M
Features
TC1272/TC1273/TC1274
General Description
The TC1272/TC1273/TC1274 are cost-effective
system supervisor circuits designed to monitor V
CC
in
digital systems and provide a reset signal to the host
processor when necessary. No external components
are required.
The reset output is driven active within 20 µsec of V
CC
falling through the reset voltage threshold. RESET is
maintained active for a minimum of 100 msec after
V
CC
rises above the reset threshold. The TC1274 has
an active-high RESET output, while the TC1272 and
TC1273 have an active-low RESET output. The
TC1272 and TC1274 each have a complimentary out-
put, while the TC1273 has an open-drain output. The
output of the TC1272 and TC1273 is valid down to V
CC
= 1.2V. The TC1274 is valid down to V
CC
= 1.8V. All
three devices are available in a 3-Pin SOT-23B
package.
The TC1272/TC1273/TC1274 devices are optimized to
reject fast transient glitches on the V
CC
line.
3-Pin Reset Monitors for 5V Systems
• Precision V
CC
Monitor for 5.0V Systems
• 100 msec Minimum RESET, RESET Output
Duration
• Output Valid to V
CC
= 1.2V
• V
CC
Transient Immunity
• Small 3-Pin SOT-23B Package
• No External Components
Applications
•
•
•
•
Computers
Embedded Systems
Battery-Powered Equipment
Critical µP Power Supply Monitoring
Package Type
3-Pin SOT-23B*
RESET
**(RESET)
1
Typical Operating Circuit
TC1272
TC1273
TC1274
V
CC
3
GND
2
V
CC
RESET
1
V
CC
RESET
Input
V
CC
2
TC1272
* 3-Pin SOT-23B is equivalent to JEDEC TO-236
**( ) is for TC1274
GND
3
Processor
GND
2003 Microchip Technology Inc.
DS21382B-page 1
TC1272/TC1273/TC1274
1.0
ELECTRICAL
CHARACTERISTICS
† Stresses above those listed under "Absolute Maximum Rat-
ings" may cause permanent damage to the device. These are
stress ratings only and functional operation of the device at
these or any other conditions above those indicated in the
operation sections of the specifications is not implied. Expo-
sure to Absolute Maximum Rating conditions for extended
periods may affect device reliability.
Absolute Maximum Ratings†
Supply Voltage (V
CC
to GND) .............................+6.0V
RESET, RESET.......................... -0.3V to (V
CC
+ 0.3V)
Input Current, V
CC
..............................................20 mA
Output Current, RESET, RESET ........................20 mA
Power Dissipation (T
A
≤
70°C)
3-Pin SOT-23B (derate 4 mW/°C above +70°C)
................................................................230 mW
Operating Temperature Range............. -40°C to +85°C
Storage Temperature Range .............. -65°C to +150°C
DC CHARACTERISTICS
Electrical Specifications:
Unless otherwise noted, T
A
= -40°C to +85°C. Typical values are at T
A
= +25°C.
Parameters
Supply Voltage
TC1272, TC1273
TC1274
Output Voltage @ 0-500 µA
Output Current @ 2.4 Volts
V
CC
= 5V TC1272
V
CC
= 4V TC1274
Output Current @ 0.4 Volts
Operating Current
V
CC
< 5.5V: TC1272, TC1274
V
CCTP
< V
CC
< 5.5V: TC1273
V
CC
< V
CCTP
: TC1273
V
CC
Trip Point (TC1272/3/4-5)
I
CC
I
CC
I
CC
V
CCTP-5
—
—
—
4.50
4.25
4.00
—
3
100
—
—
300
0
100
100
17
17
700
4.62
4.37
4.12
9
6
200
20
20
—
—
200
200
40
40
1200
4.75
4.49
4.24
—
9
300
50
50
—
—
300
300
µA
µA
µA
V
V
V
pF
kΩ
msec
µsec
µsec
µsec
nsec
msec
msec
V
CC(LOW)
= 1V, Figure 4-2
V
CC(LOW)
= 1V, Figure 4-4
Figure 4-2, Figure 4-4
Figure 4-1, Figure 4-3
Note 4,
Figure 4-1
Note 4,
Figure 4-3
Note 3
Note 3
Note 3
Note 1
Note 1
Note 1
I
OH
I
OH
I
OL
—
—
+10
10
8
30
—
—
—
mA
mA
mA
Note 2, Note 5
Note 2
V
CC
V
CC
V
OH
1.2
1.8
—
—
5.5
5.5
—
V
V
V
TC1272, TC1274
(Note 1)
Note 1
Sym
Min
Typ
Max
Units
Conditions
V
CC
– 0.5V V
CC
– 0.1V
V
CC
Trip Point (TC1272/3/4-10) V
CCTP-10
V
CC
Trip Point (TC1272/3/4-15) V
CCTP-15
Output Capacitance
Internal Pull-Up Resistor
RESET Active Time
V
CC
Detect to RESET
TC1272, TC1273
V
CC
Detect to RESET - TC1274
V
CC
Slew Rate
(V
CCTP
(MAX) to V
CCTP
(MIN))
V
CC
Slew Rate
(V
CCTP
(MIN) to V
CCTP
(MAX))
V
CC
Detect to RESET
TC1272, TC1273
V
CC
Detect to RESET - TC1274
Note 1:
2:
3:
4:
5:
C
OUT
R
P
t
RST
t
RPD1
t
RPD2
t
F
t
R
t
RPU1
t
RPU2
AC Electrical Characteristics:
T
A
= -40°C to +85°C unless otherwise noted. Typical values are at T
A
= +25°C.
