Date: 4/18/05

SP691A/693A/800L/800M Low Power Microprocessor Supervisor with Battery Switch-Over © Copyright 2005 Sipex Corporation

10

The SP691A/693A/800L/800M devices are

microprocessor (

µP) supervisory circuits that

monitor the power supplied to digital circuits

such as microprocessors, microcontrollers, or

memory. The SP691A/693A/800L/800M series

is an ideal solution for portable, battery-

powered equipment that require power supply

monitoring. The SP691A/693A/800L/800M

watchdog functions will continuously oversee

the operational status of a system. Implementing

the SP691A/693A/800L/800M series will

reduce the number of components and overall

complexity in a design that requires power

supply monitoring circuitry. The operational

features and benefits of this series are described

in more detail below.

Figure 17. Typical Application Circuit of the SP691A/693A/800L/800M

RESET

NMI

I/O LINE

RESET

PFO

WDI

GND

Unregulated DC

Regulated +5V

PFI

µP

CMOS

to

BATT ON

Address

Decode

BUS

Backup

Supply

A0-A15

0.1µF

alarm

system

status

indicator

WDO

LOWLINE

The SP691A/693A/800L/800M series is a

complete

µP supervisor IC and provides the

following main functions:

1)

µP reset ➡ Reset output is asserted during

power fluxiations such as power-up,

power-down, and brown out conditions, and

is guaranteed to be in the correct state for

the circuit.

2)

µP reset ➡ Reset output is pulsed if the

optional watchdog timer has not been

toggled within a specified time.

3) Power Fail Comparator ➡ Provides for

power-fail warning and low-battery

detection, or monitors another power

supply.

FEATURES

THEORY OF OPERATION