Current sense circuit

Details Current sense circuit Current sense circuit

1988-09-29

1990-07-31

Shoop, Jr., William M.

Electricity: electrical systems and devices

Safety and protection of systems and devices

With specific current responsive fault sensor

361 94, 361 87, 324123C, 324126, 323277, 323280, 307356, 307521, H02H 308

Patent

active

049454455

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.

REFERENCES:
patent: 3832646 (1974-08-01), Szabo
patent: 4032766 (1977-06-01), Hughes et al.
patent: 4157513 (1979-06-01), Ghiringhelli et al.
patent: 4337494 (1982-06-01), Huykman
patent: 4369354 (1983-01-01), Goedecke et al.
patent: 4623950 (1986-11-01), Palara et al.
patent: 4659997 (1987-04-01), Ferland et al.
patent: 4703390 (1987-10-01), Fay et al.
patent: 4713607 (1987-12-01), Pepper
patent: 4819117 (1989-04-01), Brennan et al.
"Current Sensing HEXSense Power MOSFETS Simplify SMPS Design and Lower Losses", Sean Young, PCIM (Power Conversion and Intelligent Motion Magazine), Jul. 1987, pp. 76-83.

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