Method and apparatus providing a multi-function terminal for a power supply controller

• US 6,462,971 B1
• Filed: 09/24/1999
• Issued: 10/08/2002
• Est. Priority Date: 09/24/1999
• Status: Expired due to Term

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Balakrishnan, Balu, Lund, Leif O., Djenguerian, Alex B.
• Primary Examiner(s): HAN, YOUNGHUIE JESSICA
• Application Number:
  US09/405,209
• Time in Patent Office: 1,110 Days
• Field of Search: 323/282, 323/284, 323/351, 323/299, 363/89, 363/95, 363/20, 363/21.01, 363/16, 363/15
• US Class Current: 363/95
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 3/33507 with automatic control of the output voltage or current, e.g. flyback converters H02M3/33561, H02M3/33569 take precedence

Abstract

A power supply controller having a multi-function terminal. In one embodiment, a power supply controller for switched mode power supply includes a drain terminal, a source terminal, a control terminal and a multi-function terminal. The multi-function terminal may be configured in a plurality of ways providing any one or some of a plurality of functions including on/off control, external current limit adjustments, under-voltage detection, over-voltage detection and maximum duty cycle adjustment. The operation of the multi-function terminal varies depending on whether a positive or negative current flows through the multi-function terminal. A short-circuit to ground from the multi-function terminal enables the power supply controller. A short-circuit to a supply voltage from the multi-function terminal disables the power supply controller. The current limit of an internal power switch of the power supply controller may be adjusted by externally setting a negative current from the multi-function terminal. The multi-function terminal may also be coupled to the input DC line voltage of the power supply through a resistance to detect an under-voltage condition, an over-voltage condition and/or adjust the maximum duty cycle of power supply controller. Synchronization of the oscillator of the power supply controller may also be realized by switching the multi-function terminal to power or ground at the desired times.

Claims

1. A power supply controller circuit, comprising a current input circuit coupled to receive a current representative of an input voltage, the current input circuit to generate an enable/disable signal when the current crosses a threshold having a hysteresis of greater than or equal to zero, the power supply controller to activate and deactivate the power supply in response to the enable/disable signal.

2. The power supply controller circuit of claim 1 further comprising an oscillator circuit coupled to the enable/disable signal, the oscillator circuit to start and stop generating a switching waveform in response to the enable/disable signal.

3. The power supply controller circuit of claim 2 wherein the oscillator circuit is to complete an existing cycle of the switching waveform before the oscillator is to stop generating the switching waveform in response to the enable/disable signal.

4. The power supply controller circuit of claim 2 wherein the oscillator circuit is to start a new complete cycle of the switching waveform if the oscillator circuit is to start generating the switching waveform in response to the enable/disable signal.

5. The power supply controller circuit of claim 2 further comprising a power switch coupled to a primary winding of the power supply, the power switch coupled to receive and to switch in response to the switching waveform.

6. A power supply controller circuit, comprising a current input circuit coupled to receive a current representative of an input voltage, the current input circuit to generate an enable/disable signal to activate the power supply when the current is in between a first current threshold having a first hysteresis greater than or equal to zero and second current threshold having a second hysteresis greater than or equal to zero, the second current threshold higher than the first current threshold, the current input circuit to deactivate the power supply when the current is less than the first current threshold, the current input circuit to deactivate the power supply when the current is greater than the second current threshold.

7. The power supply controller circuit of claim 6 further comprising an oscillator circuit coupled to the enable/disable signal, the oscillator circuit to start and stop generating a switching waveform in response to the enable/disable signal.

8. The power supply controller circuit of claim 7 wherein the oscillator circuit is to complete an existing cycle of the switching waveform before the oscillator is to s top generating the switching waveform in response to the enable/disable signal.

9. The power supply controller circuit of claim 7 wherein the oscillator circuit is to start a new complete cycle of the switching waveform if the oscillator circuit is to start generating the switching waveform in response to the enable/disable signal.

10. The power supply controller circuit of claim 7 further comprising a power switch coupled to a primary winding of the power supply, the power switch coupled to receive and to switch in response to the switching waveform.

11. A power supply controller circuit, comprising a current input circuit coupled to receive a current representative of an on/off control signal applied to the power supply, the current input circuit to generate a n enable/disable signal to activate the power supply when the current is in between a first current threshold having a first hysteresis greater than or equal to zero and second current threshold having a hysteresis greater than or equal to zero, the second current threshold higher than the first current threshold, the current input circuit to deactivate the power supply when the current is less than the first current threshold, the current input circuit to deactivate the power supply when the current is greater than the second current threshold.

12. A power supply controller circuit, comprising a current input circuit coupled to receive a current representative of an on/off control signal applied to a power supply, the current input circuit to generate enable/disable signal when the current crosses an on/off threshold having a hysteresis greater than or equal to zero, the power supply controller to activate and deactivate a power supply in response to the on/off control signal.

13. The power supply controller circuit of claim 12 further comprising an oscillator circuit coupled to the enable/disable signal, the oscillator circuit to start and stop generating a switching waveform in response to the on/off control signal.

14. The power supply controller circuit of claim 13 wherein the oscillator circuit is to complete an existing cycle of the switching waveform before the oscillator is to stop generating the switching waveform in response to the on/off control signal.

15. The power supply controller circuit of claim 13 wherein the oscillator circuit is to start a new complete cycle of the switching waveform if the oscillator circuit is to start generating the switching waveform in response to the on/off control signal.

16. The power supply controller circuit of claim 13 further comprising a power switch coupled to a primary winding of the power supply, the power switch coupled to receive and to switch in response to the switching waveform.

17. The power supply controller circuit of claim 12 wherein the on/off threshold has a hysteresis greater than or equal to zero.

18. A power supply controller circuit, comprising:

a current input circuit coupled to receive a current, the current input circuit to generate an enable/disable signal to deactivate a power supply when the magnitude of current crosses below an on/off threshold having a hysteresis of greater than or equal to zero, the current input circuit to activate the power supply when the current crosses above the on/off threshold, the current input circuit to generate a current limit adjustment signal in response to the current; and

a control circuit coupled to receive the current limit adjustment signal, the control circuit coupled to adjust the current limit of a current through a power switch in response to the current limit adjustment signal.

19. The power supply controller circuit of claim 18 wherein the power switch is coupled to a primary winding of the power supply.

20. The power supply controller circuit of claim 19 wherein the control circuit is a pulse width modulation circuit that generates a switching waveform coupled to be received by the power switch to regulate the power supply output.

21. The power supply controller of claim 20 wherein the current is representative of a feedback signal from the power supply output, wherein the power supply voltage is regulated through current limit adjustment of the power switch in response to the feedback signal.