National Semiconductor LM2751 Technical data

April 2005

LM2751
Regulated 2X, 1.5X Switched Capacitor White LED Driver

LM2751 Regulated 2X, 1.5X Switched Capacitor White LED Driver

General Description

The LM2751 is a constant frequency switched capacitor
charge pump with regulated output voltage options of 4.5V,
and 5.0V. Over the input voltage range of 2.8V to 5.5V the
LM2751 provides up to 150mA of output current and requires
only four low-cost ceramic capacitors.

The LM2751 provides excellent efficiency without the use of
an inductor by operating the charge pump in a gain of 3/2 or

2. The proper gain for maintaining regulation is chosen so
that efficiency is maximized over the input voltage range.

LM2751 uses constant frequency pre-regulation to minimize
conducted noise on the input and provide a predictable
switching frequency. The switching frequency is program­mable to 725kHz, 300kHz, 37kHz, or 9.5kHz.

LM2751 is available in a 10-pin Leadless Leadframe No­Pullback Package: LLP-10.

Typical Application Circuit

Features

n Regulated Output Options: 4.5V, 5.0V
n Output Voltage Regulated within 3%
n Peak Efficiency Over 90%
n 150mA (4.5V) or 80mA (5.0V) Output Current Capability
n Input Voltage Range: 2.8V to 5.5V
n Low Input and Output Voltage Ripple

<

n

1µA Typical Shutdown Current

n Small Solution Size - NO INDUCTOR
n Programmable 725kHz, 300kHz, 37kHz, or 9.5kHz

Switching Frequencies

n 10-pin LLP No-Pullback Package: 3mm x 3mm x 0.8mm

Applications

n White LED Display Backlights
n White LED Keypad Backlights
n General Purpose 2x, 1.5x Regulated Charge Pump

20112101

LM2751 2x/1.5x Efficiency vs.

2x Charge Pump Effciency

20112128

© 2005 National Semiconductor Corporation DS201121 www.national.com

Connection Diagram

LM2751

Pin Descriptions

#

Pin

1V

2C

3V

4 CS0 Frequency Select Input 0.

5 CS1 Frequency Select Input 1.

6 EN Enable Pin Logic Input.

7C

8 GND Ground.

9C

10 C

10-pin Leadless Leadframe Package (LLP-10) No Pullback

3mm x 3mm x 0.8mm

NS Package Number SDA10A

Name Description

OUT

1+

IN

2−

1−

2+

Pre-Regulated Output.

Flying Capacitor C1 Connection.

Input Supply Range: 2.8V to 5.5V.

Flying Capacitor C2 Connection.

Flying Capacitor C1 Connection.

Flying Capacitor C2 Connection.

20112102

Ordering Information

Version Voltage Option Order Number Package Marking Supplied As Tape and

A 5.0V LM2751SD-A XXXXX

A 5.0V LM2751SDX-A 4500 Units

B 4.5V LM2751SD-B XXXXX

B 4.5V LM2751SDX-B 4500 Units

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Reel

1000 Units

YYYYY = L145B

1000 Units

YYYYY = L146B

LM2751

Absolute Maximum Ratings (Notes 1, 2)

If Military/Aerospace specified devices are required,
please contact the National Semiconductor Sales Office/
Distributors for availability and specifications.

Pin −0.3V to 6.0V

V

IN

EN, CS0, CS1 Pins −0.3V to (V

Continuous Power Dissipation
(Note 3) Internally Limited

Junction Temperature
(T

J-MAX-ABS

) 150˚C

Storage Temperature Range −65˚C to 150˚C

Maximum Lead Temperature 265˚C

(Soldering, 10sec.)

