Microprocessor
a
Supervisory Circuits
ADM691A/ADM693A/ADM800L/M
FUNCTIONAL BLOCK DIAGRAM
FEATURES
Low Power Consumption:
Precision Voltage Monitor
BATT ON
؎2% Tolerance on ADM800L/M
Reset Time Delay—200 ms, or Adjustable
1 A Standby Current
1
4.65V
LOW LINE
V
CC
Automatic Battery Backup Power Switching
Fast Onboard Gating of Chip Enable Signals
Also Available in TSSOP Package (ADM691A)
V
OUT
V
BATT
CHIP ENABLE
OUTPUT
CONTROL
APPLICATIONS
Microprocessor Systems
Computers
CE
OUT
CE
IN
Controllers
Intelligent Instruments
Automotive Systems
Critical P Power Monitoring
RESET &
WATCHDOG
TIMEBASE
OSC IN
RESET &
GENERATOR
RESET
OSC SEL
RESET
WATCHDOG
WATCHDOG
TRANSITION DETECTOR
WATCHDOG
TIMER
WATCHDOG
INPUT (WDI)
OUTPUT (WDO)
POWER FAIL
INPUT (PFI)
GENERAL DESCRIPTION
POWER FAIL
1.25V
OUTPUT (PFO)
The ADM691A/ADM693A/ADM800L/ADM800M family of
supervisory circuits offers complete single chip solutions for
power supply monitoring and battery control functions in
microprocessor systems. These functions include µP reset,
backup-battery switchover, watchdog timer, CMOS RAM write
protection, and power-failure warning. The family of products
provides an upgrade for the MAX691A/93A/800M family of
products.
ADM691A/ADM693A
ADM800L/ADM800M
1
VOLTAGE DETECTOR = 4.4V (ADM693A/ADM800M)
INPUT
POWER
+5V
All parts are available in 16-pin DIP and SO packages. The
ADM691A is also available in a space-saving TSSOP package.
The following functionality is provided:
7805
0.1µF
V
CC
CMOS
RAM
V
V
BAT
ON
OUT
1. Power-on reset output during power-up, power-down and
brownout conditions. The circuitry remains operational with
CC
V
BATT
ADDRESS
DECODE
CE
BATTERY
OUT
R1
R2
CE
ADM691A
ADM693A
ADM800L
ADM800M
IN
V
CC as low as 1 V.
A0–A15
µP
POWER
PFI
GND
2. Battery backup switching for CMOS RAM, CMOS micro-
processor or other low power logic.
WDI
PFO
I/O LINE
NMI
OSC IN
µP
NC
RESET
RESET
OSC SEL
3. A reset pulse if the optional watchdog timer has not been
toggled within a specified time.
WDO
LOW LINE
4. A 1.25 V threshold detector for power fail warning, low bat-
tery detection, or to monitor a power supply other than +5 V.
SYSTEM
STATUS
INDICATORS
Figure 1. Typical Application
REV. 0
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700
Fax: 617/326-8703
World Wide Web Site: http://www.analog.com
© Analog Devices, Inc., 1996