Low Voltage Supervisory Circuits with
Watchdog & Manual Reset in 5-Lead SOT-23
Preliminary Technical Data
ADM6821–ADM6825
FUNCTIONAL BLOCK DIAGRAM
FEATURES
Precision Low Voltage Monitoring down to 1.8V
9 Reset Threshold Options:
1.58V to 4.63V
V
CC
140ms (Min) Reset Timeout
Watchdog Timer with 1.6s Timeout
Manual Reset Input
ADM6821
VCC
RESET
GENERATOR
RESET
Reset Output Stages
VREF
Push-Pull Active-Low
Open-Drain Active-Low
MR
DEBOUNCE
Push-Pull Active-High
WATCHDOG
DETECTOR
Low Power Consumption (3µA)
Guaranteed Reset Output valid to VCC=1V
Power Supply Glitch Immunity
Specified from -40°C to +125°C
5-Lead SOT-23 Package
GND
WDI
APPLICATIONS
Microprocessor Systems
Computers
Controllers
Intelligent Instruments
Portable Equipment
GENERAL DESCRIPTION
The ADM6821-ADM6825 are supervisory circuits which
monitor power supply voltage levels and code execution
integrity in microprocessor-based systems. As well as providing
power-on-reset signals, an on-chip watchdog timer can reset the
microprocessor if it fails to strobe within a preset timeout
period. A reset signal can also be asserted by means of an
external push-button, through a manual reset input. The three
parts feature different combinations of watchdog input, manual
reset input and output stage configuration, as shown in table 1.
Each part is available in a choice of 9 reset threshold options
ranging from 1.58V to 4.63V. The reset and watchdog timeout
periods are fixed at 140ms (min) and 1.6s (typ), respectively.
The ADM6821-ADM6825 are available in 5-lead SOT-23
packages and typically consume only 3µA, making them
suitable for use in low power portable applications.
Table 1. Selection Table
Output Stage
Part No.
Watchdog Timer
Manual Reset
RESET
RESET
ADM6821
ADM6822
ADM6823
ADM6824
ADM6825
Yes
Yes
Yes
Yes
-
Yes
Yes
Yes
-
-
Push-Pull
Open-Drain
Push-Pull
Push-Pull
Push-Pull
-
-
Push-Pull
Push-Pull
Yes
Rev. PrA
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