ESD Rating (Note 4)

Human-body model:
Machine model:

+0.3)

IN

w/ 6.0V max

2kV

200V

Operating Ratings (Notes 1, 2)

Input Voltage Range 2.8V to 5.5V

EN, CS0, CS1 Input Voltage Range 0V to V

Junction Temperature (TJ) Range -40˚C to 115˚C

Ambient Temperature (T

(Note 5)

Recommended Maximum Load Current

Version Freq. = 725kHz 150mA

B Freq. = 300kHz 120mA

Version Freq. = 725kHz 80mA

A Freq. = 300kHz 60mA

) Range -40˚C to 85˚C

A

Freq. = 37kHz 40mA

Freq. = 9.5kHz 10mA

Freq. = 37kHz 16mA

Freq. = 9.5kHz 4mA

Thermal Properties

Junction-to-Ambient Thermal
Resistance, LLP-10 55˚C/W

Package (θ

) (Note 6)

JA

Electrical Characteristics (Notes 2, 7)

Limits in standard typeface are for TA=25oC. Limits in boldface type apply over the full operating ambient temperature range
(-40˚C ≤ T
= 3.6V, V(EN) = V

Symbol Parameter Conditions Min Typ Max Units

V

OUT

V

R

I

Q

I

SD

E Efficiency I

≤ +85˚C) . Unless otherwise noted, specifications apply to the LM2751 Typical Application Circuit (pg. 1) with: V

A

Output Voltage Version A, 2.8V ≤ VIN≤ 5.5V,

Output Ripple 2.8V ≤ VIN≤ 5.5V

Quiescent Current Freq. = 9.5kHz, I

CS0=CS1=VIN,C1=C2= 1.0µF, CIN=C

IN,

Freq. = 300kHz, 725kHz, T

= 0 to 60mA

I

OUT

Version A, 2.8V ≤ V
Freq. = 300kHz, I
Freq. = 725kHz, I

Version B, 2.8V ≤ V

IN

OUT

OUT

IN

Freq. = 300kHz, 725kHz, T

= 0 to 120mA

I

OUT

Version B, 2.8V ≤ V
Freq. = 300kHz, I
Freq. = 725kHz, I

= 60mA

I

OUT

Freq. = 37kHz, I

Freq. = 300kHz, I

Freq. = 725kHz, I

IN

OUT

OUT

OUT

= 0mA, VIN= 3.7V 450 640

OUT

OUT

OUT

= 2.2µF (Note 8).

OUT

= 25˚C

A

≤ 5.5V,
= 0 to 60mA

4.850
(-3%)

4.775

(-4.5%)

5.0 5.150
(+3%)

5.225

(+4.5%)

= 0 to 80mA

≤ 5.5V,

= 25˚C

A

≤ 5.5V,
= 0 to 120mA

4.343

(-3.5%)

4.275
(-5%)

4.5 4.658

(+3.5%)

4.725

(+5%)

= 0 to 150mA

8mV

= 0mA, VIN= 3.7V 425 600 µA

= 0mA, VIN= 3.7V 700 900

= 0mA, VIN= 3.7V 1000 1500

Shutdown Supply Current V(EN) = 0V 0.77 1.3 µA

V(EN) = 0V, T

= 80mA (Version A, 5.0V)

OUT

= 85˚C 1.0

A

92 %

Freq. = 300kHz, 725kHz

= 150mA (Version B, 4.5V)

I

OUT

83

Freq. = 300kHz, 725kHz

IN

IN

V

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Electrical Characteristics (Notes 2, 7) (Continued)

Limits in standard typeface are for TA=25oC. Limits in boldface type apply over the full operating ambient temperature range

LM2751

(-40˚C ≤ T
= 3.6V, V(EN) = V

Symbol Parameter Conditions Min Typ Max Units

fsw Switching Frequency CS0 = High, CS1 = Low

V

IH

V

IL

I

IH

I

IL

V

G

I

SC

t

ON

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the component may occur. Operating Ratings are conditions under which operation of
the device is guaranteed. Operating Ratings do not imply guaranteed performance limits. For guaranteed performance limits and associated test conditions, see the
Electrical Characteristics tables.

Note 2: All voltages are with respect to the potential at the GND pin.

Note 3: Internal thermal shutdown circuitry protects the device from permanent damage. Thermal shutdown engages at T

T

=140˚C (typ.).

