Power converter, clock module and associated control method

• US 9,231,574 B2
• Filed: 09/05/2014
• Issued: 01/05/2016
• Est. Priority Date: 09/05/2013
• Status: Active Grant

• Current Assignee: Chengdu Monolithic Power Systems Company Limited (Monolithic Power Systems Incorporated)
• Original Assignee: Chengdu Monolithic Power Systems Company Limited (Monolithic Power Systems Incorporated)
• Inventors: Nguyen, James, Li, Yike
• Primary Examiner(s): PATEL, RAJNIKANT B
• Application Number:
  US14/478,957
• Publication Number:
  US 20150061628A1
• Time in Patent Office: 487 Days
• Field of Search: 323/222, 323/224, 323/272, 323282-290, 363/17, 363/21.04, 363/41, 363/89, 363/97
• US Class Current: 1/1
• CPC Class Codes: H02M 1/0019 the disturbance parameters being load current fluctuations
• CPC Class Codes: H02M 1/0041 Control circuits in which a clock signal is selectively enabled or disabled
• CPC Class Codes: H02M 3/1563 without using an external clock H02M3/158 takes precedence
• CPC Class Codes: H02M 3/1566 with means for compensating against rapid load changes, e.g. with auxiliary current source, with dual mode control or with inductance variation
• CPC Class Codes: H03K 5/135 by the use of time reference signals, e.g. clock signals
• CPC Class Codes: H03K 7/08 Duration or width modulation ; Duty cycle modulation

Abstract

A power converter and a clock module employed for providing a clock signal to the power converter. The power converter converts an input voltage to an output voltage based on at least the switching on and off of a main switch. The clock module monitors a deviation of the output voltage from its desired value and compares the deviation with a predetermined threshold window to provide a clock control signal. The clock module further regulates the clock signal in response to the clock control signal.

Claims

1. A power converter, comprising:

an input port configured to receive an input voltage;

an output port configured to provide an output voltage;

a switch module comprising a main switch configured to switch on and off in response to a pulse width modulated signal to convert the input voltage into the output voltage; and

a control module having a first control input terminal, a second control input terminal, a third control input terminal and a first control output terminal, wherein the first control input terminal is configured to receive a first feedback signal indicative of the output voltage, and wherein the second control input terminal is configured to receive a second feedback signal indicative of a switching current flowing through the switch module, and wherein the third control input terminal is configured to receive a reference signal indicative of a desired value of the output voltage, and wherein

the control module is configured to provide an off trigger signal based on the first feedback signal, the second feedback signal and the reference signal; and

wherein

the control module is further configured to monitor a deviation of the output voltage from the desired value of the output voltage, and to compare the deviation with a first predetermined threshold window to generate a clock control signal, wherein the clock control signal is configured to control the generation of a clock signal, and wherein

the control module is further configured to provide the pulse width modulated signal based on the off trigger signal and the clock signal, wherein the pulse width modulated signal is configured to drive the main switch to switch on in response to the clock signal, and wherein the pulse width modulated signal is configured to drive the main switch to switch off in response to the off trigger signal.

2. The power converter of claim 1, wherein the clock control signal is configured to reset the clock signal once the deviation exceeds the first predetermined threshold window so that the clock signal can immediately trigger the pulse width modulated signal to switch the main switch on.

3. The power converter of claim 1, wherein the clock control signal is configured to vary a frequency of the clock signal during a predetermined duration once the deviation of the output voltage exceeds the first predetermined threshold window.

4. The power converter of claim 3, wherein the clock control signal is configured to increase the frequency of the clock signal from a first frequency to a second frequency immediately once the deviation of the output voltage exceeds the first predetermined threshold window, and to maintain the frequency of the clock signal at the second frequency throughout the predetermined duration, and to regulate and restore the frequency of the clock signal to the first frequency at the end of the predetermined duration.

5. The power converter of claim 3, wherein the clock control signal is configured to increase the frequency of the clock signal from a first frequency to a second frequency immediately once the deviation of the output voltage exceeds the first predetermined threshold window, and to regulate the frequency of the clock signal to gradually decrease from the second frequency to the first frequency throughout the predetermined duration.

