Semiconductor device protection circuit
First Claim
1. A semiconductor device protection circuit comprising:
- semiconductor device for receiving at least one device control signal at a control electrode and, in response thereto, selectively passing current through the device between a pair of output electrodes of the device;
temperature sense means coupled to said device for developing a temperature sense signal having a magnitude indicative of the temperature of said device; and
control means coupled to said temperature sense means for receiving said temperature sense signal and an external control signal and selectively determining said device control signal in accordance therewith;
wherein the improvement comprises said control means including means for protecting said device by increasing on conduction of said device in response to said temperature sense signal indicating the temperature of the device exceeds a first high temperature threshold close to the maximum rated junction temperature of said device.
1 Assignment
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Accused Products
Abstract
FET protection circuit (10; 100) senses the temperature of a FET (11) and, via a control circuit (24), increases FET conduction in response to sensed FET temperature exceeding a high temperature threshold (160° C.) close to the maximum rated junction temperature (175° C.) of the FET. This allows the FET to survive excessive drain-to-source voltages which occur during load dump conditions even when load dump is sensed by a zener diode (26) which initially turns on the FET. During load dump after a zener diode (26) turns on the FET, in response to sensing excessive FET temperature the FET is turned in harder so as to reduce the drain-to-source voltage (VDS) and minimize power dissipation during load dump thereby protecting the FET. Normal overcurrent and maximum temperture turn off circuitry (44, 33, 60-63) is effectively overridden by high temperature threshold turn-on circuitry (50). Preferably, a majority of the control circuit (24) is provided on an integrated circuit, but an external resistor (31) allows effective adjustment of two temperature thresholds (150° C., 160° C.) above which control signals provided to the FET will be modified.
62 Citations
30 Claims
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1. A semiconductor device protection circuit comprising:
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semiconductor device for receiving at least one device control signal at a control electrode and, in response thereto, selectively passing current through the device between a pair of output electrodes of the device; temperature sense means coupled to said device for developing a temperature sense signal having a magnitude indicative of the temperature of said device; and control means coupled to said temperature sense means for receiving said temperature sense signal and an external control signal and selectively determining said device control signal in accordance therewith; wherein the improvement comprises said control means including means for protecting said device by increasing on conduction of said device in response to said temperature sense signal indicating the temperature of the device exceeds a first high temperature threshold close to the maximum rated junction temperature of said device. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A semiconductor device protection circuit comprising:
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semiconductor device for receiving at least one device control signal at a control electrode and, in response thereto, selectively passing current through the device between a pair of output electrodes of the device; temperature sense means coupled to said device for developing a temperature sense signal having a magnitude indicative of the temperature of said device; and control means coupled to said temperature sense means for receiving said temperature sense signal and an external control signal and selectively determining said device control signal in accordance therewith; wherein the improvement comprises said control means including load dump means for sensing a load dump condition and turning said device on in response thereto and additional means for determining said control signal such that said device is on in response to said sensed device temperature exceeding a first predetermined high temperature threshold. - View Dependent Claims (9, 10, 11, 12)
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13. A semiconductor device protection circuit comprising:
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semiconductor device for receiving at least one device control signal at a control electrode and, in response thereto, selectively passing current through the device between a pair of output electrodes of the device; temperature sense means coupled to said device for developing a temperature sense signal having a magnitude indicative of the temperature of said device; and control means coupled to said temperature sense means for receiving said temperature sense signal and an external control signal and selectively determining said device control signal in accordance therewith; wherein the improvement comprises said control means including load dump means for sensing the occurrence of load dump and turning said device on in response thereto and means for turning said device on harder, thus decreasing power dissipation in said device, during load dump and in response to the sensed temperature of said device exceeding a first predetermined high temperature threshold. - View Dependent Claims (14, 15, 16, 17, 18)
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19. A semiconductor device protection circuit comprising:
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semiconductor device for receiving at least one device control signal at a control electrode and, in response thereto, selectively passing current through the device between a pair of output electrodes of the device; temperature sense means coupled to said device for developing a temperature sense signal having a magnitude indicative of the temperature of said device; control means coupled to said temperature sense means for receiving said temperature sense signal and an external control signal and selectively determining said device control signal in accordance therewith; means for sensing said current passing through said semiconductor device and providing a current sense electrical signal having a magnitude indicative thereof; and said control means including means for turning said device off by modifying said device control signal in response to said current through said device exceeding a maximum overcurrent limit; wherein the improvement comprises said control means including means for turning said device on in response to the temperature of said device exceeding a first predetermined high temperature threshold despite the current through said device exceeding said maximum overcurrent limit. - View Dependent Claims (20, 21, 22)
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23. A semiconductor device protection circuit comprising:
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semiconductor device for receiving at least one device control signal at a control electrode and, in response thereto, selectively passing current through the device between a pair of output electrodes of the device; temperature sense means coupled to said device for developing a temperature sense signal having a magnitude indicative of the temperature of said device; and control means coupled to said temperature sense means for receiving said temperature sense signal and selectively modifying said device control signal in response to said sensed device temperature exceeding a temperature threshold; wherein the improvement comprises a majority of said control means being provided on a control integrated circuit and means, external to said integrated circuit, for allowing external adjustment of the device temperature at which said control means will modify said device control signal which controls said device through current. - View Dependent Claims (24, 25, 26)
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27. A semiconductor device protection circuit comprising:
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semiconductor device for receiving at least one device control signal at a control electrode and, in response thereto, selectively passing current through the device between a pair of output electrodes of the device; temperature sense means coupled to said device for developing a temperature sense signal having a magnitude indicative of the temperature of said device; and control means coupled to said temperature sense means for receiving said temperature sense signal and selectively modifying said device control signal in response to said sensed device temperature exceeding a temperature threshold; wherein the improvement comprises a majority of said control means being provided on a control integrated circuit and means, external to said integrated circuit, for allowing external adjustment of the device temperature at which said control means will modify said device control signal, and wherein said control means increases on conduction of said device in response to the temperature of said device exceeding said threshold.
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28. A semiconductor device protection circuit comprising:
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semiconductor device for receiving at least one device control signal at a control electrode and, in response thereto, selectively passing current through the device between a pair of output electrodes of the device; temperature sense means coupled to said device for developing a temperature sense signal having a magnitude indicative of the temperature of said device; and control means coupled to said temperature sense means for receiving said temperature sense signal and selectively modifying said device control signal in response to said sensed device temperature exceeding a temperature threshold; wherein the improvement comprises a majority of said control means being provided on a control integrated circuit and means, external to said integrated circuit, for allowing external adjustment of the device temperature at which said control means will modify said device control signal, and wherein said control means turns said device off in response to the temperature of said device exceeding said threshold.
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29. A semiconductor device protection circuit comprising:
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semiconductor device for receiving at least one device control signal at a control electrode and, in response thereto, selectively passing current through the device between a pair of output electrodes of the device; temperature sense means coupled to said device for developing a temperature sense signal having a magnitude indicative of the temperature of said device; and control means coupled to said temperature sense means for receiving said temperature sense signal and selectively modifying said device control signal in response to said sensed device temperature exceeding a temperature threshold; wherein the improvement comprises a majority of said control means being provided on a control integrated circuit and means, external to said integrated circuit, for allowing external adjustment of the device temperature at which said control means will modify said device control signal, and wherein said control means utilizes said temperature sense signal magnitude to increase on conduction of said device in response to the temperature of said device exceeding a first temperature threshold and to turn said device off in response to the temperature of said device exceeding a second temperature threshold, lower than said first temperature threshold, said external adjustment means determining said temperature sense signal magnitude. - View Dependent Claims (30)
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Specification