TC1270ASVRCTR Microchip Technology, TC1270ASVRCTR Datasheet - Page 27

• Manufacturer Part Number: TC1270ASVRCTR
• Description: IC,Power Supply Supervisor,TO-253,4PIN,PLASTIC
• Manufacturer: Microchip Technology
• Type: Simple Reset/Power-On Resetr

Specifications of TC1270ASVRCTR

• Number Of Voltages Monitored: 1
• Output: Push-Pull, Totem Pole
• Reset: Active Low
• Reset Timeout: 140 ms Minimum
• Voltage - Threshold: 2.93V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: SOT-143, SOT-143B, TO-253AA
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

5.6
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 k resistor in series with the output of the
TC127XA
in the system that 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 5-7:
TC1271A Push-Pull Output to a Bidirectional
Reset I/O pin.
5.7
Figure 5-8
TC1270A, TC1270AN and TC1271A devices. Devices
that are in the 3-pin SOT-23 package could be used in
that circuit with the loss of manual Reset functionality.
Examples of compatible footprint devices in the SOT-
23-3 package are the MCP111, MCP112, TC54, and
TC51 devices. This allows the system to be designed
to offer a “base” functionality and a higher end system
with the “enhanced” functionality, which includes a
manual Reset.
FIGURE 5-8:
Comparison.
 2010 Microchip Technology Inc.
V
V
NC
MR
DD
DD
TC1270A/71A
MR
1
2
3
SOT-23-5
Controllers and Processors With
Bidirectional I/O Pins
Migration Paths
V
V
(Figure
SS
DD
shows the 5-pin SOT-23 footprint of the
RST
or
RST
4
5
5-7). If there are other components
V
RST
or
RST
SS
4.7 k
Interfacing the TC1270A or
SOT-23 5-pin to 3-pin
V
Reset I/O
DD
V
V
3
SS
SOT-23-3
DD
Buffered
Reset to
system
1
2
RST
or
RST
V
SS
5.8
The TC1270A and TC1271A Reset output is valid
down to V
becomes an “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 shut down well above this volt-
age. However, in situations where the Reset signal
must be maintained valid to V
is required.
For devices where the Reset signal is active-low, a
pull-down resistor must be connected from the
TC1270A RST pin to ground to discharge stray
capacitances and hold the output low
Similarly for devices where the Reset signal is
active-high, a pull-up resistor to V
ensure a valid high RST signal for V
(Figure
This resistor value, though not critical, should be
chosen such that it does not appreciably load the Reset
pin under normal operation (100 k should be suitable
for most applications).
FIGURE 5-9:
Reset pin output state as V
FIGURE 5-10:
Reset pin output state as V
TC1270A/70AN/71A
5-10).
Reset Signal Integrity During
Power-Down
DD
MR
MR
TC1270A
TC1271A
= 1.0V. Below this voltage the output
V
V
V
V
V
V
SS
SS
DD
DD
DD
DD
Ensuring a valid active-low
Ensuring a valid active-high
RST
RST
DD
DD
DD
= 0V, external circuitry
approaches 0V.
approaches 0V.
R
100 k
R
100 k
DD
DS22035C-page 27
1
1
(Figure
DD
is required to
below 1.0V
5-9).