6. The power converter of claim 1, wherein the control module further comprises:

a clock module configured to monitor the deviation of the output voltage from the desired value of the output voltage, and to compare the deviation with the first predetermined threshold window to generate the clock control signal, and to generate and regulate the clock signal based on the clock control signal.

7. The power converter of claim 6, wherein the control module further comprises:

an operational amplifier having a first amplifier input terminal configured to receive the first feedback signal, a second amplifier input terminal configured to receive the reference signal, and an amplifier output terminal configured to provide a difference signal indicative of a difference between the first feedback signal and the reference signal; and

a compensation circuit comprising a first compensation resistor and a first compensation capacitor coupled in series between the first amplifier input terminal and the amplifier output terminal; and

wherein

the clock module is configured to detect a voltage drop on the first compensation resistor to provide a voltage detection signal indicative of the deviation of the output voltage from its desired value, and to compare the voltage detection signal with a second predetermined threshold window to provide the clock control signal, wherein if the voltage detection signal exceeds the second predetermined threshold window, the clock module is configured to determine that the deviation has exceeded the first predetermined threshold window.

8. A clock module for providing a clock signal to a power converter, wherein the power converter comprises a main switch configured to switch on and off in response to a pulse width modulated signal to convert an input voltage to an output voltage, and wherein the clock module comprising:

a clock control module configured to detect a deviation of the output voltage from a desired value of the output voltage, and to compare the deviation with a first predetermined threshold window to generate a clock control signal; and

a clock generation module configured to generate the clock signal, and further configured to receive the clock control signal and to regulate the clock signal in response to the clock control signal.

9. The clock module of claim 8, wherein the clock generation module is configured to reset the clock signal in response to the clock control signal when the deviation of the output voltage exceeds the first predetermined threshold window.

10. The clock module of claim 8, wherein the clock generation module is configured to vary a frequency of the clock signal in response to the clock control signal during a predetermined duration once the deviation of the output voltage exceeds the first predetermined threshold window.

11. The clock module of claim 8, wherein once the deviation of the output voltage exceeds the first predetermined threshold window, the clock generation module is configured to increase the frequency of the clock signal immediately in response to the clock generation module from a first frequency to a second frequency, and to maintain the frequency of the clock signal at the second frequency throughout the predetermined duration, and to regulate and restore the frequency of the clock signal to the first frequency at the end of the predetermined duration.

12. The clock module of claim 8, wherein once the deviation of the output voltage exceeds the first predetermined threshold window, the clock generation module is configured to increase the frequency of the clock signal immediately in response to the clock control signal from a first frequency to a second frequency and to regulate the frequency of the clock signal to gradually decrease from the second frequency to the first frequency throughout the predetermined duration.

13. The clock module of claim 8, wherein the power converter further comprises:

an operational amplifier having a first amplifier input terminal configured to receive a first feedback signal indicative of the output voltage, a second amplifier input terminal configured to receive a reference signal indicative of the desired value of the output voltage, and an amplifier output terminal configured to provide a difference signal indicative of a difference between the first feedback signal and the reference signal; and

a compensation circuit comprising a first compensation resistor and a first compensation capacitor coupled in series between the first amplifier input terminal and the amplifier output terminal; and

wherein

the clock control module is electrically coupled to the compensation circuit to detect a voltage drop on the first compensation resistor and to provide a voltage detection signal indicative of the deviation of the output voltage, and wherein the clock control module is configured to compare the voltage detection signal with a second predetermined threshold window to provide the clock control signal, and wherein the second predetermined threshold window is indicative of the first predetermined threshold window.

