An integrated circuit composite PNPN diode

A composite PNPN diode has been successfully incorporated into an integrated circuit chip. The device is used in parallel with an integrated circuit to serve as a surge protector for certain pulse conditions. The composite PNPN clamps forward polarity voltages to low values as long as the fault source current is above a threshold current. At lower currents, the PNPN recovers from saturation, and the integrated circuit returns to normal operation. The design of the PNPN is such that the pulse current handling capability of the device is at least 4 A at an operating temperature of 25°C, and the hold current is greater than 100 mA over a temperature range of 0° to 90°C. A special diode was merged with the structure to provide a controlled breakover voltage of 9 V. The typical device is capable of taking a 5 A pulse of 1 ms width without failing. It can also handle a current pulse of greater than 6 A when the pulse is less than 50 µs.