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

• US 6,750,640 B2
• Filed: 02/14/2002
• Issued: 06/15/2004
• Est. Priority Date: 09/28/1999
• Status: Expired due to Fees

• Current Assignee: Power Integrations Incorporated
• Original Assignee: Power Integrations Incorporated
• Inventors: Bircan, Erdem, Balakrishnan, Balu, Djenguerian, Alex B.
• Primary Examiner(s): Huynh, Kim
• Application Number:
  US10/076,851
• Publication Number:
  US 20020105372A1
• Time in Patent Office: 852 Days
• Field of Search: 361/103, 361/93.1, 361/93.8, 361/93.2, 323/283, 323/314, 323/351, 327/525, 438/15
• US Class Current: 323/314
• 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 method, comprising:

packaging an integrated circuit die including a switched mode power supply controller;

trimming permanently a parameter of the switched mode power supply controller after packaging the integrated circuit die including the switched mode power supply controller, wherein any reprogramming of the parameter is not possible once it is permanently trimmed;

switching a power switch in response to a control circuit included in the switched mode power supply controller; and

transferring energy from an input of a power supply controlled by the switched mode power supply controller to an output of the power supply in response to the switching of the power switch.

2. The method of claim 1 wherein trimming the parameter of the switched mode power supply controller comprises:

selecting a first trim circuit of the switched mode power supply controller with an external terminal of the switched mode power supply controller, wherein the external terminal is one of a power supply terminal, a control terminal and a function terminal of the switched mode power supply controller; 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.

3. The method of claim 2 further comprising verifying that the first programmable circuit connection is programmed.

4. The method of claim 3 wherein verifying that the first programmable circuit connection is programmed comprises:

measuring a power supply current of the switched mode power supply controller before applying the programming voltage to the external terminal; and

measuring the power supply current of the switched mode power supply controller after applying the programming voltage to the external terminal.

5. The method of claim 3 wherein verifying that the first programmable circuit connection is programmed comprises:

selecting the first trim circuit of the switched mode power supply controller with the external terminal of the switched mode power supply controller; and

measuring a power supply current of the switched mode power supply controller.