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Fairchild Semiconductor |
February 2003
FM1233E
3-Pin µC Supervisor Circuit
General Description
The FM1233E is a supervisor circuit that monitors a micropro-
cessor power supply or other system voltage and issues a reset
pulse when a fault condition exists. Several different threshold
voltages are offered to accommodate 3V systems with different
tolerances.
The device features a precision temperature-compensated volt-
age reference and comparator. When VCC falls to the threshold
voltage, a RESET pulse is issued, holding the output in the
active state. When power rises above VTH, the reset remains for
approximately 250 ms to allow the system clock and other cir-
cuits to stabilize. The reset output of FM1233E is of open-drain
active low type.
Features
s Precision monitoring of 3.3V and lower voltage
microprocessor systems
s VTH values of 2.88V, 2.72V
s Automatic restart of microprocessor after power failure
s 140ms (min) power-on RESET delay (typ.: 256ms)
s Internal 5kΩ pull-up resistor
s Other reset choices available: 32 to 128ms
s Operating Temperature -40°C to +105°C
s SOT23-3 package
Typical Operating Circuit
VCC
GND
Connection Diagram
3
FM1233E
12
RESET
Controller
GND 1
FM1233E 3 VCC
RESET 2
SOT23-3 Package
©2003 Fairchild Semiconductor Corporation
FM1233E Rev. D
1
www.fairchildsemi.com
Absolute Maximum Ratings
Voltage on any pin relative to GND
VCC
RESET
Input Current
Output Current (RESET)
-0.3V to +6.0V
-0.3V to (VCC + 0.3V)
20mA
20mA
Continuous Power Dissipation (TA = 70°C)
SOT23 (derate 4mW above 70°C)
Operating Temperature Range
Storage Temperature Range
Lead Temperature (soldering, 10s)
300mW
-40°C to +105°C
-65°C to +150°C
+300°C
These are stress ratings only, and functional operation is not implied for these levels or beyond. Exposure to Absolute Maximum Rating
conditions for extended periods may affect device reliability.
Electrical Characteristics (VCC = 3.3V; TA = -40°C to +105°C unless otherwise
noted) (Note 1)
Parameter
Symbol
Conditions
Operating Voltage
Supply Current
Reset Threshold
Reset Threshold
Reset Output Voltage
Reset Timeout Period
VCC
ICC
VTH
VTH
VOL
tRST
VCC < 3.3V
FM1233EC
FM1233ED
FM1233E
FM1233E
ISINK = 5mA
VCC = VTH(min)
Note 1: Testing at production is done at 25°C only. Limits over temperature are guaranteed by design.
Min
1.2
2.70
2.58
140
Typ
3.3
3
2.88
2.72
256
Max
5.5
6
2.97
2.86
0.4
560
Units
V
µA
V
V
V
ms
FM1233E Rev. D
2 www.fairchildsemi.com
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