Fairchild Semiconductor FM1233EC Datasheet
©2003 Fairchild Semiconductor Corporation
1
www.fairchildsemi.com
February 2003
FM1233E 3-Pin µC Supervisor Circuit
FM1233E Rev. D
FM1233E
3-Pin µC Supervisor Circuit
General Description
The FM1233E is a supervisor circuit that monitors a microprocessor 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 voltage reference and comparator. When V
CC
falls to the threshold
voltage, a RESET pulse is issued, holding the output in the
active state. When power rises above V
TH
, the reset remains for
approximately 250 ms to allow the system clock and other circuits to stabilize. The reset output of FM1233E is of open-drain
active low type.
Features
■
Precision monitoring of 3.3V and lower voltage
microprocessor systems
■
V
TH
values of 2.88V, 2.72V
■
Automatic restart of microprocessor after power failure
■
140ms (min) power-on RESET
delay (typ.: 256ms)
■
Internal 5k Ω pull-up resistor
■
Other reset choices available: 32 to 128ms
■
Operating Temperature -40°C to +105°C
■
SOT23-3 package
Typical Operating Circuit
Connection Diagram
SOT23-3 Package
1
FM1233E
Controller
2
3
V
CC
GND
RESET
GND
V
CC
RESET
1
FM1233E
2
3
FM1233E 3-Pin µC Supervisor Circuit
2
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FM1233E Rev. D
Absolute Maximum Ratings
Voltage on any pin relative to GND
V
CC
-0.3V to +6.0V
RESET
-0.3V to (V
CC
+ 0.3V)
Input Current 20mA
Output Current (RESET
) 20mA
Continuous Power Dissipation (T
A
= 70°C)
SOT23 (derate 4mW above 70°C) 300mW
Operating Temperature Range -40°C to +105°C
Storage Temperature Range -65°C to +150°C
Lead Temperature (soldering, 10s) +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 (V
CC
= 3.3V; TA = -40°C to +105°C unless otherwise
noted) (Note 1)
Note 1: Testing at production is done at 25°C only. Limits over temperature are guaranteed by design.
Parameter Symbol Conditions Min Typ Max Units
Operating V oltage V
CC
1.2 3.3 5.5 V
Supply Current I
CC
V
CC
< 3.3V 3 6 µA
Reset Threshold V
TH
FM1233EC 2.70 2.88 2.97 V
Reset Threshold V
TH
FM1233ED 2.58 2.72 2.86 V
Reset Output Voltage V
OL
FM1233E I
SINK
= 5mA
V
CC
= V
TH
(min)
0.4 V
Reset Timeout Period t
RST
FM1233E 140 256 560 ms
FM1233E 3-Pin µC Supervisor Circuit
3
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FM1233E Rev. D
Typical Operating Characteristics
Supply Current Vs. Temperature
Power up Reset Timeout Vs. Temperature
0
2
4
6
8
10
0
2
4
6
8
10
+110C+25C-55C
Temperature (C)
I
CC
(µA)
VCC = 3.3V
100
200
300
400
500
600
100
200
300
400
500
600
+105C+25C-40C
Temperature (C)
Power up Reset timeout (ms)
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