Importance

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Abstract

One or more probe cells are use to sense voltage and current accurately and without affecting performance of the switching device (T.sub.1) or the load. In addition, power, resistance, and temperature can be determined from the voltage and current. Voltage sensing is accomplished by placing a large value resistor (R.sub.3) (much greater than the on-resistance of the probe cell(s) between the probe cell(s) and its low voltage connection (the common source terminal in the case of MOSFET's). Since the resistor (R.sub.3) is much greater than the cell resistance, the voltage across the resistor is nearly equal to the voltage across the power chip (10). Current probe cells are isolated from switching cells (27) in MOSFET power chips. The cell locations adjacent the probe cells are occupied by cells (50) that are inactive by virtue of their not having had a source region implanted therein during the chip fabrication. This isolation prevents any crosstalk between probe and switching cells.

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First Claim