STM6823 datasheet(5/21 Pages) STMICROELECTRONICS

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STM6321/6322/6821/6822/6823/6824/6825

Pin Descriptions

Active-Low, Push-pull Reset Output (RST) -

STM6822/6823/6824/6825. Pulses low when trig-

gered, and stays low whenever VCC is below the

reset threshold or when MR is a logic low. It re-

mains low for trec after either VCC rises above the

reset threshold, the watchdog triggers a reset, or

MR goes from low to high.

Active-Low, Open Drain Reset Output (RST) -

STM6321/6322/6822. Pulses low when triggered,

and stays low whenever VCC is below the reset

threshold or when MR is a logic low. It remains low

for trec after either VCC rises above the reset

threshold, the watchdog triggers a reset, or MR

goes from low to high. Connect a pull-up resistor

to supply voltage.

Push-button Reset Input (MR). A logic low on

MR asserts the reset output. Reset remains as-

serted as long as MR is low and for trec after MR

returns high. This active-low input has an internal

52k

Ω pull-up. It can be driven from a TTL or CMOS

logic line, or shorted to ground with a switch.

Leave open if unused.

Watchdog Input (WDI). If WDI remains high or

low for at least 1.6sec, the internal watchdog timer

expires and reset is asserted. The internal watch-

dog timer clears while reset is asserted or when

WDI sees a rising or falling edge. The watchdog

function CAN be disabled if WDI is left unconnect-

ed or is connected to a tri-state buffer output.

Active-High Reset Output. Active-high,

push-

pull reset output; inverse of RST.

Table 3. Pin Functions

Figure 6. Block Diagram (STM6xxx)

Note: 1. For STM6321/6821/6822/6823/6824

2. For STM6322/6821/6822/6823/6825

3. For STM6821/ (RST output only)

4. For STM6321/6322/6824/6825 (both RST and RST outputs)

Name

Function

STM6822

STM6823

STM6821

STM6321

STM6824

STM6322

STM6825

1–

RST

Active-Low Reset Output

–4

Push-button Reset Input

–

WDI

Watchdog Input

–

RST

Active-High Reset Output

VCC

Supply Voltage

VSS

Ground

AI09132

VRST

RST (RST)

(3)

WATCHDOG

TIMER

WDI

Transitional

Detector

COMPARE

trec

Generator

VCC

WDI

(1)

(2)

RST

(4)

VCC

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