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Microprocessor Supervisors and Reset ICs
Supervisor Family with Integrated Watchdog

Reset + Watchdog Supervisor Datasheet (STM6321/22 and STM6821/22/23/24/25)
New STM682x Supervisor Family with WatchdogA Reset circuit monitors the system power and provides the Power-on Reset signal that initializes the processor, holding it in reset mode a short time to allow the system power to become stable. It continues to monitor the system power, and if low voltage is detected, it resets the processor. These two functions are called "Power-on Reset/Low Voltage Detection" (POR-LVD), and they ensure proper operation of the system.

ST offers a series of 3- and 4-pin Reset IC families that provide POR-LVD. The 4-pin versions include Manual Reset inputs. The family of 5-pin Reset devices includes Watchdog timers that protect against runaway software.

POR-LVD and Watchdog are features that make systems more robust, more tolerant of real world events that can disrupt system operation.
200ms (typ) trec
Watchdog Timer - 1.6s (typ)
Manual Reset Input (/MR)
Low Supply Current - 3µA (typ)
Guaranteed /RST (RST) Assertion Down to Vcc = 1.0V
–40°C to +85°C
Reset + Watchdog Supervisor Parametric Data
Part Number
(click for Parametric Data)(1)		 Watchdog
Input 		Manual
Reset Input		 Reset Output
Active-Low
(Push-pull)		 Active- High
(Push-pull)		 Active-Low
(Open Drain)
STM6321 Watchdog Feature ' ' Active-High (Push-pull) Active-Low (Open Drain)
STM6322 ' Manual Reset Input Feature ' Active-High (Push-pull) Active-Low (Open Drain)
STM6821 Watchdog Feature Manual Reset Input Feature ' Active-High (Push-pull) '
STM6822 Watchdog Feature Manual Reset Input Feature ' ' Active-Low (Open Drain)
STM6823 Watchdog Feature Manual Reset Input Feature Active-Low (Push-pull) ' '
STM6824 Watchdog Feature ' Active-Low (Push-pull) Active-High (Push-pull) '
STM6825 ' Watchdog Feature Active-Low (Push-pull) Active-High (Push-pull) '
Notes: (1) Vrst (nom, V) voltages range from 2.32V to 4.65V.
STM6821 Reset + Watchdog Supervisor Block Diagram
STM6821 5-pin Supervisor Block Diagram
Small Packages
5-pin Supervisor SOT23-5L Package
SOT23-5L Package		   The Reset + Watchdog Supervisor family comes in a tiny SOT23-5L package, measuring 1.5 x 2.8mm (nominal).

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