Supervisory Circuits Eliminate External Components

Unterpremstaetten, Austria — austriamicrosystems AG launched the AS1904/5/6 family of ultra low power supervisory circuits. With a current consumption of 150 nA (typical) at 3.3 V, the devices are intended for use in portable/battery-powered equipment, computers, controllers, critical microprocessor and microcontroller power monitoring, intelligent instruments and automotive applications.

The AS1904/5/6 family delivers low power consumption and reduces costs by eliminating all external components such as capacitors and resistors. These devices monitor the supply voltage of digital systems and microprocessors and initiate a reset if the voltage decreases below a certain threshold. The state of the reset is active for a predefined time after the supply voltage has risen above the threshold.

The product family offers three devices with different output drivers. The AS1904 has a push-pull driver with an active low reset. The AS1905 uses the same output stage, but has an active high reset. The AS1906 has an open drain output with an active low reset. Each device is offered with four typical time out periods: 5 milliseconds, 20 ms, 100 ms and 500 ms (factory trimmed).

All devices of the AS1904/5/6 family operate down to a voltage of 1 V. “A hysteresis in the threshold guarantees that fast transients and noise on the supply line do not lead to unwanted resets,” said Walter Moshammer, marketing director of austriamicrosystems' communications business unit. Furthermore, the reset threshold is factory-trimmable between 2.2 V and 3.1 V with 1.5% tolerance. The circuit is designed to be especially robust against RF-interference,” he added.

The AS1904/5/6 family of devices is available immediately in 3-pin SOT23 packaging. In 1,000-piece quantities, pricing is less than $1.

Data sheet for the AS1904.

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