A nonvolatile eight-bit asynchronous counter and its applications

This paper is concerned with an interesting application of p-channel MNOS on silicon-on-sapphire (SOS) technology: a nonvolatile eight-bit asynchronous counter. This circuit has two count modes: binary and decimal (or BCD). It is fully TTL compatible and needs two power supplies: V/SUB CC/=+5 V/spl plusmn/5 percent and V/SUB DD/=-12 V to -35 V. Maximum count frequency is 1 MHz. Data storage necessitates two pulses, each being 100 ms long. Data retention is expected to be about five years, in the -55 to +125/spl deg/C temperature range. A nonvolatile time counter, which can be used to totalize operating time of a system or a particular device, up to 10000 h, is described as an example of application of such a circuit.