All voltages referenced to ground.
Measured with V
CC
≥
2.7 volts.
Measured with RESET output open for TC1272/TC1273; measured with RESET output open for TC1274.
t
R
= 5 µsec.
A 1 kΩ external resistor may be required in some applications for proper operation of the microprocessor reset control
circuit when using the TC1273.
DS21382B-page 2
2003 Microchip Technology Inc.
TC1272/TC1273/TC1274
2.0
Note:
TYPICAL PERFORMANCE CURVES
The graphs and tables provided following this note are a statistical summary based on a limited number of
samples and are provided for informational purposes only. The performance characteristics listed herein
are not tested or guaranteed. In some graphs or tables, the data presented may be outside the specified
operating range (e.g., outside specified power supply range) and therefore outside the warranted range.
Note:
Unless otherwise indicated, T
A
= -40°C to +85°C. Typical values are at T
A
= +25°C.
Comparator Overdrive voltage (V
OD
) is defined in Figure 4-5
T
A
= 25°C
100000
V
OD
= 20mV
V
OD
= 100mV
10000
V
OD
= 200mV
V
OD
= 1V
1000
V
OD
= 2V
300
T
A
= 25°C
V
CC
TO RESET DELAY (µsec)
V
CC
TO RESET DELAY (µsec)
200
100
100
10
1
10
0
100
1000
10000
100000
0
1
2
3
4
5
V
CC
SLEW RATE (V/µsec)
COMPARATOR OVERDRIVE (V)
FIGURE 2-1:
(RESET).
V
CC
Detect to Reset
FIGURE 2-2:
Reset Delays vs.
Comparator Overdrive.
2003 Microchip Technology Inc.
DS21382B-page 3
TC1272/TC1273/TC1274
3.0
PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 3-1.
TABLE 3-1:
Pin No.
1
1
2
3
PIN FUNCTION TABLES
Symbol
RESET
RESET
V
CC
GND
Function
RESET Output (TC1272 and TC1273)
RESET Output (TC1274)
Supply voltage (1.2V to 5.5V TC1272 and TC1273; 1.8V to 5.5V TC1274)
Ground
3.1
RESET Output (RESET)
3.2
RESET Output (RESET)
The RESET output remains low while V
CC
is below the
reset voltage threshold, and for 200 msec (100 msec
min.) after V
CC
rises above reset threshold. The output
stage of the TC1272 is complimentary, while the output
stage of the TC1273 is open-drain.
The RESET output remains high while V
CC
is below the
reset voltage threshold, and for 200 msec (100 msec
min.) after V
CC
rises above reset threshold. The output
stage of the TC1274 is complimentary.
DS21382B-page 4
2003 Microchip Technology Inc.
TC1272/TC1273/TC1274
4.0
4.1
APPLICATIONS INFORMATION
Operation – Power Monitor
t
R
The TC1272/TC1273/TC1274 is designed to function
as a voltage monitor for +5V systems. These devices
provide a RESET signal to indicate that the V
CC
has
dropped below a preset voltage level that is selected by
the suffix part number. In addition, the RESET is held
active for approximately 200 ms after the power supply
has risen above the voltage threshold level to allow
time for the power supply to stabilize before system
operation commences.
V
CCTP
(MAX)
V
CCTP
(MIN)
V
CCTP
V
CC
t
RPU2
t
R
V
CCTP
(MAX)
V
CCTP
RESET
V
OL
V
CCTP
(MIN)
FIGURE 4-3:
(TC1274).
Timing Diagram – Power Up
V
CC
t
RPU1
V
OH
RESET
V
CC
V
CCTP
(MAX)
V
CCTP
t
F
V
CCTP
(MIN)
FIGURE 4-1:
Timing Diagram – Power Up
(TC1272/TC1273).
V
OH
RESET
V
CCTP
(MAX)
V
CCTP
V
CCTP
(MIN)
t
RPD2
V
CC
t
F
RESET Slews With V
CC
FIGURE 4-4:
Timing Diagram –
Power Down (TC1274).
RESET
t
RPD1
V
OL
FIGURE 4-2:
Timing Diagram – Power
Down (TC1272/TC1273).
2003 Microchip Technology Inc.
DS21382B-page 5
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