The AS1904/5/6 family of ultralow-power supervisory circuits from austriamicrosystems, Raleigh, N.C., consume just 150 nA and targets portable/batterypowered equipment, computers, controllers, microprocessor/microcontroller power monitoring, intelligent instruments, and automotive applications. The circuits monitor supply voltage and initiate a reset when voltage dips below a certain threshold. The reset state remains active for a predefined time after supply voltage exceeds the threshold.

Models are available with three different output drivers: AS1904s use a push-pull driver with an active low reset; AS1905s use the same output stage but have an active high reset; and AS1906s have an open-drain output with an active low reset. All models come with time-out periods of 5, 20, 100, and 500 msec (factory trimmed) and operate down to 1 Vdc. Reset threshold is factorytrimmable between 2.2 and 3.1 Vdc ±1.5%. A low level of threshold-voltage hysteresis stops fast transients and supply-line noise such as RF interference from triggering unwanted resets. The AS1904/5/6 family comes in a three-pin SOT23 package.