feature

Specified over temperature; low power: 17 μA; precision voltage monitor: 2.5 V, 3 V, 3.3 V, 5 V options; reset assertion to 1 V VCC; 140 ms minimum power-on reset; open-drain reset output (push Pull-Reset Output ( ADM803 Model ADM809; Push-Pull Reset Output (ADM810); SC70 and SOT-23 Packages.

application

Microprocessor systems; computers; controllers; intelligent instruments.

General Instructions

The ADM803/ADM809/ADM810 supervisory circuits are used to monitor supply voltages in microprocessor systems. They provide reset outputs in power-up, power-down, and power-down states. On power-up, an internal timer holds the asserted reset for 240 ms. This will keep the microprocessor in reset until conditions stabilize. The reset output remains operating down to 1V. The ADM803 and ADM809 provide an active low reset signal (reset), while the ADM810 provides an active high signal (reset) output. The ADM809 and ADM810 have push-pull outputs, while the ADM803 has open-drain outputs, which require external pull-up resistors.

There are seven reset threshold voltage options for monitoring various supply voltages.

The reset comparator has built-in fault immunity, making it immune to fast transients on V.

The ADM803/ADM809/ADM810 consume only 17μA, making them suitable for low-power portable devices. The ADM803 is available in the 3-wire SC70; the ADM809/ADM810 are available in the 3-wire SOT-23 and 3-wire SC70 software packages.

Pin Configuration and Functional Description

Typical performance characteristics

Interface with other devices

The ADM803/ADM809/ADM810 family is designed to integrate as much as possible with the device and therefore has a V-dependent standard output. This enables the part to be used in 3 V and 5 V, or any nominal voltage range with a minimum and maximum specification of V. This design simplifies the interface to other devices.

Ensure a valid reset output VCC = 0 volts

When VCC is below 0.8 V, the ADM803/ADM809 resets no longer sink current. High impedance CMOS logic input, therefore, connected to reset may drift to an indeterminate logic level. To eliminate this problem, a 100 kΩ resistor should be ground from reset.

Benefits of Precisely Resetting Thresholds

In other microprocessors, the tolerance of the supply voltage leads to an overall increase in the reset tolerance level due to the deterioration of the power supply of the reset circuit. In the ADM803/ADM809/ADM810, the probability of failure during a power failure is greatly reduced because the device operates efficiently even when the supply voltage is greatly reduced. Another advantage is the very accurate internal voltage reference circuitry of the ADM803/ADM809/ADM810. These advantages combine to produce a very reliable voltage monitoring circuit.

Multi-Interrupt Microprocessor Interface

In many cases, multiple interrupts from different devices (eg, temperature, altitude, and speed sensors) must be connected. The ADM803/ADM809/ADM810 can be easily integrated into existing interrupt handling circuits, as shown in Figure 13, or can be used as stand-alone devices.