Switchable Power Supply to Prevent Latchup Damage to CMOS Integrated Circuits
Original Publication Date: 1985-Feb-01
Included in the Prior Art Database: 2005-Feb-18
Latchup in CMOS causes a momentary dip in the power supply voltage and a surge of current flowing into a chip due to the low impedance characteristic of the latched device. Sensing the voltage dip or current surge and removing the power from the chip when such an event is detected prevents damage to the circuitry caused by excessive current flow. Power can be reapplied after a delay-time sufficient enough for the nodes in the circuit to discharge to a level below the sustaining voltage for the latched device. In order to prevent circuit damage, a switch/detector 11 is placed at a point between the power supply and a circuit board 12, and individual chip 13 or a block of circuits 14 on the chip (Fig. 1). For the circuit board 12, the switch/detector 11 could be a separate chip.