14. The clock module of claim 13, wherein the clock control module comprises:

a voltage detection circuit having a first detection input terminal, a second detection input terminal and a detection output terminal, wherein the first detection input terminal is coupled to a first terminal of the first compensation resistor, the second detection input terminal is coupled to a second terminal of the first compensation resistor, and wherein the voltage detection circuit is configured to detect the voltage drop on the first compensation resistor based on the signals detected at the first detection input terminal and the second detection input terminal to provide the voltage detection signal; and

a clock control comparator having a first comparator input terminal, a second comparator input terminal and a comparator output terminal, wherein the first comparator input terminal is configured to receive the voltage detection signal, the second comparator input terminal is configured to receive a second predetermined threshold window, and wherein the clock control comparator is configured to compare the voltage detection signal with the second predetermined threshold window to provide the clock control signal.

15. The clock module of claim 13, wherein the clock control module further comprises:

a comparison circuit having a first comparison input terminal, a second comparison input terminal, a third comparison input terminal and a comparison output terminal, wherein the first comparison input terminal is coupled to the first terminal of the first compensation resistor, the second comparison input terminal is coupled to the second terminal of the first compensation resistor, and the third comparison input terminal is configured to receive the second predetermined threshold window; and

wherein

the comparison circuit is configured to directly monitor the voltages at both the first and the second terminals of the first compensation resistor to provide the voltage detection signal and to compare the voltage detection signal with the second predetermined threshold window so as to provide the clock control signal.

16. The clock module of claim 8, wherein the clock generation module comprises:

a first current source configured to provide a first constant current;

an oscillation capacitor having a first capacitor terminal and a second capacitor terminal, wherein the first capacitor terminal is coupled to the first current source to receive the first constant current, the second capacitor terminal is connected to a reference ground;

an oscillation comparator having a first comparator input terminal, a second comparator input terminal and a comparator output terminal, wherein the first comparator input terminal is electrically coupled to the first capacitor terminal of the oscillation capacitor to detect a capacitor voltage, the second comparator input terminal is configured to receive a comparison threshold, and wherein the oscillation comparator is configured to compare the capacitor voltage with the comparison threshold to provide the clock signal;

a first oscillation switch having a first switch terminal, a second switch terminal and a switch control terminal, wherein the first switch terminal is electrically coupled to the first capacitor terminal of the oscillation capacitor, the second switch terminal is connected to the reference ground, and the switch control terminal is electrically coupled to the comparator output terminal of the oscillation comparator to receive the clock signal; and

wherein the first oscillation switch is driven to switch on when the clock signal is at high logic level, and is driven to switch off when the clock signal is at low logic level;

a second current source configured to provide a second constant current, wherein the second constant current is larger than the first constant current; and

a second oscillation switch having a third switch terminal, a fourth switch terminal and a second switch control terminal, wherein the third switch terminal is electrically coupled to the second current source to receive the second constant current, the fourth switch terminal is electrically coupled to the first capacitor terminal of the oscillation capacitor, and the second switch control terminal is configured to receive the clock control signal; and

wherein if the deviation exceeds the first predetermined threshold window, the clock control signal is configured to drive the second oscillation switch to switch on and thus connecting the second current source to the first capacitor terminal of the oscillation capacitor.

17. A method for controlling a power converter, wherein the power converter comprising a main switch configured to switch on and off to convert an input voltage to an output voltage;

and wherein the method comprising;

monitoring a deviation of the output voltage from its desired value, and comparing the deviation with a first predetermined threshold window to generate a clock control signal;

regulating a clock signal of the power converter based on the clock control signal; and

switching the main switch on based on pulses of the clock signal.

18. The method of claim 17, wherein regulating the clock signal comprises:

resetting the clock signal in response to the clock control signal when the deviation exceeds the first predetermined threshold window.

19. The method of claim 17, wherein regulating the clock signal comprises:

regulating a frequency of the clock signal based on the clock control signal when the deviation exceeds the first predetermined threshold window.

20. The method of claim 17, wherein regulating the clock signal comprises:

increasing the frequency of the clock signal from a first frequency to a second frequency immediately once the deviation exceeds the first predetermined threshold window, then maintaining the frequency of the clock signal at the second frequency for a predetermined duration, and restoring the frequency of the clock signal to the first frequency at the end of the predetermined duration.