ECONOMONITOR™ – 3-PIN SYSTEM SUPERVISOR
WITH POWER SUPPLY MONITOR AND WATCHDOG
TC32M
1
t
ST
RS
V
STH
(MIN)
V
STL
(MAX)
V
STL
(MIN)
t
TD
V
DD
V
RST
2
t
RPD
t
RST
V
IH
V
IL
RS
Note: t
TD
is the maximum elapsed time between strobes which
will keep the watchdog timer from forcing RS LOW.
(A
STROBE
is defined as a high-to-low transition from V
STH
to V
STL
)
.
3
4
5
Figure 1. Watchdog Strobe
Figure 3. Power Up / Down Reset Timing
PB CLOSED
PB OPEN
RS
V
IH
V
IL
t
RST
Figure 2. RS Pulled Low by Push-button Reset
6
7
PIN DESCRIPTION
Pin No.
1
2
3
Symbol
GND
V
DD
RS
Description
Ground.
The +5V power supply input.
RESET/STROBE (Bidirectional). The open drain goes active if:
1. V
DD
falls below 4.5V nominal.
2. If pulled low by an external electronic signal or switch closure.
3. If the watchdog is not strobed within the minimum watchdog timeout period.
4. During power-up and power-down.
In the input mode, RS connects to a voltage level shift network (typically a resistor divider
to V
DD
.) The watchdog timer is reset when processor causes a voltage level
≤
V
STL
to be
applied to RS.
The +5V power supply input. (SOT-223 only).
4
V
DD
8
TELCOM SEMICONDUCTOR, INC.
5-5
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