
MCP131X/2X
DS21985A-page 26
2005 Microchip Technology Inc.
4.1
Reset Voltage Trip Point (V
TRIP
)
Operation
The device’s Reset voltage trip point (V
) is selected
when the device is ordered. As the voltage on the
device’s V
DD
pin is above or below this selected trip
point, the output of the Reset pin (RST/RST) will be
forced to either the inactive or active state.
For the voltage trip point, there is a minimum trip voltage
(V
TRIPMIN
) and a maximum trip voltage (V
TRIPMAX
). The
voltage that the device “actually” trips at will be referred
to as V
TRIP
. The trip voltage is specified for the falling of
the device V
DD
.
There is also a hysteresis (V
HYS
) on the trip point. This
is so that noise on the device voltage (V
DD
) does not
cause the Reset pin (RST/RST) to “jitter” (change
between driving an active and inactive).
The Reset pin (RST or RST) will be force active if any
of the following occur:
The Manual Reset input (MR) goes low
The Watchdog Timer times out
V
DD
goes below the threshold
During device power up
After the device exits the Reset condition, the delay
circuitry will hold the RST and RST pins active until the
appropriate Reset delay time (t
RST
) has elapsed.
TABLE 4-1:
RESET PIN STATES
Device
State of RST Pin when:
State of RST
(3)
Pin when:
Ouput Driver
V
DD
<
V
TRIP
V
DD
> V
TRIP
+
V
HYS
V
DD
<
V
TRIP
V
DD
> V
TRIP
+
V
HYS
MCP1316
L
H
—
—
Push-pull
Open-drain
(2)
MCP1316M
L
H
(2)
—
—
MCP1317
—
—
H
L
Push-pull
MCP1318
L
H
H
L
Push-pull
Open-drain
(2)
MCP1318M
L
H
(2)
H
L
MCP1319
L
H
H
L
Push-pull
Open-drain
(2)
Open-drain
(1)
Open-drain
(1)
Open-drain
(1)
MCP1319M
L
H
(2)
H
(1)
H
(1)
H
(1)
H
L
MCP1320
L
—
—
MCP1321
L
H
L
MCP1322
L
H
L
Note 1:
Requires External Pull-up resistor.
Has Internal Pull-up resistor.
The RST pin output is always push-pull.
2:
3: