+3 V, Voltage Monitoring
a
P Supervisory Circuits
ADM706P/R/S/T, ADM708R/S/T
FUNCTIONAL BLOCK DIAGRAMS
FEATURES
Precision Supply-Voltage Monitor
+2.63 V (ADM706P/R, ADM708R)
+2.93 V (ADM706S, ADM708S)
+3.08 V (ADM706T, ADM708T)
100 A Quiescent Current
WATCHDOG
WATCHDOG
WATCHDOG
OUTPUT(WDO)
WATCHDOG
TIMER
INPUT (WDI)
TRANSITION
DETECTOR
RESET &
WATCHDOG
TIMEBASE
200 ms Reset Pulsewidth
V
CC
Debounced Manual Reset Input (MR)
Independent Watchdog Timer—1.6 sec Timeout
(ADM706x)
70A
MR
RESET
GENERATOR
RESET,
(P = RESET)
Reset Output
Active High (ADM706P)
Active Low (ADM706R/S/T)
V
CC
V
*
Both Active High and Active Low (ADM708R/S/T)
Voltage Monitor for Power-Fail or Low Battery Warning
Guaranteed RESET Valid with VCC = 1 V
Superior Upgrade for MAX706P/R/S/T, MAX708R/S/T
REF
ADM706
POWER FAIL
INPUT (PFI)
POWER FAIL
OUTPUT (PFO)
1.25V
*VOLTAGE REFERENCE = 2.63V (P/R), 2.93V (S), 3.08V (T)
APPLICATIONS
Microprocessor Systems
Computers
V
CC
Controllers
RESET
Intelligent Instruments
Critical P Monitoring
Automotive Systems
Battery Operated Systems
Portable Instruments
70A
MR
RESET
GENERATOR
RESET
V
CC
V
*
REF
ADM708
GENERAL DESCRIPTION
POWER FAIL
INPUT (PFI)
The ADM706P/R/S/T and the ADM708R/S/T microprocessor
supervisory circuits are suitable for monitoring either 3 V or 3.3 V
power supplies.
POWER FAIL
OUTPUT (PFO)
1.25V
*VOLTAGE REFERENCE = 2.63V (R), 2.93V (S), 3.08V (T)
The ADM706P/R/S/T provide the following functions:
1. Power-supply monitoring circuitry which generates a Reset
output during power-up, power-down and brownout condi-
tions. The reset output remains operational with VCC as low
as 1 V.
The ADM708R/S/T provide the same functionality as the
ADM706R/S/T and only differ in that:
1. A watchdog timer function is not available.
2. Independent watchdog monitoring circuitry which is acti-
vated if the watchdog input has not been toggled within
1.6 seconds.
2. An active high reset output (RESET) in addition to the
active low (RESET) output is available.
All parts are available in 8-lead DIP and narrow SOIC packages.
3. A 1.25 V threshold detector for power fail warning, low bat-
tery detection, or to monitor an additional power supply.
4. An active low debounced manual reset input (MR).
The ADM706R, ADM706S, ADM706T are identical except for
the reset threshold monitor levels which are 2.63 V, 2.93 V, and
3.08 V respectively. The ADM706P is identical to the ADM706R
in that the reset threshold is 2.63 V. It differs only in that it has
an active high reset output.
REV. A
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© Analog Devices, Inc., 1999