Synchronizable power supply controller and a system incorporating the same

• US 5,142,217 A
• Filed: 03/07/1991
• Issued: 08/25/1992
• Est. Priority Date: 03/07/1991
• Status: Expired due to Term

• Current Assignee: SGS-Thomson Microelectronics (STMicroelectronics NV)
• Original Assignee: SGS-Thomson Microelectronics (STMicroelectronics NV)
• Inventors: Gontowski, Walter S. Jr.
• Primary Examiner(s): BEHA JR, WILLIAM
• Application Number:
  US07/665,813
• Time in Patent Office: 537 Days
• Field of Search: 363/71, 363/72, 323/272, 323/288, 331/55, 307/269
• US Class Current: 323/272
• CPC Class Codes: G05F 1/577 for plural loads
• CPC Class Codes: G05F 1/59 including plural semiconductor devices as final control devices for a single load
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C
• CPC Class Codes: H02M 3/285 Single converters with a plurality of output stages connected in parallel parallel operation of a plurality of converters in dc distribution networks H02J1/10

Abstract

A pulse width modulated power supply controller is disclosed which is capable of generating synchronization pulses in such a manner that multiple ones of such power supply controllers in a system are synchronized to the controller having the highest oscillation frequency, without requiring one of the controllers to be implemented as a master and the others implemented as slaves. The power supply controller includes two comparators which are coupled to receive the external capacitor voltage. A first comparator enables a fast charging circuit, such as a current source, for increasing the rate at which the capacitor is charged responsive to the capacitor voltage reaching a first threshold; a single-ended or differential synchronization pulse is also generated, and communicated to the first comparators of other power supply controllers in a multiple controller system. The second comparator, which includes hysteresis in its characteristic, turns off the fast charging circuit at the upper threshold and initiates the discharge of the capacitor. Control of the output and masking of the comparators of the controllers is also based on the operation of the first and second comparators.

Claims

1. A system comprising a plurality of power supply controllers, wherein each power supply controller comprises:

a PWM comparator for comparing a feedback signal to a commanded level;

a circuit for generating a pulse width modulated signal responsive to the output of said PWM comparator, and for applying the same to the output of the power supply controller;

a capacitor; and

an oscillator, comprising;

a first comparator having an input coupled to a first terminal, for receiving a voltage thereat and for generating an output corresponding to the comparison of said voltage with a first threshold level, said first terminal coupled to said capacitor;

a second comparator, having an input coupled to a second terminal for receiving a voltage thereat, and for generating an output corresponding to the comparison of the voltage at its input with second and third threshold level, said second comparator driving its output to a first state responsive to the voltage at its input exceeding said second threshold level and maintaining said first state until the voltage at its input falls below said third threshold level, said second threshold level being higher than said first threshold level, and said third threshold level being lower than said first threshold level, said second terminal also coupled to said capacitor;

a charging circuit for applying charging current to said capacitor responsive to said first and second comparators in such a manner that said charging circuit is enabled responsive to the voltage at the input of said first comparator exceeding said first threshold level, and is disabled responsive to the output of said second comparator at said first state; and

a pulse generator circuit, having an output coupled to the input of said first comparator, for generating a synchronization pulse responsive to the voltage at the input of said first comparator exceeding said first threshold level;

wherein said power supply controllers are connected to one another in such a manner that said synchronization pulse generated by a first of said plurality of power supply controllers is received by a second of said plurality of power supply controllers.

2. The system of claim 1, wherein said pulse generator circuit applies said synchronization pulse to said first terminal responsive to the input of said first comparator exceeding said first threshold level, said synchronization pulse having a voltage above said first threshold level;

and

wherein said first terminals of said plurality of power supply controllers are connected to one another, such that the synchronization pulse applied by a first of said plurality of power supply controllers is received at the first terminal of another of said plurality of power supply controllers.

3. The system of claim 1, wherein said pulse generator circuit applies a differential synchronization pulse to first and second sync terminals responsive to the voltage at the input of said first comparator exceeding said first threshold level;

and

wherein said first sync terminals of said plurality of power supply controllers are connected in common with one another, and wherein said second sync terminals of said plurality of power supply controllers are connected in common with one another.

4. The system of claim 3, wherein said pulse generator circuit comprises:

a differential amplifier, having inputs coupled to said first and second sync terminals, and having an output coupled to said input of said first comparator at which a pulse of a voltage higher than said first threshold level is generated responsive to said differential amplifier receiving a differential synchronization pulse at said first and second sync terminals.

