Microprocessor Supervisory

SGM803/SGM809/SGM810

Circuit in 3-Pin SOT-23

8

JANUARY 2018

SG Micro Corp

www.sg-micro.com

APPLICATION INFORMATION

Benefits of an 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 SGM803/SGM809/

SGM810 series can operate effectively even when

there are large degradations of the supply voltages.

Another advantage of the SGM803/SGM809/SGM810

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 (for example, thermal,

altitude, and velocity sensors). The SGM803/SGM809/

SGM810 can easily be integrated into existing interrupt-

handling circuits, as shown in Figure 1, or can be used

as a standalone device.

SGM809

GND

RESET

OTHER SENSING

DEVICES

PRIORITY ENCODER

74LS147

4-LINE BCD TO

MICROPROCESSOR

Figure 1. Interfacing to Microprocessors with Multiple

Interrupts

Interfacing to Other Devices’ Output

The SGM803/SGM809/SGM810 series is designed to

integrate with as many devices as possible and,

This enables the parts to be used in both 3V and 5V, or

any nominal voltage within the minimum and maximum

this device to other devices.

= 0V

RESET

no longer sinks current. A high impedance

drift to undetermined logic levels. To eliminate this

problem, a 100kΩ resistor should be connected from

SGM809

GND

RESET

Preventing the High Voltage Spike and

Low Power Design

current limitation low power design, It is always to

such application, one capacitance C1(0.1µF to 4.7µF)

schematic is shown in Figure 3. The input resistor will

affect output driving capability.

SGM809

GND

RESET

OUTPUT

IN

R1

0Ω ~ 1kΩ

C1

0.1µF ~ 4.7µF

Figure 3. Preventing the High Voltage Spike and Low

Power Design