NSC LM3722E2.32MDC, LM3722EM5X-3.08, LM3722EM5-4.63, LM3722EM5-3.08, LM3722E4.63MWC Datasheet

LM3722/LM3723/LM3724
5-Pin Microprocessor Reset Circuits

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

CC

rises above the threshold.

The LM3722 has an active-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 for use in portable equip­ment. The LM3722/LM3723/LM3724 are available in the
5-pin SOT23 package.

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

Typical Application Circuit

20014401

20014437

Connection Diagram

SOT23-5

20014402

*

( ) are for LM3723

June 2001

LM3722/LM3723/LM3724 5-Pin Microprocessor Reset Circuits

© 2001 National Semiconductor Corporation DS200144 www.national.com

Ordering Information
Industrial Temperature Range (−40˚C to +85˚C):

Reset

Threshold (V)

LM3722 Supplied as

1000 units, tape & reel

LM3722 Supplied as

3000 units, tape & reel

Package

Top Mark

Package

Type

NSC Package

4.63 LM3722IM5-4.63 LM3722IM5X-4.63 R43B
SOT23-5 MF05A3.08 LM3722IM5-3.08 LM3722IM5X-3.08 R41B

2.32 LM3722IM5-2.32 LM3722IM5X-2.32 R34B

Reset

Threshold (V)

LM3723 Supplied as

1000 units, tape & reel

LM3723 Supplied as

3000 units, tape & reel

Package

Top Mark

Package

Type

NSC Package

4.63 LM3723IM5-4.63 LM3723IM5X-4.63 R13B
SOT23-5 MF05A3.08 LM3723IM5-3.08 LM3723IM5X-3.08 R11B

2.32 LM3723IM5-2.32 LM3723IM5X-2.32 R46B

Reset

Threshold (V)

LM3724 Supplied as

1000 units, tape & reel

LM3724 Supplied as

3000 units, tape & reel

Package

Top Mark

Package

Type

NSC Package

4.63 LM3724IM5-4.63 LM3724IM5X-4.63 R55B
SOT23-5 MF05A3.08 LM3724IM5-3.08 LM3724IM5X-3.08 R53B

2.32 LM3724IM5-2.32 LM3724IM5X-2.32 R50B

Extended Temperature Range (−40˚C to +125˚C):

Reset

Threshold (V)

LM3722 Supplied as

1000 units, tape & reel

LM3722 Supplied as

3000 units, tape & reel

Package

Top Mark

Package

Type

NSC Package

4.63 LM3722EM5-4.63 LM3722EM5X-4.63 R56B
SOT23-5 MF05A3.08 LM3722EM5-3.08 LM3722EM5X-3.08 R57B

2.32 LM3722EM5-2.32 LM3722EM5X-2.32 R58B

Reset

Threshold (V)

LM3723 Supplied as

1000 units, tape & reel

LM3723 Supplied as

3000 units, tape & reel

Package

Top Mark

Package

Type

NSC Package

4.63 LM3723EM5-4.63 LM3723EM5X-4.63 R59B
SOT23-5 MF05A3.08 LM3723EM5-3.08 LM3723EM5X-3.08 R60

2.32 LM3723EM5-2.32 LM3723EM5X-2.32 R61B

Reset

Threshold (V)

LM3724 Supplied as

1000 units, tape & reel

LM3724 Supplied as

3000 units, tape & reel

Package

Top Mark

Package

Type

NSC Package

4.63 LM3724EM5-4.63 LM3724EM5X-4.63 R62B
SOT23-5 MF05A3.08 LM3724EM5-3.08 LM3724EM5X-3.08 R63B

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/LM3723/LM3724

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Pin Description

PIN NAME FUNCTION

1 GND Ground reference
2 GND Ground reference, device substrate, connect to ground.

3

RESET

LM3722/LM3724

Active-low output. RESET remains low while V

CC

is below the reset threshold

voltage, and for 190 ms after VCCrises above the reset threshold voltage.

RESET

LM3723

Active-high output. RESET remains high while V

CC

is below the reset threshold, and

for 190 ms after V

CC

rises above the reset threshold.

4MR

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

20014435

LM3722/LM3723/LM3724

www.national.com3

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

CC

,MR −0.3V to 6.0V

RESET, RESET

−0.3V to (VCC+ 0.3V)

Input Current, V

CC

Pin 20mA

Output Current, RESET,
RESET Pin

20mA

ESD Rating (Note 2) 2kV

Continuous Power Dissipation (T

A

= +70˚C)

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

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

CC

VCCRange 1.0 5.5 V

I

CC

Supply Current
(I

LOAD

= 0A)

LM372 _ -4.63 V

CC

= 5.5V 8 15 µA

LM372 _ -3.08 V

CC

= 3.6V 7 10

LM372 _ -2.32 V

CC

= 2.5V 6 10

V

TH

Reset Threshold

LM372 _ -4.63

4.54

4.50

4.63 4.72

4.75

VLM372 _ -3.08

3.03

3.00

3.08 3.14

3.15

LM372 _ -2.32

2.27

2.25

2.32 2.37

2.40

V

TH

Tempco

Reset Threshold
Temperature Coefficient

30 ppm/˚C

t

RD

VCCto Reset Delay (Note 5) VCC=VTHto (VTH− 100mV) 20 µs

t

RP

Reset Active Timeout Period 100 190 560 ms

t

MR

MR Minimum Pulse Width 10 µs

t

MD

MR to Reset Propagation
Delay

2µs

MR Glitch Immunity (Note 6)

100 ns

V

IH

MR Input Threshold

V

CC

>

V

TH(MAX)

, LM372_ -4.63

2.3

V

V

IL

0.8

V

IH

V

CC

>

V

TH(MAX)

, LM372_ -3.08, LM372_

-2.32

0.7 V

CC

V

IL

0.25 V

CC

MR Pull-Up Resistance 22 kΩ

V

OL

RESET Output Voltage Low
(LM3722)

V

CC=VTH

min, I

SINK

= 1.2mA,

(LM3722-2.32/3.08)

0.3

VV

CC=VTH

min, I

SINK

= 3.2mA,

(LM3722-4.63)

0.4

V

CC

>

1V, I

SINK

= 50µA 0.3

V

OH

RESET Output Voltage High
(LM3722)

V

CC

>

VTHmax, I

SOURCE

= 500µA,

(LM3722-2.32/3.08)

0.8V

CC

V

V

CC

>

VTHmax, I

SOURCE

= 800µA,

(LM3722-4.63)

VCC−1.5

V

OL

RESET Output Voltage Low
(LM3723)

V

CC=VTH

max, I

SINK

= 1.2mA

(LM3723 -2.32/3.08)

0.3

V

V

CC=VTH

max, I

SINK

= 3.2mA

(LM3723 -4.63)

0.4

LM3722/LM3723/LM3724

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