Method and apparatus providing final test and trimming for a power supply controller

• US 6,388,853 B1
• Filed: 09/28/1999
• Issued: 05/14/2002
• Est. Priority Date: 09/28/1999
• Status: Expired due to Term

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Balakrishnan, Balu, Bircan, Erdem, Djenguerian, Alex B.
• Primary Examiner(s): HUYNH, KIM NGOC
• Application Number:
  US09/407,609
• Time in Patent Office: 959 Days
• Field of Search: 361/103, 361/93.1, 361/93.8, 361/93.9, 361/78, 361/86, 327/306, 327/309, 327/317, 327/530, 327/525, 327/86, 327/585, 702/99, 702/57, 702/64, 702/65, 702/116, 324/105, 323/907
• US Class Current: 361/93.9
• CPC Class Codes: G06F 1/26 Power supply means, e.g. regulation thereof for memories G11C
• CPC Class Codes: G11C 29/02 Detection or location of defective auxiliary circuits, e.g. defective refresh counters
• CPC Class Codes: G11C 29/021 in voltage or current generators
• CPC Class Codes: H02M 1/32 Means for protecting converters other than automatic disconnection
• CPC Class Codes: H02M 1/36 Means for starting or stopping converters
• CPC Class Codes: H02M 3/00 Conversion of dc power input into dc power output
• CPC Class Codes: H02M 3/157 with digital control

Abstract

A power supply controller having final test and trim circuitry. In one embodiment, a power supply controller for switched mode power supply includes a selector circuit, a trim circuit, a shutdown circuit and a disable circuit. The trim circuit includes a programmable circuit connection that can be selected by the selector circuit by toggling a voltage on an external terminal such as for example a power supply terminal, a control terminal or a function terminal of the power supply controller. The programmable circuit connection in the trim circuit can be programmed by applying a programming voltage to the external terminal. The shutdown circuit shuts down the power supply controller if the temperature rises above an over temperature threshold voltage. The shutdown circuit includes adjustment circuitry that can be used to test the shutdown circuit. The adjustment circuitry can adjust and reduce the over temperature threshold of the power supply controller. Thus, the power supply controller can be tested without having to actually heat the part. The disable circuit includes a programmable circuit connection, which when programmed prevents further trimming of power supply controller and prevents adjustment of the shutdown circuit over temperature threshold.

Claims

1. A power supply controller circuit, comprising:

an external terminal, the external terminal is one of a power supply terminal, a control terminal and a function terminal of the power supply controller circuit;

one or more trim circuits coupled to the external terminal, each of the one or more trim circuits including a programmable circuit connection to be programmed in response to a signal on the external terminal; and

a disable circuit coupled to the external terminal and the one or more trim circuits, the disable circuit including another programmable circuit connection, when programmed the disable circuit to disable the programmable circuit connections of each of the one or more trim circuits from being programmed in response to the signal on the external terminal.

2. The power supply controller circuit of claim 1 further comprising a selector circuit coupled to the external terminal and to the one or more trim circuits, the selector circuit to select a trim circuit from the one or more trim circuits to be programmed in response to the signal on the external terminal.

3. The power supply controller circuit of claim 2 wherein the power supply controller circuit is configured to operate with a first voltage at the external terminal, wherein the signal on the external terminal is to be toggled between a second voltage and a third voltage to select the trim circuit from the one or more trim circuits to be programmed.

4. The power supply controller of claim 3 wherein the signal on the external terminal is configured to apply a programming voltage to the programmable circuit connection of the selected trim circuit to pass a programming current through the programmable circuit connection of the selected trim circuit to program the programmable circuit connection of the selected trim circuit, the programming voltage greater than the third voltage.

5. The power supply controller circuit of claim 1 wherein the power supply controller circuit is an integrated circuit.

6. A power supply controller circuit, comprising:

an external terminal, the external terminal is one of a power supply terminal, a control terminal and a function terminal of the power supply controller circuit;

a shutdown circuit coupled to the external terminal, the shutdown circuit to disable the power supply controller if a temperature of the shutdown circuit rises above a first threshold temperature, the shutdown circuit including adjustment circuitry coupled to the external terminal, the adjustment circuitry configured to adjust the first threshold temperature to a second threshold temperature in response to a signal on the external terminal; and

a disable circuit coupled to the external terminal and the adjustment circuitry, the disable circuit including a programmable circuit connection configured to be programmed in response to the signal on the external terminal, the disable circuit to disable in response to the signal on the external terminal, the adjustment circuitry from adjusting the first threshold temperature to the second threshold temperature in response to the signal on the external terminal.

