Importance

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Abstract

A current sense circuit (100) includes a semiconductor power switch such as a MOSFET (102) having a source metallization contact pad (14) with a conductor jumper bond wire (106) directly connected thereto in the MOSFET module housing (104), which bond wire is connected to a source terminal lead frame within the module, which lead frame extends externally of the module for connection to a load (22) and load voltage (24). The current sense circuitry includes amplifier circuitry (150, 168) having first and second inputs (122, 124) connected to the source bond wire (106) at spaced points (126, 128) along the bond wire within the module housing (104) without insertion of additional series shunt resistance in the bond wire (106) between such points (126, 128), and sensing current flow through the bond wire (106) by sensing voltage between such points (126, 128) and amplifying such voltage. A comparator (218) compares the amplified voltage against a reference voltage (226) and generates an output signal ( 232) when the amplified voltage exceeds the reference voltage by a given amount. The output signal disables gate drive to the MOSFET. The speed of the gate drive signal is improved by providing a separate gate return jumper bond wire to the MOSFET source. Another comparator (242) compares thermistor (238) voltage, measuring MOSFET temperature, against a reference voltage (246) and generates an output signal (260) which disables gate drive to the MOSFET when the latter's temperature exceeds a given level, to provide overtemperature protection in combination with overcurrent protection.

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First Claim