# US 2020/0403397 A1 · Switching controller with adaptive overheating protection

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- Number: US 2020/0403397 A1
- Document ID: US20200403397A1
- Status: Published application
- Kind: A1
- Application number: 16/864,438
- Filed: 2020-05-01
- Published: 2020-12-24
- Earliest claimed: 2019-06-18
- Assignees: Fuji Electric Co., Ltd.
- Applicants: Fuji Electric Co., Ltd.
- Inventors: Sho NAKAGAWA; Morio IWAMIZU
- Web page: https://patentgrep.com/patent/US20200403397A1

## CPC

- G01K 3/005: {Circuits arrangements for indicating a predetermined temperature (fire detection G08B17/00)}
- H02H 3/087: for DC applications
- G01K 7/01: using semiconducting elements having PN junctions (G01K7/02, G01K7/16, G01K7/30 take precedence)
- G01R 19/16528: {using digital techniques or performing arithmetic operations (using digital techniques to measure a voltage or a current, see G01R19/25)}
- G05F 1/573: with overcurrent detector
- H02H 5/041: {additionally responsive to excess current (H02H5/048 takes precedence)}
- H03K 3/0377: {Bistables with hysteresis, e.g. Schmitt trigger (non-regenerative amplitude discriminators G01R19/165)}
- H03K 17/08122: {in field-effect transistor switches}
- H03K 19/00315: {in field-effect transistor circuits}
- H10D 8/25: Zener diodes
- H02H 3/006: {Calibration or setting of parameters}
- H02H 9/025: {Current limitation using field effect transistors}
- H03K 2017/0806: {against excessive temperature}
- G01K: MEASURING TEMPERATURE; MEASURING QUANTITY OF HEAT; THERMALLY-SENSITIVE ELEMENTS NOT OTHERWISE PROVIDED FOR (radiation pyrometry G01J5/00)
- H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H)
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- G05F: SYSTEMS FOR REGULATING ELECTRIC OR MAGNETIC VARIABLES
- 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)
- H10D: INORGANIC ELECTRIC SEMICONDUCTOR DEVICES

## Abstract

A semiconductor device includes a power semiconductor switch; a logic circuit connected to an input terminal; an overheat detection circuit that outputs to the logic circuit an overheat detection signal when a temperature of the power semiconductor switch exceeds an overheat detection threshold; and an overcurrent detection circuit that monitors a current that flows through the power semiconductor switch and that outputs to the logic circuit and to the overheat detection circuit an overcurrent detection signal when the current that flows through the power semiconductor switch exceeds a prescribed threshold, wherein in the overheat detection circuit, the overheat detection threshold values is changed from a first threshold value to a second threshold value that is lower than the first threshold value when the overheat detection circuit receives the overcurrent detection signal from the overcurrent detection circuit.

## Claims

### Claim 1

A semiconductor device having an input terminal to receive an input signal, an output terminal to be connected to a load, and a power supply terminal to receive a power supply voltage, the semiconductor device comprising:
a power semiconductor switch connected between the power supply terminal and the output terminal;
a logic circuit connected to the input terminal, the logic circuit generating a logic output signal in accordance with the input signal inputted to the input terminal, the logic output signal causing the power semiconductor switch to turn ON or OFF;
an overheat detection circuit that outputs to the logic circuit an overheat detection signal when a temperature of the power semiconductor switch exceeds an overheat detection threshold; and
an overcurrent detection circuit that monitors a current that flows through the power semiconductor switch and that outputs to the logic circuit and to the overheat detection circuit an overcurrent detection signal when the current that flows through the power semiconductor switch exceeds a prescribed threshold,
wherein in the overheat detection circuit, the overheat detection threshold is set to a first threshold value when semiconductor device is operating normally, and the overheat detection threshold values is changed to a second threshold value that is lower than the first threshold value when the overheat detection circuit receives the overcurrent detection signal from the overcurrent detection circuit.

### Claim 2 (depends on 1)

The semiconductor device according to claim 1, wherein when the logic circuit receives the overcurrent detection signal, the logic circuit generates and outputs a chopping signal, as the logic output signal, that causes the power semiconductor switch to operate in a chopping mode.

### Claim 3 (depends on 1)

The semiconductor device according to claim 1, wherein the overheat detection circuit includes a temperature detection sensor comprising a plurality of diodes mutually connected in series, and a switching device that short-circuits one or more of the plurality of diodes in response to the overcurrent detection signal.

### Claim 4 (depends on 1)

The semiconductor device according to claim 1, further comprising:
a high-voltage detection circuit that monitors the power supply voltage on the power supply terminal and outputs to the overheat detection circuit a high-voltage detection signal when the power supply voltage exceeds a prescribed voltage,
wherein when the overheat detection circuit receives the high-voltage detection signal from the high-voltage detection circuit, the overheat detection threshold values is also changed from the first threshold value to the second threshold value.

