National Semiconductor LM3722 Technical data
LM3722/LM3723/LM3724
5-Pin Microprocessor Reset Circuits
LM3722/LM3723/LM3724 5-Pin Microprocessor Reset Circuits
June 2001
General Description
The LM3722/LM3723/LM3724 microprocessor supervisory
circuits monitor the power supplies in microprocessor and
digital systems. They provide a reset to the microprocessor
during power-up, power-down, brown-out conditions, and
manual reset.
The LM3722/LM3723/LM3724 asserts a reset signal whenever the supply decreases below the factory-programmed
reset threshold for at least 100 ms. The reset signal remains
asserted for 190 ms after V
The LM3722 has anactive-low RESET push-pull output. The
LM3723 has an active-high RESET push-pull output. The
LM3724 has an active-low open-drain RESET output.
Three standard reset voltage options are available, suitable
for monitoring 5V, 3.3V, and 2.5V supply voltages. Additional
reset voltages are also available; contact National Semiconductor for details.
With a low supply current of only 6µA, the
LM3722/LM3723/LM3724 are ideal foruse in portable equipment. The LM3722/LM3723/LM3724 are available in the
5-pin SOT23 package.
rises above the threshold.
CC
Typical Application Circuit
Features
n Precise monitoring of 2.5V, 3.3V, and 5V supply
voltages
n Fully specified over temperature
Industrial: −40˚C to +85˚C
Extended: −40˚C to +125˚C
n 100 ms minimum Power-On Reset pulse width, 190 ms
typical:
Active-Low RESET Output (LM3722)
Active-High RESET Output (LM3723)
Active-Low RESET Open Drain Output (LM3724)
n Guaranteed RESET Output valid for VCC≥ 1V
n Low Supply Current, 6µA typical
n Power supply transient immunity
n Compatible with MAX811/812 applications
Applications
n Microprocessor Systems
n Computers
n Controllers
n Intelligent Instruments
n Portable/Battery-Powered Equipment
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Connection Diagram
SOT23-5
*
( ) are for LM3723
© 2001 National Semiconductor Corporation DS200144 www.national.com
20014402
Ordering Information
Industrial Temperature Range (−40˚C to +85˚C):
Reset
Threshold (V)
4.63 LM3722IM5-4.63 LM3722IM5X-4.63 R43B
LM3722/LM3723/LM3724
2.32 LM3722IM5-2.32 LM3722IM5X-2.32 R34B
Reset
Threshold (V)
4.63 LM3723IM5-4.63 LM3723IM5X-4.63 R13B
2.32 LM3723IM5-2.32 LM3723IM5X-2.32 R46B
Reset
Threshold (V)
4.63 LM3724IM5-4.63 LM3724IM5X-4.63 R55B
2.32 LM3724IM5-2.32 LM3724IM5X-2.32 R50B
LM3722 Supplied as
1000 units, tape & reel
LM3723 Supplied as
1000 units, tape & reel
LM3724 Supplied as
1000 units, tape & reel
LM3722 Supplied as
3000 units, tape & reel
LM3723 Supplied as
3000 units, tape & reel
LM3724 Supplied as
3000 units, tape & reel
Package
Top Mark
Package
Top Mark
Package
Top Mark
Package
Type
SOT23-5 MF05A3.08 LM3722IM5-3.08 LM3722IM5X-3.08 R41B
Package
Type
SOT23-5 MF05A3.08 LM3723IM5-3.08 LM3723IM5X-3.08 R11B
Package
Type
SOT23-5 MF05A3.08 LM3724IM5-3.08 LM3724IM5X-3.08 R53B
Extended Temperature Range (−40˚C to +125˚C):
Reset
Threshold (V)
4.63 LM3722EM5-4.63 LM3722EM5X-4.63 R56B
2.32 LM3722EM5-2.32 LM3722EM5X-2.32 R58B
Reset
Threshold (V)
4.63 LM3723EM5-4.63 LM3723EM5X-4.63 R59B
2.32 LM3723EM5-2.32 LM3723EM5X-2.32 R61B
Reset
Threshold (V)
4.63 LM3724EM5-4.63 LM3724EM5X-4.63 R62B
2.32 LM3724EM5-2.32 LM3724EM5X-2.32 R64B
Custom voltages and improved accuracies are available, subject to minimum orders. Contact your local National Semiconductor Sales Office for information.
