© 2007 Microchip Technology Inc.
DS21382C-page 1
TC1272/TC1273/TC1274
Features
• Precision V
CC
Monitor for 5.0V Systems
• 100 ms Minimum RESET, RESET Output
Duration
• Output Valid to V
CC
= 1.2V
• V
CC
Transient Immunity
• Small 3-Pin SOT-23 Package
• No External Components
Applications
• Computers
• Embedded Systems
• Battery-Powered Equipment
• Critical µP Power Supply Monitoring
Package Type
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 µs of V
CC
falling through the reset voltage threshold. RESET is
maintained active for a minimum of 100 ms 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-23
package.
The TC1272/TC1273/TC1274 devices are optimized to
reject fast transient glitches on the V
CC
line.
Typical Application Circuit
V
CC
RESET
**(RESET)
GND
TC1272
TC1273
TC1274
1
2
3
**( ) is for TC1274
3-Pin SOT-23
TC1272
V
CC
V
CC
V
CC
RESET
RESET
Input
GND
GND
Processor
1
2
3
3-Pin Reset Monitors for 5V Systems
Obsolete Device
TC1272/TC1273/TC1274
DS21382C-page 2
© 2007 Microchip Technology Inc.
1.0
ELECTRICAL
CHARACTERISTICS
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-23 (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
† 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.
DC CHARACTERISTICS
Electrical Specifications: Unless otherwise noted, T
A
= -40°C to +85°C. Typical values are at T
A
= +25°C.
Parameters
Sym
Min
Typ
Max
Units
Conditions
Supply Voltage
TC1272, TC1273
V
CC
1.2
—
5.5
V
Note 1
TC1274
V
CC
1.8
—
5.5
V
Output Voltage @ 0-500 µA
V
OH
V
CC
– 0.5V V
CC
– 0.1V
—
V
TC1272, TC1274 (Note 1)
Output Current @ 2.4 Volts
V
CC
= 5V TC1272
I
OH
—
10
—
mA
Note 2
V
CC
= 4V TC1274
I
OH
—
8
—
mA
Output Current @ 0.4 Volts
I
OL
+10
30
—
mA
Note 2, Note 5
Operating Current
V
CC
< 5.5V: TC1272, TC1274
I
CC
—
17
40
µA
Note 3
V
CCTP
< V
CC
< 5.5V: TC1273
I
CC
—
17
40
µA
Note 3
V
CC
< V
CCTP
: TC1273
I
CC
—
700
1200
µA
Note 3
V
CC
Trip Point (TC1272/3/4-5) V
CCTP-5
4.50
4.62
4.75
V
Note 1
V
CC
Trip Point (TC1272/3/4-10) V
CCTP-10
4.25
4.37
4.49
V
Note 1
V
CC
Trip Point (TC1272/3/4-15) V
CCTP-15
4.00
4.12
4.24
V
Note 1
Output Capacitance
C
OUT
—
9
—
pF
Internal Pull-Up Resistor
R
P
3
6
9
k
Ω
AC Electrical Characteristics: T
A
= -40°C to +85°C unless otherwise noted. Typical values are at T
A
= +25°C.
RESET Active Time
t
RST
100
200
300
ms
V
CC
Detect to RESET
TC1272, TC1273
t
RPD1
—
20
50
µs
V
CC(LOW)
= 1V, Figure 4-2
V
CC
Detect to RESET - TC1274
t
RPD2
—
20
50
µs
V
CC(LOW)
= 1V, Figure 4-4
V
CC
Slew Rate
(V
CCTP
(MAX) to V
CCTP
(MIN))
t
F
300
—
—
µs
Figure 4-2, Figure 4-4
V
CC
Slew Rate
(V
CCTP
(MIN) to V
CCTP
(MAX))
t
R
0
—
—
ns
Figure 4-1, Figure 4-3
V
CC
Detect to RESET
TC1272, TC1273
t
RPU1
100
200
300
ms
Note 4, Figure 4-1
V
CC
Detect to RESET - TC1274
t
RPU2
100
200
300
ms
Note 4, Figure 4-3
Note 1: All voltages referenced to ground.
2: Measured with V
CC
≥ 2.7 volts.
3: Measured with RESET output open for TC1272/TC1273; measured with RESET output open for TC1274.
