3 V, Voltage Monitoring
Microprocessor Supervisory Circuits
ADM706P/ADM706R/ADM706S/ADM706T, ADM708R/ADM708S/ADM708T
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
Debounced manual reset input (MR)
Independent watchdog timer
1.6 sec timeout (ADM706P, ADM706R, ADM706S,
ADM706T)
Reset output
Active high (ADM706P)
Active low (ADM706R, ADM706S, ADM706T)
Both active high and active low (ADM708R, ADM708S,
ADM708T)
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
WATCHDOG
INPUT (WDI)
WATCHDOG
TRANSITION
DETECTOR
VCC
70μA
MR
VREF*
1.25V
RESET,
(P = RESET)
POWER-FAIL
OUTPUT (PFO)
* VOLTAGE REFERENCE = 2.63V (P/R), 2.93V (S), 3.08V (T)
Figure 1. ADM706P/ADM706R/ADM706S/ADM706T
VCC
70μA
MR
POWER-FAIL
INPUT (PFI)
RESET
RESET
GENERATOR
VREF *
Microprocessor systems
Computers
Controllers
Intelligent instruments
Critical microprocessor monitoring
Battery operated systems
Portable instruments
ADM706P/ADM706R/
ADM706S/ADM706T
POWER-FAIL
INPUT (PFI)
WATCHDOG
OUTPUT (WDO)
RESET AND
WATCHDOG
TIMEBASE
RESET
GENERATOR
VCC
VCC
APPLICATIONS
WATCHDOG
TIMER
06435-001
FEATURES
ADM708R/ADM708S/
ADM708T
1.25V
RESET
POWER-FAIL
OUTPUT (PFO)
* VOLTAGE REFERENCE = 2.63V (R), 2.93V (S), 3.08V (T)
06435-002
Data Sheet
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 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
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.
Rev. E
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 ADM708R/ADM708S/ADM708T provide similar functionality 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
active low (RESET) output.
All devices are available in narrow 8-lead PDIP and 8-lead
SOIC packages.
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