ADM809/ADM810

–5–

REV. 0

The ADM809/ADM810 Series is designed to integrate with as

many devices as possible and therefore has a standard output

and 5 V or any nominal voltage within the minimum and maxi-

interfacing this device to other devices is simplified.

sinks current. A high impedance CMOS logic input connected

to RESET may, therefore, drift to undetermined logic levels. To

eliminate this problem a 100 k

Ω resistor should be connected

from RESET to ground.

GND

RESET

ADM809

Figure 10. Ensuring a Valid RESET Output Down to

THE BENEFITS OF A VERY ACCURATE RESET

THRESHOLD

In other microprocessor supervisory circuits, tolerances in sup-

ply voltages lead to an overall increase in RESET tolerance

levels due to the deterioration of the microprocessor RESET

circuit’s power supply. The possibility of a malfunction during

a power failure is greatly reduced because the ADM809 and

ADM810 series can operate effectively even when there are

large degradations of the supply voltages. Another advantage of

the ADM809 and ADM810 series is its very accurate internal

voltage reference circuit. These benefits combine to produce an

exceptionally reliable Voltage Monitor Circuit.

INTERFACING TO MICROPROCESSORS WITH

MULTIPLE INTERRUPTS

In a number of cases it is necessary to interface many interrupts

from different devices (i.e., thermal, attitude and velocity sen-

sors). The ADM809 and ADM810 can easily be integrated into

existing interrupt-handling circuits (Figure 11) or used as a

stand-alone device.

PRIORITY ENCODER

74LS147

4 LINE BCD

TO

µP

ADM809

GND

RESET

OTHER SENSING

DEVICES

Figure 11. Interfacing to

µPs with Multiple Interrupts