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FEATURES
Superior Upgrade for MAX696/MAX697
Specified Over Temperature
Adjustable Low Line Voltage Monitor
Power OK/Reset Time Delay
Reset Assertion Down to 1 V VCC
Watchdog Timer—100 ms, 1.6 s, or Adjustable
Low Switch On Resistance
1.5 ⍀ Normal, 20 ⍀ in Backup
600 nA Standby Current
Automatic Battery Backup Switching (ADM696)
Fast On-Board Gating of Chip Enable Signals (ADM697)
Voltage Monitor for Power Fail or Low Battery Warning
Microprocessor
Supervisory Circuits
ADM696/ADM697
FUNCTIONAL BLOCK DIAGRAMS
BATT ON
VBATT
VOUT
VCC
LLIN
LOW LINE
RESET
RESET GENERATOR
RESET
OSC IN
APPLICATIONS
Microprocessor Systems
Computers
Controllers
Intelligent Instruments
Automotive Systems
Critical P Power Monitoring
OSC SEL
TIMEBASE FOR RESET
AND WATCHDOG
WATCHDOG
INPUT (WDI)
WATCHDOG
TRANSITION DETECTOR
WATCHDOG
TIMER
WATCHDOG
OUTPUT (WDO)
ADM696
POWER FAIL
INPUT (PFI)
POWER FAIL
OUTPUT (PFO)
1.3V
GENERAL DESCRIPTION
The ADM696/ADM697 supervisory circuits offer 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 ADM696/ADM697 are available in 16-pin DIP and small
outline packages and provide the following functions:
CEIN
CEOUT
LLIN
LOW LINE
RESET
RESET GENERATOR
RESET
OSC IN
1. Power-On Reset output during power-up, power-down and
brownout conditions. The RESET voltage threshold is
adjustable using an external voltage divider. The RESET
output remains operational with VCC as low as 1 V.
OSC SEL
TIMEBASE FOR RESET
AND WATCHDOG
WATCHDOG
INPUT (WDI)
WATCHDOG
TRANSITION DETECTOR
2. A Reset pulse if the optional watchdog timer has not been
toggled within specified time.
POWER FAIL
INPUT (PFI)
3. Separate watchdog time-out and low line status outputs.
WATCHDOG
TIMER
WATCHDOG
OUTPUT (WDO)
ADM697
1.3V
POWER FAIL
OUTPUT (PFO)
4. Adjustable reset and watchdog timeout periods.
5. A 1.3 V threshold detector for power fail warning, low battery detection, or to monitor a power supply other than VCC.
6. Battery backup switching for CMOS RAM, CMOS microprocessor or other low power logic (ADM696).
7. Write protection of CMOS RAM or EEPROM (ADM697).
The ADM696/ADM697 is fabricated using an advanced epitaxial
CMOS process combining low power consumption (5 mW),
extremely fast Chip Enable gating (5 ns) and high reliability.
RESET assertion is guaranteed with VCC as low as 1 V. In
addition, the power switching circuitry is designed for minimal
voltage drop thereby permitting increased output current drive
of up to 100 mA without the need for an external pass transistor.
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.
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Tel: 617/329-4700
Fax: 617/326-8703
