# US 2014/0192449 A1 · Short-circuit protection circuit

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- Number: US 2014/0192449 A1
- Document ID: US20140192449A1
- Status: Published application
- Kind: A1
- Application number: 14/126,308
- Filed: 2012-07-10
- Published: 2014-07-10
- Earliest claimed: 2011-07-14
- Assignees: Fuji Electric Co., Ltd.
- Inventors: Naoki Shimizu
- Web page: https://patentgrep.com/patent/US20140192449A1

## CPC

- H03K 17/08112: {in bipolar transistor switches (H03K17/0812, H03K17/0814 take precedence)}
- H02M 1/08: Circuits specially adapted for the generation of control voltages for semiconductor devices incorporated in static converters
- H02M 1/36: Means for starting or stopping converters
- H03K 17/0828: {in composite switches}
- H03K: PULSE TECHNIQUE (measuring pulse characteristics G01R; modulating sinusoidal oscillations with pulses H03C; transmission of digital information H04L; discriminator circuits detecting phase difference between two signals by counting or integrating cycles of oscillation H03D3/04; automatic control, starting, synchronisation or stabilisation of generators of electronic oscillations or pulses where the type of generator is irrelevant or unspecified H03L; coding, decoding or code conversion, in general H03M)
- H02M: APPARATUS FOR CONVERSION BETWEEN AC AND AC, BETWEEN AC AND DC, OR BETWEEN DC AND DC, AND FOR USE WITH MAINS OR SIMILAR POWER SUPPLY SYSTEMS; CONVERSION OF DC OR AC INPUT POWER INTO SURGE OUTPUT POWER; CONTROL OR REGULATION THEREOF (transformers H01F; dynamo-electric converters H02K47/00; controlling transformers, reactors or choke coils, control or regulation of electric motors, generators or dynamo-electric converters H02P)

## Abstract

Provided is a short-circuit protection circuit having a mask circuit which can reduce a turn-on loss of a voltage-driven type semiconductor device during turn-on operation of the voltage-driven type semiconductor device. A mask circuit (21) is provided to suspend operation of an NLU circuit (24) during turn-on operation of a voltage-driven semiconductor device (1). Accordingly, the voltage-driven type semiconductor device (1) can be driven sufficiently so that a turn-on loss can be reduced.

## Claims

### Claim 1

A short-circuit protection circuit for protecting a voltage-driven semiconductor device from short-circuit breakdown, comprising:
a control circuit for generating a control voltage that is applied to a gate of the voltage-driven semiconductor device
an NLU (Non-Latch-Up) circuit which changes the control voltage in order to prevent the voltage-driven semiconductor device from latching-up due to a current flowing into the voltage-driven semiconductor device; and
a mask circuit which sets the NLU circuit at a non-operating state when the current flowing into the voltage-driven semiconductor device is at a level to operate the NLU circuit during a turn-on operation of the voltage-driven semiconductor device but a gate voltage of the voltage-driven semiconductor device is lower than a first reference voltage.

### Claim 2 (depends on 1)

The short-circuit protection circuit according to claim 1, wherein the mask circuit comprises:
a current detection resistor that is series-connected to a current detection terminal of the voltage-driven semiconductor device;
a first comparison portion whose output turns to an L level when the gate voltage applied to the gate of the voltage-driven semiconductor device is lower than the first reference voltage;
a second comparison portion whose output turns to an H level when a sense voltage on a high potential side of the current detection resistor is not lower than a second reference voltage; and
an AND circuit which takes a logical product of the output of the first comparison portion and the output of the second comparison portion.

### Claim 3 (depends on 2)

The short-circuit protection circuit according to claim 2, wherein:
the first reference voltage is set to be higher than a gate threshold voltage of the voltage-driven semiconductor device;
the second reference voltage is set at a level in which a voltage generated across the current detection sense resistor is indicative of a short-circuiting of the voltage-controlled semiconductor device; and
the mask circuit performs a mask operation where the gate voltage applied to the gate of the voltage-controlled semiconductor device is lower than the first reference voltage so as to set the NLU circuit at a non-operating state.

### Claim 4 (depends on 1)

The short-circuit protection circuit according to claim 1, wherein the voltage-driven semiconductor device is an insulated gate bipolar transistor.