PSEUDO CURRENT TRACKING FOR POWER SUPPLY REGULATION

• US 20180041118A1
• Filed: 08/01/2017
• Published: 02/08/2018
• Est. Priority Date: 08/03/2016
• Status: Active Grant

• Current Assignee: Texas Instruments, Inc.
• Original Assignee: Texas Instruments, Inc.
• Inventors: COHEN, ISAAC
• Granted Patent: US 10,630,175 B2
• Time in Patent Office: Days
• CPC Class Codes: H02M 1/0009 Devices or circuits for detecting current in a converter
• CPC Class Codes: H02M 1/08 Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators
• CPC Class Codes: H02M 3/1563 without using an external clock H02M3/158 takes precedence

Abstract

A power supply circuit includes a regulation circuit that receives an input voltage and provides a regulated output voltage based on the input voltage. The regulation circuit includes a switch device having a switched output that generates a ripple current waveform in the current regulator to provide the regulated output voltage. A control circuit includes a pseudo current tracker (PCT) that is operatively coupled to the regulation circuit. The PCT receives a reference voltage and generates a ripple voltage waveform that is proportional to the ripple current waveform. The control circuit commands the switch device to generate the ripple current waveform based on the ripple voltage waveform such that the regulated output voltage approximates the reference voltage.

Claims

1. A power supply circuit, comprising:

a regulation circuit that receives an input voltage and provides a regulated output voltage based on the input voltage, the regulation circuit includes a switch device having a switched output that generates a ripple current waveform in the current regulator to provide the regulated output voltage; and

a control circuit that includes a pseudo current tracker (PCT) that is operatively coupled to the regulation circuit, the PCT receives a reference voltage and generates a ripple voltage waveform that is proportional to the ripple current waveform, the control circuit commands the switch device to generate the ripple current waveform based on the ripple voltage waveform such that the regulated output voltage approximates the reference voltage, wherein the ripple voltage waveform is proportional to the ripple current waveform if the regulated output voltage approximates the reference voltage and is not proportional if the regulated output voltage differs from the reference voltage.

2. The power supply circuit of claim 1, wherein if the regulated output voltage is less than the reference voltage, the ripple voltage waveform of the PCT has a slope that rises faster than a slope of the ripple current waveform causing the control circuit to command the switch device to turn on.

3. The power supply circuit of claim 1, wherein if the regulated output voltage is greater than the reference voltage, the ripple voltage waveform of the PCT has a slope that rises slower than a slope of the ripple current waveform which causes the control circuit to delay turning on the switch device.

4. The power supply circuit of claim 1, the control circuit further comprising an output circuit, wherein the ripple voltage waveform of the PCT is monitored by the output circuit to generate a control command to control the switch device of the regulation circuit, the control command controls a duty cycle of the switch device that defines the on time with respect to the off time of the device.

5. The power supply circuit of claim 4, wherein the output circuit includes a comparator and a flip flop, the comparator drives the flip flop to generate the control command to control the switch device, the comparator monitors the ripple voltage waveform of the PCT with respect to a peak threshold voltage, the peak threshold voltage controls the peak-to-peak amplitude of the peak ripple voltage waveform of the PCT and the peak-to-peak amplitude of the peak ripple current waveform of the current regulator.

6. The power supply circuit of claim 5, wherein the output circuit includes another comparator that monitors the ripple voltage waveform with respect to ground to generate a reset signal to the flip flop which turns the switch device off.

7. The power supply circuit of claim 1, further comprising a rectifier that is coupled to the switched output, the rectifier discharges current from the current regulator when the switch device is off.

8. The power supply circuit of claim 5, further comprising a coupling network to connect the regulation circuit to the control circuit, the coupling network includes a first resistor that couples a node of the rectifier and a negative node of the regulated output voltage to the PCT, the coupling network includes a second resistor that couples the reference voltage to the PCT, wherein the negative node of the regulated output voltage drives current though the first resistor when the switch device is on.

9. The power supply circuit of claim 8, wherein the first and second resistor of the coupling network are about equal in resistance value to set the regulated output voltage about equal to the reference voltage, the first and second resistor of the coupling network are set to different values to scale the regulated output voltage different than the reference voltage.

