NSC LM2623AMM, LM2623AMDC, LM2623ALDX, LM2623MMX, LM2623LDX Datasheet

LM2623
General Purpose, Gated Oscillator Based, DC/DC Boost
Converter

General Description

The LM2623 is a high efficiency, general purpose, step-up
DC-DC switching regulator for battery-powered and low in­put voltage systems. It accepts an input voltage between .8
and 14 volts and converts it into a regulated output voltage
between 1.24 and 14 volts. Efficiencies up to 90% are
achievable with the LM2623.

In order to adapt to a number of applications, the LM2623
allows the designer to vary the output voltage, the operating
frequency (300kHz to 2 MHz) and duty cycle (17% to 90%)
to optimize the part’s performance. The selected values can
be fixed or can vary with battery voltage or input to output
voltage ratio. The LM2623 uses a very simple, on/off regu­lation mode to produce good efficiency and stable operation
over a wide operating range. It normally regulates by skip­ping switching cycles when it reaches the regulation limit
(Pulse Frequency Modulation).

Note: Please read the "Non-Linear Effect" and "Choosing
The Correct C3 Capacitor" sub-sections of the Design Pro­cedure section of this data sheet, so that any challenges with
designing with this part can be taken into account before a
board design/layout is finalized.

For Alternative Solutions, See Also: LM2700, LM2622,
LM2731, LM2733, and LM2621.

Features

n Good Efficiency Over a Very Wide Load Range
n Very Low Output Voltage Ripple
n Small, Mini-SO-8 Package (Half the Footprint of

Standard 8 pin SO Package)

n 1.09 mm Package Height
n Up to 2 MHz Switching Frequency
n .8V to 14V Operating Voltage
n 1.1V Start-up Voltage
n 1.24V - 14V Adjustable Output Voltage
n Up to 2A Load Current at low Output Voltages
n 0.17Ω Internal MOSFET
n Up to 90% Regulator Efficiency
n 80 µA Typical Operating Current (into V

DD

pin of supply)

n

<

2.5µA Guaranteed Supply Current In Shutdown

n 4mm x 4mm Thermally Enhanced LLP Package Option

Applications

n Cameras, Pagers and Cell Phones
n PDAs,Palmtop Computers, GPS devices
n White LED Drive, TFT or Scanned LCDs
n Flash Memory Programming
n Hand-Held Instruments
n 1, 2, 3 or 4 Cell Alkaline Systems
n 1, 2 or 3 Cell Lithium-ion Systems

Typical Application Circuit

20038801

July 2003

LM2623 General Purpose, Gated Oscillator Based, DC/DC Boost Converter

© 2003 National Semiconductor Corporation DS200388 www.national.com

Connection Diagram

LLP Package

20038802

Top View

Mini SO-8 (MM) Package

20038818

Top View

Ordering Information

Order Number Package Type

NSC Package

Drawing

Package

Marking

Supplied As

LM2623MMX Mini SO-8 MUA08A S46B 3000 Units on Tape and Reel

LM2623AMMX Mini SO-8 MUA08A S46A 3000 Units on Tape and Reel

LM2623AMM Mini SO-8 MUA08A S46A 1000 Units on Tape and Reel

LM2623MM Mini SO-8 MUA08A S46B 1000 Units on Tape and Reel

LM2623LDX LLP-14 LDA14A 2623AB 4500 Units on Tape and Reel

LM2623ALDX LLP-14 LDA14A 2623A 4500 Units on Tape and Reel

LM2623LD LLP-14 LDA14A 2623AB 1000 Units on Tape and Reel

LM2623ALD LLP-14 LDA14A 2623A 1000 Units on Tape and Reel

LM2623

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Pin Description

LLP-14 Pin MSOP-8 Pin Name Function

1 NC No Connect

2, 3 1 PGND

Power Ground (LLP Pins2&3must be shorted
together).

4 2 EN Active-Low Shutdown Input

5 3 FREQ Frequency Adjust. An external resistor connected

between this pin and a voltage source sets the
switching frequency of the LM2623.

6 4 FB Output Voltage Feedback

7 NC No Connect

8 NC No connect

9 5 SGND Signal Ground

10 6 V

DD

Power Supply for Internal Circuitry

11 7 BOOT

Bootstrap Supply for the Gate Drive of Internal
MOSFET Power Switch

12, 13 8 SW

Drain of the Internal MOSFET Power Switch. (LLP Pins
12&13must be shorted together).

14 NC No Connect

DAP DAP

To be soldered to board for enhanced thermal
dissipation. To be electrically isolated/floating.

LM2623

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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.

SW Pin Voltage −0.5 V to 14.5V

BOOT, V

DD

, EN and FB Pins −0.5V to 10V

FREQ Pin 100µA

T

Jmax

(Note 2) 150˚C

Storage Temperature Range −65˚C to +150˚C

Lead Temp. (Soldering, 5 sec) 260˚C

Power Dissipation (T

A

=25˚C)

(Note 2)

500mW

ESD Rating (Note 3) 2kV

Operating Conditions (Note 1)

V

DD

Pin 3V to 5V

FB, EN Pins 0 to V

DD

BOOT Pin 0 to 10V

Ambient Temperature (T

A

) −40˚C to +85˚C

Electrical Characteristics

Limits in standard typeface are for TJ= 25˚C, and limits in boldface type apply over the full operating temperature range of

−40˚C to +85˚C. Unless otherwise specified: V

DD=VOUT

= 3.3V.

Symbol Parameter Condition Typ Min Max Units

V

DD_ST

Start-Up Supply Voltage 25˚C I

LOAD

= 0mA (Note 4) 1.1 V

V

IN_OP

Minimum Operating Supply
Voltage (once started)

I

LOAD

= 0mA 0.65 .8 V

V

FB

FB Pin Voltage 1.24 1.2028 1.2772 V

V

OUT_MAX

Maximum Output Voltage 14 V

η Efficiency V

IN

= 3.6V; V

OUT

= 5V; I

LOAD

=

500mA

87

%

V

IN

= 2.5V; V

OUT

= 3.3V; I

LOAD

= 200mA

87

D Switch Duty Cycle 17 %

I

DD

Operating Quiescent Current
(Note 5)

FB Pin>1.3V; EN Pin at V

DD

80 110 µA

I

SD

Shutdown Quiescent Current
(Note 6)

VDD, BOOT and SW Pins at

5.0V; EN Pin

<

200mV

0.01 2.5 µA

I

CL

Switch Peak Current Limit LM2623A 2. 85 2.2 A

I

C

Switch Peak Current Limit LM2623 1.2 A

R

DS_ON

MOSFET Switch On
Resistance

0.17 0.26 Ω

θ

JA

Thermal Resistance MM Package, Junction to

Ambient(Note 2)

240 ˚C/W

θ

JA

Thermal Resistance LLP Package, Junction to

Ambient(Notes 2, 8)

40 ˚C/W

θ

JA

Thermal Resistance LLP Package, Junction to

Ambient(Notes 2, 9)

56 ˚C/W

Enable Section

V

EN_LO

EN Pin Voltage Low (Note 7) 0.15V

DD

V

V

EN_HI

EN Pin Voltage High (Note 7) 0.7V

DD

V

Note 1: Absolute maximum ratings indicate limits beyond which damage to the device may occur. Electrical specifications do not apply when operating the device
outside of its rated operating conditions.

Note 2: The maximum power dissipation must be derated at elevated temperatures and is dictated by T

jmax

(maximum junction temperature), θJA(junction to

ambient thermal resistance), and T

A

(ambient temperature). The maximum allowable power dissipation at any temperature is P

dmax

=(T

jmax-TA

)/ θJAor the number

given in the Absolute Maximum Ratings, whichever is lower.

Note 3: The human body model is a 100 pF capacitor discharged through a 1.5 kΩ resistor into each pin. For Pin 8 (SW) the ESD rating is 1.0 kV.

Note 4: V

DD

tied to Boot and EN pins. Frequency pin tied to VDDthrough 121K resistor. V

DD_ST=VDD

when startu-up occurs. VINis VDD+ D1 voltage (usually

10-50 mv at start-up)

Note 5: This is the current into the V

DD

pin.

Note 6: This is the total current into pins V

DD

, BOOT, SW and FREQ.

Note 7: When the EN pin is below V

EN_LO

, the regulator is shut down; when it is above V

EN_HI

, the regulator is operating.

LM2623

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