NSC LM2704MFX-ADJ, LM2704MF-ADJ, LM2704EV, LM2704-ADJMDC Datasheet

LM2704
Micropower Step-up DC/DC Converter with 550mA Peak
Current Limit

General Description

The LM2704 is a micropower step-up DC/DC in a small
5-lead SOT-23 package. A current limited, fixed off-time
control scheme conserves operating current resulting in high
efficiency over a wide range of load conditions. The 21V
switch allows for output voltages as high as 20V. The low
400ns off-time permits the use of tiny, low profile inductors
and capacitors to minimize footprint and cost in space­conscious portable applications. The LM2704 is ideal for
LCD panels requiring low current and high efficiency as well
as white LED applications for cellular phone back-lighting.
The LM2704 can drive up to 8 white LEDs from a single
Li-Ion battery.

Features

n 550mA, 0.7Ω, internal switch
n Uses small surface mount components
n Adjustable output voltage up to 20V
n 2.2V to 7V input range
n Input undervoltage lockout
n 0.01µA shutdown current
n Small 5-Lead SOT-23 package

Applications

n LCD Bias Supplies
n White LED Back-Lighting
n Handheld Devices
n Digital Cameras
n Portable Applications

Typical Application Circuit

20031501

FIGURE 1. Typical 20V Application

April 2003

LM2704 Micropower Step-up DC/DC Converter with 550mA Peak Current Limit

© 2003 National Semiconductor Corporation DS200315 www.national.com

Connection Diagram

Top View

20031502

SOT23-5

T

Jmax

= 125˚C, θJA= 220˚C/W (Note 2)

Ordering Information

Order Number Package Type NSC Package Drawing Top Mark Supplied As

LM2704MF-ADJ SOT23-5 MA05B S28B 1000 Units, Tape and Reel

LM2704MFX-ADJ SOT23-5 MA05B S28B 3000 Units, Tape and Reel

Pin Description/Functions

Pin Name Function

1 SW Power Switch input.

2 GND Ground.

3 FB Output voltage feedback input.

4 SHDN

Shutdown control input, active low.

5V

IN

Analog and Power input.

SW(Pin 1): Switch Pin. This is the drain of the internal
NMOS power switch. Minimize the metal trace area con­nected to this pin to minimize EMI.

GND(Pin 2): Ground Pin. Tie directly to ground plane.
FB(Pin 3): Feedback Pin. Set the output voltage by selecting

values for R1 and R2 using:

Connect the ground of the feedback network to an AGND
plane which should be tied directly to the GND pin.

SHDN(Pin 4): Shutdown Pin. The shutdown pin is an active
low control. Tie this pin above 1.1V to enable the device. Tie
this pin below 0.3V to turn off the device.

V

IN

(Pin 5): Input Supply Pin. Bypass this pin with a capacitor

as close to the device as possible.

LM2704

www.national.com 2

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

IN

7.5V

SW Voltage 21V

FB Voltage 2V

SHDN Voltage

7.5V

Maximum Junction Temp. T

J

(Note 2)

150˚C

Lead Temperature
(Soldering 10 sec.) 300˚C

Vapor Phase
(60 sec.) 215˚C

Infrared
(15 sec.) 220˚C

ESD Ratings (Note 3)

Human Body Model
Machine Model (Note 4)

2kV

200V

Operating Conditions

Junction Temperature
(Note 5) −40˚C to +125˚C

Supply Voltage 2.2V to 7V

SW Voltage Max. 20.5V

Electrical Characteristics (Note 5)

Specifications in standard type face are for TJ= 25˚C and those in boldface type apply over the full Operating Temperature
Range (T

J

= −40˚C to +125˚C). Unless otherwise specified. VIN=2.2V.

Symbol Parameter Conditions

Min

(Note 5)

Typ

(Note 6)

Max

(Note 5)

Units

I

Q

Device Disabled FB = 1.3V 40 70

µADevice Enabled FB = 1.2V 235 300

Shutdown SHDN = 0V

0.01 2.5

V

FB

Feedback Trip Point 1.189 1.237 1.269 V

I

CL

Switch Current Limit 490

420

550 610

620

mA

I

B

FB Pin Bias Current FB = 1.23V (Note 7) 30 120 nA

V

IN

Input Voltage Range 2.2 7.0 V

R

DSON

Switch R

DSON

0.7 1.6 Ω

T

OFF

Switch Off Time 400 ns

I

SD

SHDN Pin Current SHDN = VIN,TJ= 25˚C 080

nASHDN = V

IN,TJ

= 125˚C 15

SHDN = GND

0

I

L

Switch Leakage Current VSW= 20V 0.05 5 µA

UVP Input Undervoltage Lockout ON/OFF Threshold 1.8 V

V

FB

Hysteresis

Feedback Hysteresis 8

mV

SHDN
Threshold

SHDN low

0.7 0.3

V

SHDN High

1.1 0.7

θ

JA

Thermal Resistance 220 ˚C/W

Note 1: Absolute maximum ratings are limits beyond which damage to the device may occur. Operating Ratings are conditions for which the device is intended to
be functional, but device parameter specifications may not be guaranteed. For guaranteed specifications and test conditions, see the Electrical Characteristics.

Note 2: The maximum allowable power dissipation is a function of the maximum junction temperature, T

J

(MAX), the junction-to-ambient thermal resistance, θJA,

and the ambient temperature, T

A

. See the Electrical Characteristics table for the thermal resistance. The maximum allowable power dissipation at any ambient

temperature is calculated using: P

D

(MAX) = (T

J(MAX)−TA

)/θJA. Exceeding the maximum allowable power dissipation will cause excessive die temperature.

Note 3: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. The machine model is a 200 pF capacitor discharged
directly into each pin.

Note 4: ESD susceptibility using the machine model is 150V for SW pin.

Note 5: All limits guaranteed at room temperature (standard typeface) and at temperature extremes (bold typeface). All room temperature limits are 100%

production tested or guaranteed through statistical analysis. All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality
Control (SQC) methods. All limits are used to calculate Average Outgoing Quality Level (AOQL).

Note 6: Typical numbers are at 25˚C and represent the most likely norm.

Note 7: Feedback current flows into the pin.

LM2704

www.national.com3

Typical Performance Characteristics

Enable Current vs V

IN

(Part Switching)

Disable Current vs V

IN

(Part Not Switching)

20031505 20031506

Efficiency vs Load Current Efficiency vs Load Current

20031510

20031511

LM2704

www.national.com 4