3 V, Voltage Monitoring
Microprocessor Supervisory Circuits
ADM706P/ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ADM708T
FEATURES
FUNCTIONAL BLOCK DIAGRAMS
Precision supply voltage monitor
2.63 V (ADM706P, ADM706R, ADM708R)
2.93 V (ADM706S, ADM708S)
3.08 V (ADM706T, ADM708T)
100 μA quiescent current
200 ms reset pulse width
MR
WATCHDOG
WATCHDOG
WATCHDOG
INPUT (WDI)
TRANSITION
DETECTOR
WATCHDOG
OUTPUT (WDO)
TIMER
V
RESET AND
WATCHDOG
TIMEBASE
CC
70μA
MR
RESET,
(P = RESET)
RESET
GENERATOR
Debounced manual reset input (
Independent watchdog timer
1.6 second timeout (ADM706x)
Reset output
)
V
CC
V
*
REF
ADM706P/ADM706R/
ADM706S/ADM706T
POWER-FAIL
INPUT (PFI)
POWER-FAIL
Active high (ADM706P)
OUTPUT (PFO)
1.25V
Active low (ADM706R, ADM706S, ADM706T)
Both active high and active low (ADM708R, ADM708S,
ADM708T)
*
VOLTAGE REFERENCE = 2.63V (P/R), 2.93V (S), 3.08V (T)
Figure 1. ADM706P/ADM706R/ADM706S/ADM706T
Voltage monitor for power-fail or low battery warning
V
CC
RESET
Guaranteed
valid with VCC = 1 V
70μA
RESET
RESET
Superior upgrade for MAX706P/R/S/T, MAX708R/S/T
MR
RESET
GENERATOR
APPLICATIONS
V
CC
Microprocessor systems
Computers
Controllers
V
*
REF
ADM708R/ADM708S/
ADM708T
POWER-FAIL
INPUT (PFI)
POWER-FAIL
OUTPUT (PFO)
1.25V
Intelligent instruments
Critical microprocessor monitoring
Battery-operated systems
Portable instruments
* VOLTAGE REFERENCE = 2.63V (R), 2.93V (S), 3.08V (T)
Figure 2. ADM708R/ADM708S/ADM708T
GENERAL DESCRIPTION
The ADM706P/ADM706R/ADM706S/ADM706T and the
ADM708R/ADM708S/ADM708T microprocessor supervisory
circuits are suitable for monitoring either 3 V or 3.3 V power
supplies.
The ADM706R, ADM706S, and 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.
The ADM706P/ADM706R/ADM706S/ADM706T provide
power-supply monitoring circuitry that generate a reset output
during power-up, power-down, and brownout conditions. The
reset output remains operational with VCC as low as 1 V.
Independent watchdog monitoring circuitry is also provided.
This is activated if the watchdog input has not been toggled
within 1.6 seconds.
The ADM708R/ADM708S/ADM708T provide similar functio-
nality as the ADM706R/ADM706S/ADM706T 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
RESET
active low ( ) output.
All parts are available in narrow 8-lead PDIP and 8-lead SOIC
packages.
In addition, there is a 1.25 V threshold detector for power-fail
warning, low battery detection, or to monitor an additional power
MR
supply. An active low debounced
input is also included.
Rev. C
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