Microchip Technology TC1279-5ENB, TC1279-15ENB, TC1279-10ENB, TC1278-5ENB, TC1278-15ENB Datasheet
...
TC1278/TC1279
3-Pin Reset Monitors for 5V Systems
Features
• PrecisionVCCMonitor for 5.0V System Supplies
• 250msec Minimum RESET Output Duration
• Output Validto V
TransientImmunity
•V
CC
CC
=1.2V
• Small 3-Pin SOT-23BPackage
• No External Components
Applications
• Computers
• Embedded Systems
• Battery Powered Equipment
• Critical µP Power Supply Monitoring
Device Selection Table
Part
Number
TC1278-xENB Open Drain 3-Pin SOT-23B -40°C to +85°C
TC1279-xENB Open Drain 3-Pin SOT-23B -40°C to +85°C
NOTE: “x” denotes a suffix for VCCthreshold (see table below).
Order Package
Suffix Reset VCCThreshold (V)
5 4.625
10 4.375
15 4.125
Temp.
Range
Package Type
General Description
The TC1278/TC1279 are cost-effective system supervisorcircuitsdesigned to monitor V
indigitalsystems
CC
and provide a reset signal to the host processor when
necessary. No external components are required.
The reset output is driven active within 5µsec of V
CC
falling through the reset voltage threshold. RESET is
maintainedactive for a minimum of 250msec after V
CC
rises above the r eset threshold. The TC1278 has an
active-high RESET output while the TC1279 has an
active-low RESET
output, and both devices have an
open drain output stage. The output is valid down to
V
= 1.2V.Both devices are available ina 3-Pin SOT-
CC
23B package.
Typical Operating Circuit
V
CC
2
V
CC
RESET
V
CC
1
Processor
RESET
Input
TC1279
GND GND
3
3-Pin SOT-23B
RESET
NOTE: 3-Pin SOT-23B is equivalent to JEDEC TO-236
2002 Microchip TechnologyInc. DS21384B-page 1
1
TC1278-xENB
TC1279-xENB
V
2
CC
GND
3
TC1278/TC1279
1.0 ELECTRICAL
CHARACTERISTICS
*Stresses above those listed under "Absolute Maximum
Ratings" 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
Absolute Maximum Ratings*
Supply Voltage (VCCto GND)..............................+6.0V
, RESET...........................-0.3V to (VCC+0.3V)
RESET
Input Current, V
...............................................20mA
CC
operation sections of the specifications is not implied.
Exposure to Absolute Maximum Rating conditions for
extended periods may affectdevice reliability.
Output Current, RESET.......................................20mA
Power Dissipation (T
≤ 70°C)
A
3-Pin SOT-23B (derate 4mW/°C above +70°C)
.................................................................230mW
Operating Temperature Range.............-40°C to +85°C
StorageTemperature Range..............-65°C to +150°C
TC1278/TC1279 ELE CTRI CAL SPECIFICATIONS
Recommended DC Operating Conditions: TA= -40°C to +85°C unless otherwise noted. Typical values are at TA=+25°C.
Symbol Parameter Min Typ Max Units Device Test Conditions
V
CC
DC Electrical Characteristics: T
Symbol Parameter Min Typ Max Units Test Conditions
V
OL
I
OL
I
CC1
I
CC2
V
CCTP-5VCC
V
CCTP-10VCC
V
CCTP-15VCC
C
OUT
R
P
AC Electrical Characteristics: T
Symbol Parameter Min Typ Max Units Test Conditions
t
RST
t
RPD1
t
RPD2
t
F
t
R
t
RPU1
t
RPU2
Note 1: All voltages referenced to ground.
Supply Voltage 1.2 — 5.5 V Note 1
= -40°C to +85°C unless otherwise noted. Typical values are at TA=+25°C.
A
Low Level @ RESET
RESET
— — 0.4 V TC1278
TC1279
Note 1
Output Current @ 0.4 Volts +8 — — mA Note 2
Operating Current —
—
Operating Current —
—
0.9
—
—
0.9
2.040mAµATC1278
TC1279
40
2.0µAmA
TC1278
TC1279
VCC>V
VCC>V
VCC<V
VCC<V
CCTP(MAX)
CCTP(MAX)
CCTP(MIN)
CCTP(MIN)
Trip Point (TC1278/9-5) 4.50 4.625 4.74 V Note 1
Trip Point (TC1278/9-10) 4.25 4.375 4.49 V Note 1
Trip Point (TC1278/9-15) 4.00 4.125 4.24 V Note 1
Output Capacitance — 9 — pF
Internal Pull-Up Resistor 3 6 9 kΩ
= -40°C to +85°C unless otherwise noted. Typical values are at TA=+25°C.
A
RESET Active Time 250 350 450 msec
VCCDetect to RESET —25µsec TC1279 Figure 3-2
VCCDetect to RESET — 2 5 µsec TC1278 Figure 3-4
VCCSlew Rate
300 — — µsec Figure3-2, Figure 3-4
(4.75V-4.00V)
VCCSlew Rate
0 — — nsec Figure3-1,Figure 3-3
(4.00V-4.75V)
VCCDetect to RESET 250 350 450 msec TC1279 Figure 3-1
VCCDetect to RESET 250 350 450 msec TC1278 Figure 3-3
2: A1kΩ external resistor may be required in some applications for proper operation of the microprocessor reset control circuit when using
the TC1279. V
CC
=1.8V.
DS21384B-page 2
2002 Microchip TechnologyInc.
2.0 PIN DESCRIPTIONS
The descriptions of the pins are listed in Table 2-1.
TABLE 2-1: PIN FUNCTION TABLE
TC1278/TC1279
Pin No.
(3-Pin SOT-23B)
1 RESET
1 RESET (TC1278) RESET output remains high while V
2V
3 GND Ground.
Symbol Description
(TC1279) RESET outputremains low while VCCis below the reset voltage threshold,andfor
350msec (250msec min.) after V
TC1279 is open drain.
350msec (250msec min.) after V
TC1278 is open drain.
CC
Supply voltage (1.2V to 5.5V).
rises aboveresetthreshold. The outputstage of the
CC
is below the reset voltage threshold,andfor
CC
rises aboveresetthreshold. The outputstage of the
CC
2002 Microchip TechnologyInc. DS21384B-page 3
TC1278/TC1279
3.0 APPLICATIONS INFORMATION
3.1 Operation – P ow er Monitor
The TC1278/TC1279 provide the function of detecting
out-of-tolerance power supply conditions and war ning
a processor-based system of impending power failure.
When V
signal is asserted. On power-up, RESET is kept active
for approximately 350msec after the power supply has
reached the selected tolerance. This al lows the power
supply and microprocessor to stabilize before RESET
is released.
FIGURE 3-1: Timing Diagram –
V
CC
RESET
is detected as out-of-tolerance, the RESET
CC
Power Up (TC1279)
t
R
4.75V
V
4.00V
CCTP
t
RPU
1
V
OH
FIGURE 3-3: Timing Diagram –
Power Up (TC1278)
t
R
V
CCTP(MAX)
V
CCTP
t
RPU2
V
CC
RESET
V
CCTP(MIN)
FIGURE 3-4: Timing Diagram –
Power Down (TC1278)
t
F
V
CC
4.74V
V
CCTP
4.00V
t
RPD2
V
OL
FIGURE 3-2: Timing Diagram –
Power Dow n (TC1279)
t
F
4.00V
t
RPD1
V
OL
VCC
RESET
4.75V
V
CCTP
RESET
V
OH
RESET SLEWS WITH V
CC
DS21384B-page 4
2002 Microchip TechnologyInc.
Loading...