4: t
R
= 5 µs.
5: A 1 k
Ω external resistor may be required in some applications for proper operation of the microprocessor reset control
circuit when using the TC1273.
© 2007 Microchip Technology Inc.
DS21382C-page 3
TC1272/TC1273/TC1274
2.0
TYPICAL PERFORMANCE CURVES
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
FIGURE 2-1:
V
CC
Detect to Reset
(RESET).
FIGURE 2-2:
Reset Delays vs.
Comparator Overdrive.
Note:
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.
V
CC
SLEW RATE (V/
μ
sec)
V
CC
TO RESET DELAY (
μ
sec)
10000
1000
1
10
100
1000
10000
100000
100000
100
10
V
OD
= 1V
V
OD
= 2V
V
OD
= 200mV
V
OD
= 100mV
V
OD
= 20mV
T
A
= 25
°
C
V
CC
TO RESET DELAY (
μ
sec)
300
200
100
0
0
1
2
3
4
5
COMPARATOR OVERDRIVE (V)
T
A
= 25
°
C
TC1272/TC1273/TC1274
DS21382C-page 4
© 2007 Microchip Technology Inc.
3.0
PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 3-1.
TABLE 3-1:
PIN FUNCTION TABLES
3.1
RESET Output (RESET)
The RESET output remains low while V
CC
is below the
reset voltage threshold, and for 200 ms (100 ms
minimum) 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.
3.2
RESET Output (RESET)
The RESET output remains high while V
CC
is below the
reset voltage threshold, and for 200 ms (100 ms
minimum) after V
CC
rises above reset threshold. The
output stage of the TC1274 is complimentary.
Pin No.
Symbol
Function
1
RESET
RESET Output (TC1272 and TC1273)
1
RESET
RESET Output (TC1274)
2
V
CC
Supply voltage (1.2V to 5.5V TC1272 and TC1273; 1.8V to 5.5V TC1274)
3
GND
Ground
© 2007 Microchip Technology Inc.
DS21382C-page 5
TC1272/TC1273/TC1274
4.0
APPLICATIONS INFORMATION
4.1
Operation – Power Monitor
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.
FIGURE 4-1:
Timing Diagram – Power Up
(TC1272/TC1273).
FIGURE 4-2:
Timing Diagram – Power
Down (TC1272/TC1273).
FIGURE 4-3:
Timing Diagram – Power Up
(TC1274).
FIGURE 4-4:
Timing Diagram –
Power Down (TC1274).
V
CCTP
(MAX)
V
CCTP
(MIN)
t
R
V
CCTP
V
CC
RESET
t
RPU1
V
OH
V
CC
RESET
V
CCTP
(MAX)
V
CCTP
V
CCTP
(MIN)
V
OL
t
RPD1
t
F
t
R
t
RPU2
V
OL
V
CCTP
V
CC
RESET
V
CCTP
(MAX)
V
CCTP
(MIN)
t
F
t
RPD2
V
CC
V
CCTP
(MAX)
V
OH
RESET
V
CCTP
V
CCTP
(MIN)
RESET Slews With V
CC
TC1272/TC1273/TC1274
DS21382C-page 6
© 2007 Microchip Technology Inc.
4.2
V
CC
Transient Rejection
The TC1272/TC1273/TC1274 provides accurate V
CC
monitoring and reset timing during power-up, power-
down and brownout/sag conditions, and rejects
negative-going transients (glitches) on the power
supply line. Figure 4-5 shows the maximum transient
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 brownout or power-down condition.
Transient immunity can be improved by adding a
capacitor in close proximity to the V
CC
pin of the
TC1272/TC1273/TC1274.
4.3
RESET Signal Integrity During
Power-Down
The TC1272 RESET output is valid to V
CC
= 1.2V.
Below this voltage the output becomes an "open
circuit" and does not sink current. This means CMOS
logic inputs to the
μP will be floating at an undeter-
mined voltage. Most digital systems are completely
shut down well above this voltage. However, in situa-
tions where RESET must be maintained valid to
V
CC
= 0V, a pull-down resistor must be connected from
RESET to ground to discharge stray capacitances and
hold the output low (Figure 4-6). This resistor value,
though not critical, should be chosen such that it does
not appreciably load RESET under normal operation
(100 k
Ω will be suitable for most applications). Simi-
larly, a pull-up resistor to V
CC
is required for the
TC1274 to ensure a valid high RESET for V
CC
below
1.8V.
