MCP1316 Microchip Technology, MCP1316 Datasheet - Page 29

• Manufacturer Part Number: MCP1316
• Description: Voltage Supervisor
• Manufacturer: Microchip Technology

4.3
The minimum pulse width (time) required to cause a
Reset may be an important criteria in the implementa-
tion of a Power-on Reset (POR) circuit. This time is
referred to as transient duration. The MCP131X/2X
devices are designed to reject a level of negative-going
transients (glitches) on the power supply line.
Transient duration is the amount of time needed for
these supervisory devices to respond to a drop in V
The transient duration time (t
magnitude of V
of duration and overdrive that lies under the dura-
tion/overdrive curve will not generate a Reset signal.
Generally speaking, the transient duration time
decreases with and increases in the V
age. Combinations of duration and overdrive that lies
above the duration/overdrive curve are detected as a
brown-out or power-down condition.
Figure 4-16 shows a typical transient duration vs.
Reset
MCP131X/2X will not generate a Reset pulse. It shows
that the farther below the trip point the transient pulse
goes, the duration of the pulse required to cause a
Reset gets shorter. Figure 4-16 shows the transient
response characteristics for the MCP131X/2X.
Transient immunity can be improved by adding a
bypass capacitor (typically 0.1 μF) as close as possible
to the V
FIGURE 4-16:
Transient Duration Waveform.
© 2005 Microchip Technology Inc.
5V
0V
DD
Negative Going V
comparator
pin of the MCP131X/2X device.
TRIP
– V
Time (μs)
Example of Typical
DD
overdrive,
(overdrive). Any combination
(Duration)
t
V
TRAN
(Overdrive)
TRANS
TRIP(MIN)
DD
) is dependant on the
Transients
for
- V
TRIP
DD
which
V
V
– V
TRIP(MAX)
TRIP(MIN)
DD
volt-
DD
the
.
4.4
The Manual Reset input pin (MR) allows the Reset pins
(RST/RST) to be manually forced to their active states.
The MR pin has circuitry to filter noise pulses that may
be present on the pin. Figure 4-17 shows a block dia-
gram for using the MCP131X/2X with a push button
switch. To minimize the required external components,
the MR input has an internal pull-up resistor.
A mechanical push button or active logic signal can
drive the MR input.
Once MR has been low for a time, t
Reset delay time), the Reset output pins are forced
active. The Reset output pins will remain in their active
states for the Reset delay timer time out period (t
Figure 4-18 shows a waveform for the Manual Reset
switch input and the Reset pins output.
FIGURE 4-17:
Watchdog Timer.
FIGURE 4-18:
4.4.1
The noise filter filters out noise spikes (glitches) on the
Manual Reset pin (MR). Noise spikes less than 100 ns
(typical) are filtered.
MR
RST
RST
The MR input typically ignores input pulses
of 100 ns.
Manual Reset Input
NOISE FILTER
V
IL
MR
t
MRD
MCP13XX
V
+5V
V
DD
MCP131X/2X
t
SS
MR
Push Button Reset and
MR Input – Push Button.
RST
WDI
V
PICmicro
I/O
MCLR
IH
DS21985A-page 29
t
MRD
RST
(the Manual
®
MCU
R
ST
)