LOAD DRIVE APPARATUS
First Claim
1. A load drive apparatus comprising a switching element connected in series to a DC power source and an electric load,a drive circuit for generating control signals to turn said switching element on and off,a thermal detection element for detecting a temperature of the switching element,an overheat protective circuit for generating an overheat detection signal when the thermal detection element detects the temperature of the switching element over a predetermined temperature level, anda disconnection detection circuit having a current mirror circuit connected to one and the other terminals in the thermal detection element to detect disconnection in wiring between the thermal detection element and overheat protective circuit by the current mirror circuit,wherein the overheat protective circuit or disconnection detection circuit produces an output signal to block transmission of control signals from the control circuit to the switching element when the overheat protective circuit produces the overheat detection signal or when the disconnection detection circuit detects the disconnection in wiring between the thermal detection element and overheat protective circuit.
1 Assignment
0 Petitions
Accused Products
Abstract
A load drive apparatus is provided which comprises a switching element 3 connected in series to a DC power source Vccand an electric load 4, a drive circuit 5 for generating control signals to turn switching element 3 on and off, a thermal detection element 6 for sensing a temperature of switching element 3, an overheat protective circuit 7 for generating an overheat detection signal when thermal detection element 6 senses the temperature of switching element 3 over a predetermined temperature level, and a disconnection detection circuit 11 provided with a current mirror circuit 12 connected between one and the other terminals of thermal detection element 6 for detecting a disconnection in wiring between thermal detection element 6 and overheat protective circuit 7. When overheat protective circuit 7 produces an overheat detection signal or when disconnection detection circuit 11 detects a breaking of wiring between thermal detection element 6 and overheat protective circuit 7, the control signal from drive circuit 5 is prohibited to be given to switching element 3. In case of disconnection in wiring between the thirmal detection element 6 and overheat protective circuit 7, the load drive apparatus can prevent thermal damage to the switching element used therein.
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Citations
6 Claims
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1. A load drive apparatus comprising a switching element connected in series to a DC power source and an electric load,
a drive circuit for generating control signals to turn said switching element on and off, a thermal detection element for detecting a temperature of the switching element, an overheat protective circuit for generating an overheat detection signal when the thermal detection element detects the temperature of the switching element over a predetermined temperature level, and a disconnection detection circuit having a current mirror circuit connected to one and the other terminals in the thermal detection element to detect disconnection in wiring between the thermal detection element and overheat protective circuit by the current mirror circuit, wherein the overheat protective circuit or disconnection detection circuit produces an output signal to block transmission of control signals from the control circuit to the switching element when the overheat protective circuit produces the overheat detection signal or when the disconnection detection circuit detects the disconnection in wiring between the thermal detection element and overheat protective circuit.
Specification