Hysteretic power converter with calibration circuit

• US 9,143,033 B2
• Filed: 11/30/2010
• Issued: 09/22/2015
• Est. Priority Date: 11/30/2010
• Status: Active Grant

• Current Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Original Assignee: Taiwan Semiconductor Manufacturing Company Limited
• Inventors: Roth, Alan, Soenen, Eric, Tai, Chia-Liang
• Primary Examiner(s): Nguyen, Matthew
• Assistant Examiner(s): DANG, TRINH Q
• Application Number:
  US12/956,630
• Publication Number:
  US 20120133345A1
• Time in Patent Office: 1,757 Days
• Field of Search: 363/56.02, 363/98, 363/16, 363/17, 323/282, 323/222, 323/259, 323/271, 323/280, 323/286, 323/344, 323/283, 323/284, 323/285, 323/288, 323/223, 323/234, 315/291, 315/294, 315/224, 315/306
• US Class Current: 1/1
• CPC Class Codes: G01R 1/203 Resistors used for electric measuring, e.g. decade resistors standards, resistors for comparators, series resistors, shunts resistors in general H01C; microwave or radiowave terminations H01P1/26; coupling devices H01R
• CPC Class Codes: G05F 1/00 Automatic systems in which deviations of an electric quantity from one or more predetermined values are detected at the output of the system and fed back to a device within the system to restore the detected quantity to its predetermined value or values, i.e. retroactive systems
• CPC Class Codes: G05F 1/10 Regulating voltage or current G05F1/02 takes precedence; for electric railways B60M3/02
• CPC Class Codes: G05F 1/40 using discharge tubes or semiconductor devices as final control devices
• CPC Class Codes: G05F 1/56 using semiconductor devices in series with the load as final control devices G05F1/461 takes precedence
• CPC Class Codes: G05F 1/575 characterised by the feedback circuit
• CPC Class Codes: H02M 3/156 with automatic control of output voltage or current, e.g. switching regulators

Abstract

A hysteretic power converter includes a comparator, a calibration circuit, and an output node having an output voltage. The calibration circuit is configured to supply a calibrated voltage to the comparator. The comparator controls the output voltage based on the calibrated voltage and a feedback voltage representing at least a portion of the output voltage.

Claims

1. A hysteretic power converter, comprising:

a first comparator which is a hysteretic comparator;

a calibration circuit;

an output node arranged to have an output voltage at a first load terminal; and

a capacitor coupled to the first load terminal and a second load terminal;

wherein

the calibration circuit is configured to supply a calibrated voltage to the first comparator,

the first comparator has

a first input configured to receive, from a feedback node, a feedback voltage representing at least a portion of the output voltage, wherein the feedback node is coupled to the second load terminal, and

a second input coupled to the calibration circuit to receive the calibrated voltage,

the calibration circuit is configured to supply the calibrated voltage processed from the feedback voltage, and

the first comparator is configured to generate, in response to a difference between the calibrated voltage processed from the feedback voltage and the feedback voltage, an output signal at a logic 1 or a logic 0 for controlling the output voltage.

2. The hysteretic power converter of claim 1, wherein the calibration circuit comprises:

a second comparator configured to receive the feedback voltage, compare the feedback voltage with a first reference voltage, and provide a calibration comparator output; and

a charge pump,

wherein the calibration comparator output is arranged to control the charge pump, and the charge pump is configured to supply the calibrated voltage.

3. The hysteretic power converter of claim 1, wherein the hysteretic power converter comprises a buck converter.

4. The hysteretic power converter of claim 1, wherein the hysteretic power converter comprises a boost converter.

5. The hysteretic power converter of claim 2, wherein the calibration circuit further comprises a voltage divider configured to divide a charge pump voltage and to supply a divided output voltage as the calibrated voltage.

6. The hysteretic power converter of claim 2, wherein the calibration circuit further comprises a voltage clamp configured to limit the calibrated voltage.

