improved. The embodiment of 500 is stable even in embodiments that are not optimal for Printed Circuit Board (PCB) routing and that employ small integrated circuit packages, which allows for flexible packaging and PCB routing.
FIG. 10 illustrates a block diagram of an exemplary electricity meter 1000 including a switched mode power supply in accordance with the subject specification. The electric meter 1000 is a smart meter that measures the ac current drawn from the mains supply and communicates the measurement to the electricity supplier. The electricity meter 1000 includes an AC/DC converter 1002, battery circuitry 1004, a DC/DC converter 1006, metering circuitry 1008, a processor 1010, user interface circuitry 1012, and communication circuitry 1014. The AC/DC converter 1002 includes circuitry to convert an alternating voltage received from a main power source to a direct voltage. The battery circuitry 1004 includes a battery and switching circuitry to switch the output of the battery or AC/DC converter 1002 to the DC/DC converter 1006.
The DC/DC converter 1006 generates one or more DC voltages from the DC voltage received by the battery circuitry 1004 that power the metering circuitry 1008, the processor 1010, the user interface circuitry 1012, and the communication circuitry 1014. Metering circuitry 1008 includes circuitry such as a current sensor and an analog-to-digital converter that measures the ac current drawn from the ac mains by the electrical devices coupled to the electric meter 1000. Metering circuitry 1008 communicates the current measurements to processor 1010. Processor 1010 includes a microcontroller or other instruction execution device that stores and/or communicates measurements via communication circuitry 1014 and/or user interface circuitry 1012. The user interface circuitry 1012 may include a display device, such as a liquid crystal display, and an input device, such as a keyboard. The communication circuitry 1014 includes wired (universal serial bus, RS-232, etc.) and/or wireless communication circuitry that allows the processor 1010 to communicate measurements and other information to the power provider.
The DC/DC converter 1006 includes an embodiment of the switched mode power supply 500. The feedback blanking circuitry included in the switched mode power supply circuit 502 allows for a reduction in the size of the integrated circuit package, which reduces the size and cost of the power meter 1000 while eliminating subharmonic oscillations without sacrificing transient performance. Thus, the DC/DC converter 1006 can respond quickly to changes in load current. Because the DC/DC converter 1006 is not affected by transients coupled from the switching signal 542 to the feedback signal 544, PCB wiring in the DC/DC converter 1006 and packaging of the electricity meter 1000 may be simplified.
The term "coupled" is used throughout the specification. The term may encompass a connection, communication, or signal path that achieves a functional relationship consistent with the description of the present disclosure. For example, if device a generates a signal to control device B to perform an action, then in a first example, device a is coupled to device B through a direct connection, or in a second example, device a is coupled to device B through intermediate component C if intermediate component C does not alter the functional relationship between device a and device B such that device a controls device B via the control signal generated by device a.
Modifications may be made in the described embodiments within the scope of the claims, and other embodiments are possible.

Claims (21)

