Datasheet

MCP131X/2X
DS21985D-page 30  2005-2012 Microchip Technology Inc.
4.1 Reset Voltage Trip Point (V
TRIP
)
Operation
The device’s Reset voltage trip point (V
TRIP
) 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 state).
The Reset pin (RST or RST
) will be forced 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:
Output 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
MCP1316M LH
(2)
— — Open-drain
(2)
MCP1317 — — H L Push-pull
MCP1318 L H H L Push-pull
MCP1318M LH
(2)
H L Open-drain
(2)
MCP1319 L H H L Push-pull
MCP1319M LH
(2)
H L Open-drain
(2)
MCP1320 LH
(1)
— — Open-drain
(1)
MCP1321 LH
(1)
H L Open-drain
(1)
MCP1322 LH
(1)
H L Open-drain
(1)
Note 1: Requires External Pull-up resistor.
2: Has Internal Pull-up resistor.
3: The RST pin output is always push-pull.