7. The hysteretic power converter of claim 2, wherein the calibration circuit further comprises a low pass filter configured to average the feedback voltage.

8. The hysteretic power converter of claim 2, wherein the charge pump comprises at least a switch and at least a current source.

9. A method of controlling a hysteretic power converter, comprising:

a feedback node supplying a feedback voltage representing at least a portion of an output voltage of the hysteretic power converter to a calibration circuit and a first input of a first comparator in the hysteretic power converter, wherein the output voltage is applied at a first load terminal, wherein the feedback node is coupled to a second load terminal, and wherein a capacitor is coupled to the first load terminal and the second load terminal;

the calibration circuit supplying a calibrated voltage processed from the feedback voltage to a second input of the first comparator; and

the first comparator generating, in response to a difference between the calibrated voltage processed from the feedback voltage and the feedback voltage, an output signal at a logic 1 or a logic 0 for controlling the output voltage,

wherein the first comparator is a hysteretic comparator.

10. The method of claim 9, further comprising:

a second comparator in the calibration circuit receiving the feedback voltage;

the second comparator comparing the feedback voltage to a reference voltage; and

supplying a calibration comparator output voltage.

11. The method of claim 9, further comprising:

a voltage clamp in the calibration circuit limiting the calibrated voltage.

12. The method of claim 9, further comprising:

a low pass filter in the calibration circuit averaging the feedback voltage.

13. The method of claim 10, further comprising:

controlling a charge pump in the calibration circuit according to the calibration comparator output voltage; and

the charge pump supplying a charge pump voltage for the calibrated voltage.

14. The method of claim 13, further comprising:

a voltage divider in the calibration circuit dividing the charge pump voltage; and

supplying a divided charge pump voltage as the calibrated voltage.

15. An integrated circuit including a hysteretic power converter, the hysteretic power converter comprising:

an output node arranged to have an output voltage at a first load terminal;

a first comparator having a first input arranged to receive, from a feedback node, a feedback voltage representing at least a portion of the output voltage, wherein the feedback node is coupled to a second load terminal;

a capacitor coupled to the first load terminal and the second load terminal;

at least one switch coupled to an output of the first comparator, the at least one switch further coupled to the output node and configured to control the output voltage;

a calibration circuit; and

a second comparator outside the calibration circuit, the second comparator configured to receive the feedback voltage and compare the feedback voltage to a first reference voltage, the second comparator having an output coupled to the at least one switch, wherein

the calibration circuit is configured to receive the feedback voltage and supply a calibrated voltage to a second input of the first comparator based on the feedback voltage, and

the first comparator and the second comparator are configured to control the at least one switch together, based on the calibrated voltage, the first reference voltage and the feedback voltage.

16. The integrated circuit of claim 15, wherein the calibration circuit comprises a third comparator configured to receive the feedback voltage, compare the feedback voltage to a second reference voltage, and provide a calibration comparator output voltage.

17. The integrated circuit of claim 15, wherein the at least one switch comprises a first switch and a second switch, the first and second switches coupled to the output node,

the integrated circuit further comprising first and second latches configured to control the corresponding first and second switches, each of the first and second latches having

a first input coupled to the output of the first comparator,

a second input coupled to the output of the second comparator, and

an output coupled to the corresponding first or second switch.

18. The integrated circuit of claim 16, wherein the calibration circuit further comprises a charge pump coupled to an output of the third comparator, the charge pump configured to supply a charge pump voltage according to the calibration comparator output voltage.

19. The integrated circuit of claim 18, wherein the calibration circuit further comprises:

a voltage divider configured to divide the charge pump voltage and supply a divided charge pump voltage as the calibrated voltage, and

a voltage clamp configured to limit the calibrated voltage.

20. The integrated circuit of claim 19, wherein the calibration circuit further comprises a low pass filter configured to average the feedback voltage supplied to the third comparator.