Datasheet

MCP131X/2X
DS21985D-page 32  2005-2012 Microchip Technology Inc.
4.2 Reset Delay Timer (t
RST
)
The Reset delay timer ensures that the MCP131X/2X
device will “hold” the embedded system in Reset until
the system voltage has stabilized. There are several
time-out options to better meet the requirements of
different applications. These Reset delay timer time-
outs are shown in Table 4-2. The Standard offering
time-out is typically 200 ms.
The Reset delay timer (t
RST
) starts after the device volt-
age rises above the “actual” trip point (V
TRIP
) plus the
hysteresis (V
HYS
). When the Reset delay timer times-
out, the Reset output pin (RST/RST
) is driven inactive.
TABLE 4-2: RESET DELAY TIMER
TIME OUTS
(1)
Figure 4-15 illustrates when the Reset delay timer
(t
RST
) is active or inactive.
FIGURE 4-15: Reset Power-up Timer
Waveform.
4.2.1 EFFECT OF TEMPERATURE ON
RESET POWER-UP TIMER (T
RPU
)
The Reset delay timer time-out period (t
RST
)
determines how long the device remains in the Reset
condition. This time-out is affected by both the device
V
DD
and temperature. Typical responses for different
V
DD
values and temperatures are shown in Figures 2-
33, 2-32 and 2-31.
Note: While the Reset delay timer (t
RST
) is
active, additional system current is con-
sumed.
t
RST
Units
Min Typ Max
1.0 1.4 2.0 ms
20 30 40 ms
140 200 280 ms
1120 1.6 2.24 sec

This is the
minimum time that
the Reset delay
timer will “hold” the
Reset pin active
after V
DD
rises
above
V
TRIP
+ V
HYS
This is the
maximum time
that the Reset
delay timer will
“hold” the Reset
pin active after
V
DD
rises above
V
TRIP
+ V
HYS
Note 1: Shaded rows are custom ordered time
outs.
V
TRIP
V
DD
RST
t
RST
Reset Delay
Timer Inactive
Reset
Delay
Timer
Inactive
Reset Delay Timer Active
See Figures 2-12,
2-10 and 2-11
See Figures 2-15,
2-14 and 2-13
See Figures 2-12,
2-10 and 2-11