10. The power supply circuit of claim 8, further comprising an overload comparator to monitor the node of the rectifier with respect to ground, the comparator controls a gate that controls turn on of the switch device, the switch device turns on if the node of the rectifier becomes positive which represents when the ripple current waveform of the current regulator is at about zero amperes.

11. The power supply current of claim 1, wherein the regulation circuit and the control circuit are configured as a buck regulator, a boost regulator, or a buck/boost regulator.

12. A power supply circuit, comprising:

a regulation circuit that receives an input voltage and provides a regulated output voltage based on the input voltage, the regulation circuit includes a switch device having a switched output that drives a current regulator to provide the regulated output voltage in response to a control command, the switched output of the switch device generates a ripple current waveform in the current regulator to provide the regulated output voltage;

a control circuit having a pseudo current tracker (PCT) that is operatively coupled to the regulation circuit, the PCT receives a reference voltage and generates a ripple voltage waveform; and

an output circuit of the control circuit that monitors the ripple voltage waveform of the PCT with respect to a peak threshold voltage to generate the control command to the switch device, wherein the PCT generates the ripple voltage waveform to be proportional to the ripple current waveform, the control circuit commands the switch device to generate the ripple current waveform based on the ripple voltage waveform such that the regulated output voltage approximates the reference voltage, wherein the ripple voltage waveform is proportional to the ripple current waveform if the regulated output voltage approximates the reference voltage and is not proportional if the regulated output voltage differs from the reference voltage.

13. The power supply circuit of claim 12, wherein the output circuit includes a comparator and a flip flop, the comparator drives the flip flop to generate the control command to control the switch device, the comparator monitors the ripple voltage waveform of the PCT with respect to a peak threshold voltage, the peak threshold voltage controls the peak-to-peak amplitude of the peak ripple voltage waveform of the PCT and the peak-to-peak amplitude of the peak ripple current waveform of the current regulator.

14. The power supply circuit of claim 13, wherein the output circuit includes another comparator that monitors the ripple voltage waveform with respect to ground to generate a reset signal to the flip flop which turns the switch device off.

15. The power supply circuit of claim 12, further comprising a rectifier that is coupled to the switched output, the diode discharges current from the current regulator when the switch device is off.

16. The power supply circuit of claim 15, further comprising a coupling network to connect the regulation circuit to the control circuit, the coupling network includes a first resistor that couples a node of the rectifier and a negative node of the regulated output voltage to the PCT, the coupling network includes a second resistor that couples the reference voltage to the PCT, wherein the negative node of the regulated output voltage drives current though the first resistor when the switch device is on.

17. The power supply circuit of claim 16, wherein the first and second resistor of the coupling network are about equal in resistance value to set the regulated output voltage about equal to the reference voltage, the first and second resistor of the coupling network are set to different values to scale the regulated output voltage different than the reference voltage.

18. The power supply circuit of claim 15, further comprising an overload comparator to monitor the node of the diode with respect to ground, the comparator controls a gate that controls turn on of the switch device, the switch device turns on if the node of the diode becomes positive which represents when the ripple current waveform of the current regulator is at about a minimum current value.

19. A method, comprising:

generating a ripple current waveform in a current regulator to provide a regulated output voltage in response to a control command;

generating a ripple voltage waveform that is proportional to the ripple current waveform of the current regulator; and

controlling the regulated output voltage by commanding a switch device via the control command to generate the ripple current waveform based on the ripple voltage waveform such that the regulated output voltage approximates the reference voltage, wherein the ripple voltage waveform is proportional to the ripple current waveform if the regulated output voltage approximates the reference voltage and is not proportional if the regulated output voltage differs from the reference voltage.

20. The method of claim 19, further comprising:

commanding the switch device on if the ripple voltage waveform of the PCT has a slope that rises faster than a slope of the ripple current waveform; and

commanding the switch device off if the ripple voltage waveform of the PCT has a slope that rises slower than a slope of the ripple current waveform.