J

Note 4: The Human body model is a 100 pF capacitor discharged through a 1.5kΩ resistor into each pin. The machine model is a 200pF capacitor discharged
directly into each pin. MIL-STD-883 3015.7

Note 5: In applications where high power dissipation and/or poor package thermal resistance is present, the maximum ambient temperature may have to be
derated. Maximum ambient temperature (T
dissipation of the device in the application (P
following equation: T

Note 6: Junction-to-ambient thermal resistance (θ
standard JESD51-7. The test board is a 4 layer FR-4 board measuring 102mm x 76mm x 1.6mm witha2x1array of thermal vias. The ground plane on the board
is 50mm x 50mm. Thickness of copper layers are 36µm/18µm /18µm/36µm (1.5oz/1oz/1oz/1.5oz). Ambient temperature in simulation is 22
dissipation is 1W.

The value of θ
conditions. In applications where high maximum power dissipation exists (high V
information on these topics, please refer to Application Note 1187: Leadless Leadframe Package (LLP) and the Power Efficiency and Power Dissipation
section of this datasheet.

Note 7: Min and Max limits are guaranteed by design, test, or statistical analysis. Typical numbers are not guaranteed, but represent the most likely norm.

Note 8: C

Note 9: EN Logic Input High Current (I

Note 10: Turn-on time is measured from when the EN signal is pulled high until the output voltage on V

≤ +85˚C) . Unless otherwise noted, specifications apply to the LM2751 Typical Application Circuit (pg. 1) with: V

A

Logic Input High Input Pins: EN, CS0, CS1

Logic Input Low Input Pins: EN, CS0, CS1

Logic Input High Current Input Pins: CS0, CS1

CS0=CS1=VIN,C1=C2= 1.0µF, CIN=C

IN,

2.8V ≤ V

IN

≤ 5.5V

CS0 = Low, CS1 = Low

2.8V ≤ VIN≤ 5.5V

CS0 = Low, CS1 = High

2.8V ≤ VIN≤ 5.5V

CS0 = High, CS1 = High

2.8V ≤ V

2.8V ≤ V

2.8V ≤ V

IN

IN

IN

≤ 5.5V

≤ 5.5V

≤ 5.5V

= 2.2µF (Note 8).

OUT

6.7

(−30%)

26

(−30%)

210

(−30%)

508

(−30%)

1.00 V

9.5 12.3

(+30%)

37 48

(+30%)

300 390

(+30%)

725 942

(+30%)

IN

0 .30 V

10 nA

V(CSx) = 1.8V

Input Pin: EN

2µA

V(EN) = 1.8V(Note 9)

Logic Input Low Current Input Pins: EN, CS0, CS1

10 nA

V(EN, CSx) = 0V

Gain Transition Voltage
(Version A, B)

1.5X to 2X 3.50 V

2X to 1.5X 3.58

Hysteresis 40 80 150 mV

Short Circuit Output

V

= 0V 250 mA

OUT

Current

V

Turn-On Time

OUT

300 µs

(Note 10)

=150˚C (typ.) and disengages at

J

) is dependent on the maximum operation junction temperature (T

A-MAX

), and the junction-to ambient thermal resistance of the part/package in the application (θJA), as given by the

D-MAX

A-MAX=TJ-MAX-OP

of the LM2751 in LLP-10 could fall in a range as wide as 50oC/W to 150oC/W (if not wider), depending on PWB material, layout, and environmental

JA

IN,COUT,C1

, and C2: Low-ESR Surface-Mount Ceramic Capacitors (MLCCs) used in setting electrical characteristics.

-(θJAxP

)isduetoa1MΩ(typ.) pull-down resistor connected internally between the EN pin and GND.

IH

).

D-MAX

) is taken from a thermal modeling result, performed under the conditions and guidelines set forth in the JEDEC

JA

, high I

IN

), special care must be paid to thermal dissipation issues. For more

OUT

crosses 90% of its final value.

OUT

=115oC), the maximum power

J-MAX-OP

o

C, still air. Power

IN

kHz

V

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