REV. C

ADM803/ADM809/ADM810

–7–

ADM8_L/M/J

400

350

0

110

1000

100

300

250

50

200

150

100

ADM8_R/S/T/Z

TPC 7. Maximum Transient Duration without Causing a

Reset Pulse vs. Reset Comparator Overdrive

INTERFACING TO OTHER DEVICES’ OUTPUT

The ADM803/ADM809/ADM810 series is designed to integrate

with as many devices as possible and, therefore, has a standard

both 3 V and 5 V or any nominal voltage within the minimum

approach, interfacing this device to other devices is simplified.

no longer 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 3. Ensuring a Valid Reset Output Down

Benefits of a Very Accurate Reset Threshold

In other microprocessor supervisory circuits, tolerances in supply

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 ADM803/ADM809/ADM810 series

can operate effectively even when there are large degradations

of the supply voltages. Another advantage of the ADM803/

ADM809/ADM810 series is its very accurate internal voltage

reference circuit. These benefits combine to produce an excep-

tionally 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 (e.g., thermal, altitude, and velocity sensors).

The ADM803/ADM809/ADM810 can easily be integrated into

existing interrupt-handling circuits (Figure 4) or be used as a

standalone device.

PRIORITY ENCODER

74LS147

4-LINE BCD TO

MICROPROCESSOR

ADM809

GND

RESET

OTHER SENSING

DEVICES

Figure 4. Interfacing to Microprocessors with

Multiple Interrupts