Datasheet

 2002-2012 Microchip Technology Inc. Preliminary DS21370D-page 7
TC1232
4.0 OPERATIONAL DESCRIPTION
4.1 Power Monitor
The TC1232 provides the function of warning the
processor of a power failure. When V
CC
is detected as
being below the voltage levels defined by the TOL pin,
the TC1232’s comparator outputs the RST and RST
signals to a logic level that warns the system of an out-
of-tolerance power supply. The RST and RST
signals
switch at a threshold value of 4.5V if TOL is tied to V
CC
,
and at a value of 4.75 volts if TOL is grounded. The
RST and RST signals are held active for a minimum of
250 ms to ensure that the power supply voltage has
been stabilized.
Figure 4-1 shows the V
CC
fall time.
Figure 4-2 shows the V
CC
rise time.
Figure 4-3 shows the time from when the voltage trip
point is detected to the reset output pin going active.
Figure 4-4 shows the time from when the voltage trip
point is exited to the reset output pin going inactive.
FIGURE 4-1: Power-Down Slew Rate.
FIGURE 4-2: Power-up Slew Rate.
FIGURE 4-3: V
CC
Detect Reset Output
Delay (Power-Down).
FIGURE 4-4: V
CC
Detect Reset Output
Delay (Power-Up).
+4.75V
t
F
V
CC
+4.25V
t
R
V
CC
+4.25V
+4.75V
V
CC
= 5V
+4.5V (5% Trip Point)
+4.25V (10% Trip Point)
RST
RST
V
OL
V
OH
t
RPD
V
CC
SLEW RATE = 1.66 mV/µs (0.5V/300 µs)
V
CC
4.6V (5% Trip Point)
4.5V(10% Trip Point)
RST
RST
V
OL
V
OH
t
RPU