LM3722 Supplied as
1000 units, tape & reel
LM3723 Supplied as
1000 units, tape & reel
LM3724 Supplied as
1000 units, tape & reel
LM3722 Supplied as
3000 units, tape & reel
LM3723 Supplied as
3000 units, tape & reel
LM3724 Supplied as
3000 units, tape & reel
Package
Top Mark
Package
Top Mark
Package
Top Mark
Package
Type
SOT23-5 MF05A3.08 LM3722EM5-3.08 LM3722EM5X-3.08 R57B
Package
Type
SOT23-5 MF05A3.08 LM3723EM5-3.08 LM3723EM5X-3.08 R60
Package
Type
SOT23-5 MF05A3.08 LM3724EM5-3.08 LM3724EM5X-3.08 R63B
NSC Package
NSC Package
NSC Package
NSC Package
NSC Package
NSC Package
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Pin Description
PIN NAME FUNCTION
1 GND Ground reference
2 GND Ground reference, device substrate, connect to ground.
RESET
3
LM3722/LM3724
RESET
LM3723
4MR
Active-low output. RESET remains low while V
voltage, and for 190 ms after VCCrises above the reset threshold voltage.
Active-high output. RESET remains high while V
for 190 ms after V
rises above the reset threshold.
CC
Active-low input. Reset is asserted whenever this pin is pulled low and remains
asserted for 190 ms after the MR pin goes high. May be left open.
5VCCSupply Voltage (+5V, +3.3V, or +2.5V, nominal)
Block Diagram
LM3722/LM3723/LM3724 Block Diagram
is below the reset threshold
CC
is below the reset threshold, and
CC
LM3722/LM3723/LM3724
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Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.
V
,MR −0.3V to 6.0V
CC
RESET, RESET
Input Current, V
Output Current, RESET,
LM3722/LM3723/LM3724
RESET Pin
Pin 20mA
CC
−0.3V to (VCC+ 0.3V)
20mA
Continuous Power Dissipation (T
SOT-23 (Note 3) 320mW
Operating Temperature Range
Industrial: −40˚C to +85˚C
Extended: −40˚C to +125˚C
Maximum Junction Temperature 125˚C
Storage Temperature Range −65˚C to +160˚C
Lead Temperature
(soldering, 10sec) +300˚C
= +70˚C)
A
ESD Rating (Note 2) 2kV
Electrical Characteristics
Typical values are at TA= +25˚C. Limits with standard typeface are for TA= +25˚C, and limits in boldface type apply for the
operating temperature range (−40˚C to +85˚C) for LM372_IM5X, and (−40˚C to +125˚C) for LM372_EM5X, unless otherwise
noted. (Note 4)
Symbol Parameter Conditions Min Typ Max Units
V
I
V
V
Tempco
t
t
t
t
V
V
V
V
V
V
V
VCCRange 1.0 5.5 V
CC
LM372 _ -4.63 V
LM372 _ -3.08 V
LM372 _ -2.32 V
CC
Supply Current
= 0A)
(I
LOAD
LM372 _ -4.63
Reset Threshold
TH
LM372 _ -2.32
Reset Threshold
TH
Temperature Coefficient
VCCto Reset Delay (Note 5) VCC=VTHto (VTH− 100mV) 20 µs
RD
Reset Active Timeout Period 100 190 560 ms
RP
MR Minimum Pulse Width 10 µs
MR
MR to Reset Propagation
MD
Delay
MR Glitch Immunity (Note 6)
IH
IL
MR Input Threshold
IH
IL
V
CC
V
CC
-2.32
>
V
>
V
, LM372_ -4.63
TH(MAX)
, LM372_ -3.08, LM372_
TH(MAX)
= 5.5V 8 15 µA
CC
= 3.6V 7 10
CC
= 2.5V 6 10
CC
4.54
4.63 4.72
4.50
3.03
3.08 3.14
3.00
2.27
2.32 2.37
2.25
30 ppm/˚C
2µs
100 ns
2.3
0.7 V
CC
MR Pull-Up Resistance 22 kΩ
RESET Output Voltage Low
OL
(LM3722)
RESET Output Voltage High
OH
(LM3722)
V
CC=VTH
min, I
(LM3722-2.32/3.08)
CC=VTH
min, I
(LM3722-4.63)
>
V
1V, I
CC
V
CC
>
VTHmax, I
SINK
(LM3722-2.32/3.08)
>
VTHmax, I
V
CC
= 1.2mA,
SINK
= 3.2mA,
SINK
= 50µA 0.3
SOURCE
SOURCE
= 500µA,
= 800µA,
0.8V
CC
VCC−1.5
(LM3722-4.63)
RESET Output Voltage Low
OL
(LM3723)
V
CC=VTH
max, I
(LM3723 -2.32/3.08)
V
CC=VTH
max, I
SINK
SINK
= 1.2mA
= 3.2mA
(LM3723 -4.63)
4.75
3.15
2.40
0.8
0.25 V
0.3
0.4
0.3
0.4
VLM372 _ -3.08
V
CC
VV
V
V
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