TC1271FERCTR Microchip Technology, TC1271FERCTR Datasheet - Page 6

• Manufacturer Part Number: TC1271FERCTR
• Description: IC RESET MONITOR 1.75V SOT143-4
• Manufacturer: Microchip Technology
• Type: Simple Reset/Power-On Resetr

Specifications of TC1271FERCTR

• Number Of Voltages Monitored: 1
• Output: Push-Pull, Totem Pole
• Reset: Active High
• Reset Timeout: 140 ms Minimum
• Voltage - Threshold: 1.75V
• 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

TC1270/TC1271
4.0
4.1
The
monitoring and Reset timing during power-up,
power-down, and brownout/sag conditions, and rejects
negative-going transients (glitches) on the power
supply line.
duration vs. maximum negative excursion (overdrive)
for glitch rejection. Any combination of duration and
overdrive that lays under the curve will not generate a
Reset signal. Combinations above the curve are
detected as a brown-out or power-down. Transient
immunity can be improved by adding a capacitor in
close proximity to the V
FIGURE 4-1:
Duration vs. Overdrive for Glitch Rejection at
+25°C.
4.2
The TC1270 RESET output is valid to V
Below this voltage the output becomes an “open circuit”
and does not sink current. This means CMOS logic
inputs to the microprocessor will be floating at an
undetermined voltage. Most digital systems are
completely shut down well above this voltage.
However, in situations where RESET must be
maintained valid to V
DS21381D-page 6
TC1270/TC1271
400
320
240
160
80
APPLICATIONS INFORMATION
V
Reset Signal Integrity During
Power-Down
0
V
CC
CC
1
Figure 4-3
T
TC127xR/S/T
RESET COMPARATOR OVERDRIVE,
A
Transient Rejection
= +25°C
CC
10
Maximum Transient
CC
shows the maximum transient
V
= 0V, a pull-down resistor must
TC127LMJ
TH
Duration
pin of the TC1270/TC1271.
provides
- V
CC
(mV)
100
Overdrive
V
accurate
TH
CC
1000
= 1.0V.
V
CC
be connected from RESET to ground to discharge stray
capacitances and hold the output low
resistor value, though not critical, should be chosen
such that it does not appreciably load RESET under
normal operation
applications). Similarly, a pull-up resistor to V
required for the TC1271 to ensure a valid high RESET
for V
FIGURE 4-2:
V
4.3
Some microprocessor’s (such as Motorola 68HC11)
have bidirectional Reset pins. Depending on the
current drive capability of the processor pin, an indeter-
minate 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 TC1270/TC1271
(Figure
tem which require a Reset signal, they should be buff-
ered so as not to load the Reset line. If the other
components are required to follow the Reset I/O of the
microprocessor, the buffer should be connected as
shown with the solid line.
FIGURE 4-3:
Reset I/O.
V
CC
CC
CC
= 0V.
TC1270
V
GND
4-3). If there are other components in the sys-
below 1.1V.
CC
Processors With Bidirectional
I/O Pins
RESET
TC1270
4.7k
V
GND
(100 kΩ will be suitable for most
V
CC
Ensuring RESET Valid to
Interfacing to Bidirectional
CC
RESET
© 2007 Microchip Technology Inc.
RESET
Buffer
GND
V
μP
CC
100k
(Figure
R1
Buffered RESET
To Other System
Components
4-2). This
CC
is