### Claim 5 (depends on 4)

The semiconductor device according to claim 4, wherein the overheat detection circuit comprises:
a temperature detection sensor comprising a plurality of diodes mutually connected in series;
an OR gate configured to receive the overcurrent detection signal and the high-voltage detection signal; and
a switching device connected to an output of the OR gate, the switching device short-circuiting one or more of the plurality of diodes when the output of the OR gate is HIGH.

### Claim 6 (depends on 3)

The semiconductor device according to claim 3, further comprising:
a high-voltage detection circuit that monitors the power supply voltage on the power supply terminal and outputs to the overheat detection circuit a high-voltage detection signal when the power supply voltage exceeds a prescribed voltage,
wherein the switching device of the overheat detection circuit also short-circuits said one or more of the plurality of diodes in response to the high-voltage detection signal.

### Claim 7 (depends on 1)

The semiconductor device according to claim 1, wherein the overcurrent protection circuit includes an inverter circuit that monitors a voltage at the output terminal and that outputs the overcurrent detection signal when a voltage drop due to an ON resistance of the power semiconductor switch becomes lower than an output inversion threshold of the inverter circuit.

### Claim 8 (depends on 1)

The semiconductor device according to claim 1, further comprising:
a high-voltage detection circuit that monitors the power supply voltage on the power supply terminal and outputs to the overheat detection circuit a high-voltage detection signal when the power supply voltage exceeds a prescribed voltage,
wherein the overcurrent protection circuit includes an inverter circuit that monitors a voltage at the output terminal and that outputs the overcurrent detection signal when a voltage drop due to an ON resistance of the power semiconductor switch becomes lower than an output inversion threshold of the inverter circuit,
wherein the high-voltage detection circuit comprises:
a first constant current circuit, a second constant current circuit, and a plurality of Zener diodes, all of which are connected in series between the power supply terminal and a ground terminal;
a Zener diode for logic signal generation, connected in parallel to the first constant current circuit, the Zener diode for logic signal generation generating a logic signal with reference to the power supply voltage at the power supply voltage terminal; and
an inverter circuit that receives a voltage at a node connecting the first constant current circuit and the second constant current source and that outputs the high-voltage detection signal when the power supply voltage applied to the power supply voltage terminal exceeds a sum of respective Zener voltages of the plurality of Zener diodes and the Zener diode for logic signal generation, and
wherein the overheat detection circuit comprises:
a temperature detection sensor comprising a plurality of diodes mutually connected in series;
an OR gate configured to receive the overcurrent detection signal and the high-voltage detection signal; and
a switching device connected to an output of the OR gate, the switching device short-circuiting one or more of the plurality of diodes when the output of the OR gate is HIGH.

### Claim 9

A semiconductor device having an input terminal to receive an input signal, an output terminal to be connected to a load, and a power supply terminal to receive a power supply voltage, the semiconductor device comprising:
a power semiconductor switch connected between the power supply terminal and the output terminal;
a logic circuit connected to the input terminal, the logic circuit generating a logic output signal in accordance with the input signal inputted to the input terminal, the logic output signal causing the power semiconductor switch to turn ON or OFF;
an overheat detection circuit that outputs to the logic circuit an overheat detection signal when a temperature of the power semiconductor switch exceeds an overheat detection threshold; and
a high-voltage detection circuit that monitors the power supply voltage on the power supply terminal and outputs to the overheat detection circuit a high-voltage detection signal when the power supply voltage exceeds a prescribed voltage,
wherein in the overheat detection circuit, the overheat detection threshold is set to a first threshold value when semiconductor device is operating normally, and the overheat detection threshold values is changed to a second threshold value that is lower than the first threshold value when the overheat detection circuit receives the high-voltage detection signal from the high-voltage detection circuit.

### Claim 10 (depends on 9)

The semiconductor device according to claim 9, wherein the overheat detection circuit includes a temperature detection sensor comprising a plurality of diodes mutually connected in series, and a switching device that short-circuits one or more of the plurality of diodes in response to the high-voltage detection signal.

### Claim 11 (depends on 9)

The semiconductor device according to claim 9, wherein the high-voltage detection circuit comprises:
a first constant current circuit, a second constant current circuit, and a plurality of Zener diodes, all of which are connected in series between the power supply terminal and a ground terminal;
a Zener diode for logic signal generation, connected in parallel to the first constant current circuit, the Zener diode for logic signal generation generating a logic signal with reference to the power supply voltage at the power supply voltage terminal; and
an inverter circuit that receives a voltage at a node connecting the first constant current circuit and the second constant current source and that outputs the high-voltage detection signal when the power supply voltage applied to the power supply voltage terminal exceeds a sum of respective Zener voltages of the plurality of Zener diodes and the Zener diode for logic signal generation.