# US 6,297,661 B1 · Semiconductor switch fault detection

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- Number: US 6,297,661 B1
- Document ID: US6297661B1
- Status: Granted
- Kind: B1
- Application number: 09/294,071
- Filed: 1999-04-19
- Granted: 2001-10-02
- Earliest claimed: 1999-04-19
- Assignees: Ford Global Technologies, LLC
- Inventors: Chingchi Chen; Venkateswara Anand Sankaran
- Web page: https://patentgrep.com/patent/US6297661B1

## CPC

- G01R 19/16528: {using digital techniques or performing arithmetic operations (using digital techniques to measure a voltage or a current, see G01R19/25)}
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)

## Abstract

A system and method for detecting various fault conditions in semiconductor devices. A variable voltage reference is compared to the voltage output of the device during device turn-on to detect circuit fault conditions. The fault condition is then communicated to a controller.

## Claims

### Claim 1

A method for detecting fault conditions in a semiconductor device with its voltage drop signal that produces a voltage signal during device turn-on, the method comprising the steps of:
creating a variable reference voltage at device turn-on;
exponentially decaying the reference voltage over time down to a final reference value;
comparing a voltage from the device to the variable reference voltage; and
generating a fault condition for the device if the variable reference voltage drops below the device voltage.

### Claim 2 (depends on 1)

The method of claim 1 wherein the step of generating a fault condition includes generating the fault condition only if the device variable reference voltage drops below the device voltage during a predetermined time interval.

### Claim 3 (depends on 1)

The method of claim 1 further including the step of communicating the generated fault condition to a controller.

### Claim 4 (depends on 1)

The method of claim 1 wherein the step of creating a variable reference voltage includes creating an initial reference voltage made up of the sum of a final reference voltage, that is set greater than a final value of the device voltage, and a difference voltage, that sets an initial acceptable voltage over the final reference voltage.

### Claim 5 (depends on 4)

The method of claim 4 wherein the step of exponentially decaying includes exponentially decaying the voltage difference after the device turn-on.

### Claim 6 (depends on 1)

The method of claim 1 wherein the step of creating a variable reference voltage includes creating an initial reference voltage made up of the sum of the final reference voltage, that is set less than a final value of the device voltage, and a difference voltage, that sets an initial acceptable voltage over the final reference voltage.

### Claim 7 (depends on 6)

The method of claim 6 further including the steps of measuring an elapsed time from device turn-on until the reference voltage drops below the device voltage, and determining a deterioration of the semiconductor device based upon the elapsed time.

### Claim 8

A method for detecting fault conditions in a semiconductor device comprising the steps of:
creating a variable reference voltage at device turn-on;
exponentially decaying the reference voltage over time down to a final reference value;
comparing a voltage from the device to the variable reference voltage; and
generating a fault condition for the device if the variable reference voltage drops below the device voltage before a predetermined time has passed.

### Claim 9 (depends on 8)

The method of claim 8 further including the step of communicating the generated fault condition to a controller.

### Claim 10 (depends on 8)

The method of claim 8 wherein the step of creating a variable reference voltage includes creating an initial reference voltage made up of the sum of the final reference voltage, that is set less than a final value of the device voltage, and a difference voltage, that sets an initial acceptable voltage over the final reference voltage.

### Claim 11

A system for detecting fault conditions in a semiconductor device having a gate signal and voltage source and being in communication with a controller, the system comprising:
a variable voltage reference generator;
a means for comparing a voltage from the device to the variable reference voltage;
a time delay means for time delaying the gate signal;
an AND gate for receiving a signal from the means for comparing and the time delay means; and
a controller for receiving the output from the AND gate and reporting a fault condition based upon the output.

### Claim 12 (depends on 11)

The system of claim 11 wherein the variable voltage reference generator includes means for creating an exponentially decaying reference voltage.