5. The system of claim 1, further comprising, for each of said plurality of power supply controllers:

a first resistor coupled between said first terminal and said capacitor in such a manner that said first resistor is also coupled between said first and second terminals; and

a discharge circuit, coupled to said second terminal, for discharging the voltage thereat responsive to the output of said second comparator being at said first state.

6. The system of claim 5, further comprising, for each of said plurality of power supply controllers:

a second resistor coupled between said capacitor and said second terminal.

7. The system of claim 1, further comprising, for each of said plurality of power supply controllers:

a mask circuit, having an output coupled to a control input of said PWM comparator and having an input coupled to the output of said first comparator, for disabling said PWM comparator responsive to the voltage at the input of said first comparator exceeding said first threshold level.

8. The system of claim 7, wherein said mask circuit also has an input coupled to the output of said second comparator, and is also for enabling said PWM comparator responsive to the voltage at said second terminal falling below said third threshold level.

9. The system of claim 1, further comprising, for each of said plurality of power supply controllers:

a disable circuit, having an output coupled to a control input of said circuit for generating a pulse width modulated signal, having an input coupled to the output of said first comparator and having an input coupled to the output of said second comparator, for disabling said generating circuit responsive to responsive to the voltage at the input of said first comparator exceeding said first threshold level and for enabling said generator circuit responsive to the voltage at said second terminal exceeding said second threshold level.

10. A power supply controller, comprising:

a PWM comparator for comparing a feedback signal to a commanded level;

a circuit for generating a pulse width modulated signal responsive to the output of said PWM comparator, and for applying the same to the output of the power supply controller; and

an oscillator, comprising;

a first comparator having an input coupled to a first terminal for receiving a voltage thereat and for generating an output corresponding to the comparison of said voltage with a first threshold level;

a second comparator, having an input coupled to a second terminal for receiving a voltage thereat, and for generating an output corresponding to the comparison of the voltage at its input with second and third threshold levels, said second comparator driving its output to a first state responsive to the voltage at its input exceeding said second threshold level and maintaining said first state until the voltage at its input falls below said third threshold level, said second threshold level being higher than said first threshold level, and said third threshold level being lower than said first threshold level;

a charging circuit for applying a charging current to said first terminal responsive to said first and second comparators in such a manner that said charging circuit is enabled responsive to the voltage at the input of said first comparator exceeding said first threshold level, and is disabled responsive to the output of said second comparator at said first state, for applying a charging current to said first terminal; and

a pulse generator circuit having an output coupled to the input of said first comparator, for generating a synchronization pulse responsive to the voltage at said first terminal exceeding said first threshold level.

11. The power supply controller of claim 10, further comprising:

a capacitor coupled to said first and second terminals.

12. The power supply controller of claim 11, further comprising:

a first resistor, connected between said first terminal and said capacitor;

wherein said second terminal is coupled to said capacitor in such a manner that said first resistor is connected between said first and second terminals.

13. The power supply controller of claim 10, further comprising:

a discharge circuit, coupled to said second terminal, for discharging the voltage thereat responsive to the output of said second comparator being at said first state.

14. The power supply controller of claim 13, further comprising:

a capacitor coupled to said first and second terminals;

a first resistor connected between said first terminal and said capacitor; and

wherein said second terminal is coupled to said capacitor in such a manner that said first resistor is connected between said first and second terminals.

15. The power supply controller of claim 14, further comprising:

a second resistor, connected between said capacitor and said second terminal.

16. The power supply controller of claim 10, further comprising:

a mask circuit, having an output coupled to a control input of said PWM comparator and having an input coupled to the output of said first comparator, for disabling said PWM comparator responsive to the voltage at the input of said first comparator exceeding said first threshold level.

17. The power supply controller of claim 16, wherein said mask circuit also has an input coupled to the output of said second comparator, and is also for enabling said PWM comparator responsive to the voltage at said second terminal falling below said third threshold level.

18. The power supply controller of claim 10, wherein said pulse generator circuit applies said synchronization pulse to said first terminal responsive to the voltage at the input of said first comparator exceeding said first threshold level.

19. The power supply controller of claim 10, wherein said pulse generator circuit applies a differential synchronization pulse to first and second sync terminals responsive to the voltage at the input of said first comparator exceeding said first threshold level.

20. The power supply controller of claim 19, wherein said pulse generator circuit comprises:

a differential amplifier, having inputs coupled to said first and second sync terminals, and having an output coupled to said input of said first comparator at which a pulse of a voltage higher than said first threshold level is generated responsive to receiving said differential amplifier receiving a differential synchronization pulse at said first and second sync terminals.