TCM811MERCTR Microchip Technology, TCM811MERCTR Datasheet - Page 7

• Manufacturer Part Number: TCM811MERCTR
• Description: IC RESET MONITOR 4.38V SOT143-4
• Manufacturer: Microchip Technology
• Type: Simple Reset/Power-On Resetr

Specifications of TCM811MERCTR

• Number Of Voltages Monitored: 1
• Output: Push-Pull, Totem Pole
• Reset: Active Low
• Reset Timeout: 140 ms Minimum
• Voltage - Threshold: 4.38V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-143, SOT-143B, TO-253AA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

4.0
The
monitoring and reset timing during power-up, power-
down, and brownout/sag conditions. These devices
also reject negative-going transients (glitches) on the
power supply line.
transient duration vs. maximum negative excursion
(overdrive) for glitch rejection. Any combination of
duration and overdrive that is under the curve will not
generate a reset signal. Combinations above the curve
are detected as a brownout or power-down. Transient
immunity can be improved by adding a 0.1 µF capacitor
in close proximity to the V
TCM812.
FIGURE 4-1:
vs. Overdrive for Glitch Rejection at +25°C.
4.1
The TCM811 RESET push-pull output is valid to
V
"open circuit" and does not sink current. This means
CMOS logic inputs to the microcontroller will be floating
at an undetermined voltage. Most digital systems are
completely shutdown well above this voltage. How-
ever, in situations where RESET must be maintained
valid to V
nected from RESET to ground to discharge
capacitances and hold the output low
resistor value, though not critical, should be chosen
© 2007 Microchip Technology Inc.
DD
= 1.0V. Below this voltage the output becomes an
TCM811/TCM812
400
320
240
160
APPLICATIONS INFORMATION
80
RESET Signal Integrity During
Power-Down
DD
0
V
1
DD
RESET COMPARATOR OVERDRIVE,
T
= 0V, a pull-down resistor must be con-
TCM81xR/S/T
A
= +25˚C
Maximum Transient Duration
Figure 4-1
V TH - V DD (mV)
10
TCM81xL/M
Duration
provides
DD
100
shows the maximum
Overdrive =
pin of the TCM811/
V
TH
(Figure
accurate
1000
V
D D
4-2). This
stray
V
DD
such that it does not appreciably load RESET under
normal operation (100 kΩ will be suitable for most
applications). Similarly, a pull-up resistor to V
required for the TCM812 to ensure a valid high RESET
for V
FIGURE 4-2:
RESET output of the TCM811 ensures that the
RESET output is valid to V
4.2
Some microcontrollers have bidirectional reset pins.
Depending on the current drive capability of the
controller pin, an indeterminate logic level may result if
there is a logic conflict. This can be avoided by adding
a 4.7 kΩ resistor in series with the output of the
TCM811/TCM812
components in the system which require a reset signal,
they should be buffered so as not to load the reset line.
If the other components are required to follow the reset
I/O of the microcontroller, the buffer should be
connected as shown with the solid line.
FIGURE 4-3:
Bidirectional Reset I/O.
0.1µF
DD
0.1µF
below 1.1V.
Controllers and Processors With
Bidirectional I/O Pins
V
TCM811/TCM812
DD
TCM811
GND
RESET
1
4
(Figure
TCM811
The addition of R
Interfacing the TCM811 to a
GND
V
V
DD
2
RESET
DD
4.7 kΩ
4
1
4-3). If there are other
BUFFER
DD
= 0V.
2
RESET
controller
DS21615C-page 7
Buffered RESET
To Other System
Components
Micro
GND
R
100 kΩ
1
1
at the
DD
is