7. The power supply controller circuit of claim 6 wherein the adjustment circuitry is further configured to adjust the first threshold temperature to the second threshold temperature or a third threshold temperature in response to the signal on the external terminal, the first threshold temperature greater than the second threshold temperature and the second threshold temperature greater than the third threshold temperature.

8. The power supply controller circuit of claim 6 wherein the power supply controller circuit is an integrated circuit.

9. A method for providing an integrated circuit, comprising:

selecting a first trim circuit from one or more trim circuits of the integrated circuit with an external terminal of the integrated circuit, the external terminal is one of a supply terminal, a control terminal and a function terminal of the integrated circuit, wherein selecting the first trim circuit of the integrated circuit includes toggling a voltage of a signal applied to the external terminal between a low selection voltage and a high selection voltage; and

applying a programming voltage to the external terminal after selecting the first trim circuit to program a first programmable circuit connection of the first trim circuit.

10. The method for providing the integrated circuit of claim 9 wherein the integrated circuit is configured to operate with an operating voltage at the external terminal, the programming voltage greater than the operating voltage.

11. The method for providing the integrated circuit of claim 9 further comprising verifying that the first programmable circuit connection of the first trim circuit is programmed by measuring a supply current flowing through the external terminal after applying the programming voltage.

12. The method for providing the integrated circuit of claim 11 further comprising comparing the supply current flowing through the external terminal after applying the programming voltage with the supply current flowing through the external terminal before applying the programming voltage to verify that the first programmable circuit connection of the first trim circuit is programmed.

13. The method for providing the integrated circuit of claim 9 further comprising:

selecting a disable circuit of the power supply controller circuit; and

applying the programming voltage to the external terminal after selecting the disable circuit to program a second programmable circuit connection of the disable circuit, the disable circuit to disable a plurality of programmable trim circuits of the integrated circuit from being further programmed, the first trim circuit one of the plurality of trim circuits.

14. The method for providing the integrated circuit of claim 13 wherein an over temperature shutdown temperature to shut down the integrated circuit is adjusted from a second threshold temperature to a first threshold temperature after the second programmable circuit connection is programmed.

15. The method for providing the integrated circuit of claim 9 further comprising selecting an over temperature shutdown circuit of the integrated circuit with the external terminal of the integrated circuit to adjust to a third threshold temperature an over temperature shutdown temperature to shut down the integrated circuit.

16. The method of claim 9 wherein integrated circuit is a power supply controller.

17. A power supply controller circuit, comprising:

an external terminal, the external terminal is one of a power supply terminal, a control terminal and a function terminal of the power supply controller circuit;

one or more trim circuits coupled to the external terminal, each of said one or more trim circuits including a programmable circuit connection to be programmed in response to a signal on the external terminal; and

a selector circuit coupled to the external terminal and to each of said one or more trim circuits, the selector circuit to select one of said one or more trim circuits to be programmed in response to the signal on the external terminal, wherein said power supply controller circuit is configured to operate with a first voltage at the external terminal, wherein the signal on the external terminal is to be toggled between a second voltage and a third voltage to select said one of said one or more trim circuits to be programmed, wherein the signal on the external terminal is configured to apply a programming voltage to the first programmable circuit connection to pass a programming current through the first programmable circuit connection to program the first programmable circuit connection, the programming voltage greater than the third voltage.

18. A method for providing an integrated circuit, comprising:

selecting a first trim circuit from one or more trim circuits of the integrated circuit with an external terminal of the integrated circuit, the external terminal is one of a supply terminal, a control terminal and a function terminal of the integrated circuit;

applying a programming voltage to the external terminal after selecting the first trim circuit to program a first programmable circuit connection of the first trim circuit;

selecting a disable circuit of the power supply controller circuit; and

applying the programming voltage to the external terminal after selecting the disable circuit to program a second programmable circuit connection of the disable circuit, the disable circuit to disable said one or more trim circuits of the integrated circuit from being further programmed.