1. A switched mode power supply circuit, comprising:
a feedback terminal;
a control circuit;
a comparator, comprising:
a first input terminal coupled to a reference voltage source; and
an output terminal coupled to an input terminal of the control circuit; and
a switch, comprising:
a first terminal coupled to the feedback terminal;
a second terminal coupled to a second input terminal of the comparator; and
a third terminal coupled to an output terminal of the control circuit.
2. The switched mode power supply circuit of claim 1, further comprising: a capacitor, comprising:
a first terminal coupled to the first input terminal of the comparator; and
a second terminal coupled to the second input terminal of the comparator.
3. The switched mode power supply circuit of claim 2, further comprising: a resistor, comprising:
a first terminal coupled to the reference voltage source; and
a second terminal coupled to the first terminal of the comparator.
4. The switched mode power supply circuit of claim 3, wherein:
the resistor is a first resistor; and is
The switched mode power supply circuit further comprises:
a second resistor, comprising:
a first terminal coupled to the first terminal of the comparator; and
a second terminal coupled to a common voltage source.
5. The switched mode power supply circuit of claim 1, further comprising: a capacitor, comprising:
a first terminal coupled to the second input terminal of the comparator; and
a second terminal coupled to a common voltage source.
6. The switched mode power supply circuit of claim 1, further comprising:
a switching terminal;
a high-side transistor, comprising:
a first terminal coupled to the control circuit;
a second terminal coupled to a power rail; and
a third terminal coupled to the switching terminal; and
a low-side transistor comprising:
a first terminal coupled to the control circuit;
a second terminal coupled to the switching terminal; and
a third terminal coupled to a common voltage source.
7. The switched mode power supply circuit of claim 6, wherein the control circuit is configured to:
generating a control signal to control the high-side transistor;
opening the switch before an edge of the control signal; and is
Closing the switch after the edge of the control signal.
8. The switched mode power supply circuit of claim 7, wherein:
the control signal is a first control signal; and is
The control circuit is configured to:
generating a second control signal that controls the low-side transistor;
opening the switch before an edge of the second control signal; and is
Closing the switch after the edge of the second control signal.
9. The switched mode power supply circuit of claim 8, wherein the control circuit is configured to:
opening the switch before the edge of the first control signal; and is
Closing the switch after the edge of the second control signal.
10. A switched mode power supply circuit, comprising:
a feedback terminal configured to receive a feedback signal;
a comparator configured to compare the feedback signal with a reference signal;
a switch coupled to the feedback terminal and the comparator and configured to pass the feedback signal from the feedback terminal to the comparator; and
a control circuit coupled to the comparator and configured to:
generating a control signal to turn on the high-side transistor; and is
Opening the switch before an edge of the control signal; and is
Closing the switch after the edge of the control signal.
11. The switched mode power supply circuit of claim 10, wherein:
the control signal is a first control signal; and is
The control circuit is configured to:
generating a second control signal that turns on a low-side transistor; and is
Opening the switch before an edge of the second control signal; and is
Closing the switch after the edge of the second control signal.
12. The switched mode power supply circuit of claim 11, wherein the control circuit is configured to:
opening the switch before the edge of the first control signal; and is
Closing the switch after the edge of the second control signal.
13. The switched mode power supply circuit of claim 10, further comprising a filter circuit configured to attenuate noise on the feedback signal.
14. The switched mode power supply circuit of claim 13, wherein the filter circuit comprises:
a capacitor coupled to a first input of the comparator and a second input of the comparator;
a first resistor coupled to the first input of the comparator and a reference voltage source; and
a second resistor coupled to the first input of the comparator and a common voltage source.
15. The switched mode power supply circuit of claim 10, further comprising a capacitor coupled to the comparator and a reference voltage source and configured to provide a sample of the feedback signal to the comparator when the switch is open.
16. A switched mode power supply, comprising:
an inductor;
a high-side transistor coupled to the inductor;
a low side transistor coupled to the inductor;
a voltage divider coupled to the inductor;
a control circuit, comprising:
a first output terminal coupled to the high-side transistor; and
a second output terminal coupled to the low-side transistor;
a comparator, comprising:
a first input terminal coupled to a reference voltage source; and
an output terminal coupled to an input terminal of the control circuit; and
a switch, comprising:
a first terminal coupled to the voltage divider;
a second terminal coupled to a second input terminal of the comparator; and
a third terminal coupled to a third output terminal of the control circuit.
17. The switched mode power supply of claim 16, further comprising:
a capacitor, comprising:
a first terminal coupled to the second input terminal of the comparator; and
a second terminal coupled to a common voltage source.
18. The switched mode power supply of claim 16, further comprising:
a capacitor, comprising:
a first terminal coupled to the first input terminal of the comparator; and
a second terminal coupled to the second input terminal of the comparator.
19. The switched mode power supply of claim 18, further comprising:
a resistor, comprising:
a first terminal coupled to the reference voltage source; and
a second terminal coupled to the first terminal of the comparator.
20. The switched mode power supply of claim 19, wherein:
the resistor is a first resistor; and is
The switched mode power supply further comprises:
a second resistor, comprising:
a first terminal coupled to the first terminal of the comparator; and
a second terminal coupled to a common voltage source.
21. An electricity meter, comprising:
a metering circuitry; and
a switched mode power supply coupled to the metering circuitry and comprising:
an inductor;
a high-side transistor coupled to the inductor;
a low side transistor coupled to the inductor;
a voltage divider coupled to the inductor;
a control circuit, comprising:
a first output terminal coupled to the high-side transistor; and
a second output terminal coupled to the low-side transistor;
a comparator, comprising:
a first input terminal coupled to a reference voltage source; and
an output terminal coupled to an input terminal of the control circuit; and a switch, comprising:
a first terminal coupled to the voltage divider;
a second terminal coupled to a second input terminal of the comparator; and
a third terminal coupled to a third output terminal of the control circuit.
CN202010446658.0A 2019-05-24 2020-05-25 Switch mode power supply circuit Pending CN111987907A (en)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US201962852436P 2019-05-24 2019-05-24
US62/852,436 2019-05-24
US16/654,132 2019-10-16
US16/654,132 US11463002B2 (en) 2019-05-24 2019-10-16 Switch-mode power supply circuit

Publications (1)

Publication Number Publication Date
CN111987907A true CN111987907A (en) 2020-11-24

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Family Applications (1)

Application Number Title Priority Date Filing Date
CN202010446658.0A Pending CN111987907A (en) 2019-05-24 2020-05-25 Switch mode power supply circuit

Country Status (1)

Country Link
CN (1) CN111987907A (en)

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