ADM8690(1997) Ver la hoja de datos (PDF) - Analog Devices
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ADM8690 Datasheet PDF : 16 Pages
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Microprocessor
Supervisory Circuits
ADM8690–ADM8695
FEATURES
Upgrade for ADM690/ADM695, MAX690–MAX695
Specified Over Temperature
Low Power Consumption (0.7 mW)
Precision Voltage Monitor
Reset Assertion Down to 1 V VCC
Low Switch On-Resistance 0.7 ⍀ Normal,
7 ⍀ in Backup
High Current Drive (100 mA)
Watchdog Timer—100 ms, 1.6 s, or Adjustable
400 nA Standby Current
Automatic Battery Backup Power Switching
Extremely Fast Gating of Chip Enable Signals (3 ns)
Voltage Monitor for Power Fail
Available in TSSOP Package
APPLICATIONS
Microprocessor Systems
Computers
Controllers
Intelligent Instruments
Automotive Systems
GENERAL DESCRIPTION
The ADM8690–ADM8695 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 complete family provides a variety of configurations to sat-
isfy most microprocessor system requirements.
The ADM8690, ADM8692 and ADM8694 are available in
8-pin DIP packages and provide:
1. Power-on reset output during power-up, power-down and
brownout conditions. The RESET output remains opera-
tional with VCC as low as 1 V.
2. Battery backup switching for CMOS RAM, CMOS
microprocessor or other low power logic.
3. A reset pulse if the optional watchdog timer has not been
toggled within a specified time.
4. A 1.3 V threshold detector for power fail warning, low battery
detection or to monitor a power supply other than +5 V.
The ADM8691, ADM8693 and ADM8695 are available in
16-pin DIP and small outline packages (including TSSOP) and
provide three additional functions:
1. Write protection of CMOS RAM or EEPROM.
2. Adjustable reset and watchdog timeout periods.
3. Separate watchdog timeout, backup battery switchover, and
low VCC status outputs.
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.
FUNCTIONAL BLOCK DIAGRAMS
VBATT
VCC
VOUT
4.65V1
RESET
GENERATOR2
RESET
WATCHDOG
INPUT (WDI)
POWER FAIL
INPUT (PFI)
WATCHDOG
TRANSITION DETECTOR
(1.6s)
ADM8690
ADM8692
ADM8694
1.3V
POWER FAIL
OUTPUT (PFO)
1VOLTAGE DETECTOR = 4.65V (ADM8690, ADM8694)
4.40V (ADM8692)
2RESET PULSE WIDTH = 50ms (AD8690, ADM8692)
200ms (ADM8694)
VBATT
BATT ON
VCC
CEIN
4.65V1
OSC IN
OSC SEL
RESET AND
WATCHDOG
TIMEBASE
ADM8691
ADM8693
ADM8695
VOUT
CEOUT
LOW LINE
RESET
GENERATOR
RESET
RESET
WATCHDOG
INPUT (WDI)
POWER FAIL
INPUT (PFI)
WATCHDOG
TRANSITION DETECTOR
1.3V
WATCHDOG
TIMER
WATCHDOG
OUTPUT (WDO)
POWER FAIL
OUTPUT (PFO)
1VOLTAGE DETECTOR = 4.65V (ADM8691, ADM8695)
4.40V (ADM8693)
The ADM8690–ADM8695 family is fabricated using an ad-
vanced epitaxial CMOS process combining low power con-
sumption (0.7 mW), extremely fast Chip Enable gating (3 ns)
and high reliability. RESET assertion is guaranteed with VCC as
low as 1 V. In addition, the power switching circuitry is de-
signed for minimal voltage drop thereby permitting increased
output current drive of up to 100 mA without the need of an
external pass transistor.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 617/329-4700 World Wide Web Site: http://www.analog.com
Fax: 617/326-8703
© Analog Devices, Inc., 1997
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