TC1232_13 Datasheet, PDF (8/20 Pages) Microchip Technology – Microprocessor Monitor

TC1232
4.2 Push Button Reset Input
The debounced manual reset input (PB RST) manually
forces the reset outputs into their active states.
Figure 4-5 shows a block diagram for using the
TC1232 with a push button switch.
Once PB RST has been low for a time t_PBD (the push-
button delay time), the reset outputs go active. The
reset outputs remain in their active states for a
minimum of 250 ms after PB RST rises above V_IH.
Figure 4-6 shows a waveform for the push button
switch input and the reset pins output.
A mechanical push button or active logic signal can
drive the PB RST input. The debounced input ignores
input pulses less than 1 ms and recognizes pulses of
20 ms or greater. No external pull-up resistor is
required because the PB RST input has an internal
pull-up to V_CC of approximately 100 µA.
+5V
V_CC
TD
PB RST ST
TC1232
RST
I/O
Microprocessor
Reset
GND TOL
FIGURE 4-5:
Push Button Reset and
Watchdog Timer.
t_PB
PB RST
t_PBD
V_IL
RST
RST
V_IH
t_RST
The debounced PB RST input ignores input pulses less
than 1 ms and is designed to recognize pulses of
20 ms or greater.
FIGURE 4-6:
PB RST Input.
Push Button Reset –
DS21370D-page 8
Preliminary
 2002-2012 Microchip Technology Inc.