SP691A Datasheet, PDF (10/24 Pages) Sipex Corporation – Low Power Microprocessor Supervisory with Battery Switch-Over

Unregulated DC
R1
Regulated +5V
PFI
R2
VCC
VCC
µP ^RESET
NMI
RESET
PFO
A0-A15 ^{I/O LINE}
WDI
Backup VBATT
Supply
Address
BUS
Decode
BATT ON
CMOS
RAM1
to
VCC
RAMn
0.1µF
CEIN
VOUT
CEOUT
GND
WDO
alarm
LOWLINE
system
status
indicator
Figure 17. Typical Application Circuit of the SP691A/693A/800L/800M
FEATURES
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.
THEORY OF OPERATION
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
VCC down to 1V, even with no battery in
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.
Date: 5/25/04
SP691A/693A/800L/800M Low Power Microprocessor Supervisor with Battery Switch-Over © Copyright 2004 Sipex Corporation
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