FIGURE 4-5:
Maximum Transient
Duration vs. Overdrive For Glitch Rejection At
+25°C.
FIGURE 4-6:
Ensuring Reset Valid To
V
cc
= 0V.
RESET COMPARATOR OVERDRIVE,
[V
CCTP
-V
CC
] (mV)
500
300
200
400
100
0
1
10
100
1000
MA
X
IMUM TRA
N
SIENT D
URA
T
ION (µsec)
T
A
= +25°C
V
TH
Duration
Overdrive
V
CC
TC1272/3/4
TC1272
V
CC
V
CC
R
1
100 k
Ω
RESET
GND
© 2007 Microchip Technology Inc.
DS21382C-page 7
TC1272/TC1273/TC1274
5.0
PACKAGING INFORMATION
5.1
Package Marking Information
Reset V
CC
Threshold (V)
TC1272
Code
TC1273
Code
TC1274
Code
4.62
X1
Y1
Z1
4.37
X2
Y2
Z2
4.12
X3
Y3
Z3
1
2
3
3-Pin SOT-23
1 2 3 4
represents part number code +
temperature range and voltage
&
1
2
represents year and quarter code
3
represents lot ID number
4
TC1272/TC1273/TC1274
DS21382C-page 8
© 2007 Microchip Technology Inc.
3-Lead Plastic Small Outline Transistor (TT or NB) [SOT-23]
Notes:
1. Dimensions D and E1 do not include mold flash or protrusions. Mold flash or protrusions shall not exceed 0.25 mm per side.
2. Dimensioning and tolerancing per ASME Y14.5M.
BSC: Basic Dimension. Theoretically exact value shown without tolerances.
Note:
For the most current package drawings, please see the Microchip Packaging Specification located at
http://www.microchip.com/packaging
Units
MILLIMETERS
Dimension Limits
MIN
NOM
MAX
Number of Pins
N
3
Lead Pitch
e
0.95 BSC
Outside Lead Pitch
e1
1.90 BSC
Overall Height
A
0.89
–
1.12
Molded Package Thickness
A2
0.79
0.95
1.02
Standoff
A1
0.01
–
0.10
Overall Width
E
2.10
–
2.64
Molded Package Width
E1
1.16
1.30
1.40
Overall Length
D
2.67
2.90
3.05
Foot Length
L
0.13
0.50
0.60
Foot Angle
φ
0°
–
10°
Lead Thickness
c
0.08
–
0.20
Lead Width
b
0.30
–
0.54
b
N
E
E1
2
1
e
e1
D
A
A1
A2
c
L
φ
Microchip Technology Drawing C04-104B
© 2007 Microchip Technology Inc.
DS21382C-page9
TC1272/TC1273/TC1274
PRODUCT IDENTIFICATION SYSTEM
To order or obtain information, e.g., on pricing or delivery, refer to the factory or the listed sales office.
PART NO.
X
/XX
Package
Temperature
Range
Device
Device:
TC1272: 3-Pin Reset Monitor - Complementary
TC1273: 3-Pin Reset Monitor - Open-Drain
TC1274: 3-Pin Reset Monitor - Complementary
Reset V
CC
Threshold Voltage
5
= 4.62V
10
= 4.37V
15
= 4.12V
Temperature Range:
E
= -40°C to +85°C
Package:
NB = Plastic Small Outline Transistor (SOT-23), 3-lead
Examples:
a)
TC1272-10ENBTR: 4.37V Reset
b)
TC1272-15ENBTR: 4.12V Reset
c)
TC1272-5ENBTR:
4.62V Reset
a)
TC1273-10ENBTR: 4.37V Reset
b)
TC1273-15ENBTR: 4.12V Reset
c)
TC1273-5ENBTR:
4.62V Reset
a)
TC1274-10ENBTR: 4.37V Reset
b)
TC1274-15ENBTR: 4.12V Reset
c)
TC1274-5ENBTR:
4.62V Reset
XX
Reset V
CC
Threshold
TC1272/TC1273/TC1274
DS21382C-page 10
© 2007 Microchip Technology Inc.
NOTES: