3 V, Voltage Monitoring
Microprocessor Supervisory Circuits
Data Sheet
FEATURES
Precision supply voltage monitor
2.63 V (ADM706P,
2.93 V (ADM706S,
3.08 V (ADM706T,
100 µA quiescent current
200 ms reset pulse width
Debounced manual reset input (MR)
Independent watchdog timer
1.6 sec timeout (ADM706P,
Reset output
Active high (ADM706P)
Active low (ADM706R,
Both active high and active low (ADM708R,
Voltage monitor for power fail or low battery warning
Guaranteed RESET valid with V
CC
= 1 V
Superior upgrade for MAX706P/R/S/T, MAX708R/S/T
WATCHDOG
INPUT (WDI)
FUNCTIONAL BLOCK DIAGRAMS
WATCHDOG
TRANSITION
DETECTOR
V
CC
70μA
MR
V
CC
V
REF
*
POWER-FAIL
INPUT (PFI)
1.25V
WATCHDOG
TIMER
RESET AND
WATCHDOG
TIMEBASE
RESET,
(P = RESET)
WATCHDOG
OUTPUT (WDO)
RESET
GENERATOR
ADM706P/ADM706R/
ADM706S/ADM706T
* VOLTAGE REFERENCE = 2.63V (P/R), 2.93V (S), 3.08V (T)
Figure 1.
V
CC
70μA
MR
V
CC
V
REF
*
POWER-FAIL
INPUT (PFI)
RESET
GENERATOR
RESET
RESET
APPLICATIONS
Microprocessor systems
Computers
Controllers
Intelligent instruments
Critical microprocessor monitoring
Battery operated systems
Portable instruments
ADM708R/ADM708S/
ADM708T
* VOLTAGE REFERENCE = 2.63V (R), 2.93V (S), 3.08V (T)
Figure 2.
GENERAL DESCRIPTION
The
and the
microprocessor supervisory
circuits are suitable for monitoring either 3 V or 3.3 V power
supplies.
The
provide
power supply monitoring circuitry that generate a reset output
during power-up, power-down, and brownout conditions. The
reset output remains operational with V
CC
as low as 1 V.
Independent watchdog monitoring circuitry is also provided. This
activates if the watchdog input does not toggle within 1.6 sec.
In addition, there is a 1.25 V threshold detector for a power fail
warning, low battery detection, or to monitor an additional
power supply. An active low debounced MR input is also
included.
The
and
are identical except
for the reset threshold monitor levels, which are 2.63 V, 2.93 V, and
3.08 V, respectively. The
is identical to the
in that the reset threshold is 2.63 V. It differs only in that it has
an active high reset output.
The
provide similar functio-
nality as the
and only differ
in that a watchdog timer function is not available. Instead, an
active high reset output (RESET) is provided in addition to the
active low (RESET) output.
All devices are available in narrow 8-lead PDIP and 8-lead
SOIC packages.
Rev. E
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rights of third parties that may result from its use. Specifications subject to change without notice. No
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.
Trademarks and registered trademarks are the property of their respective owners.
06435-002
1.25V
POWER-FAIL
OUTPUT (PFO)
06435-001
POWER-FAIL
OUTPUT (PFO)
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