3 MHz, 600 mA, Low Quiescent Current

Buck with 300 mA LDO Regulator

Data Sheet

ADP2140

Rev. B

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FEATURES

Input voltage range: 2.3 V to 5.5 V

LDO input (VIN2) 1.65 V to 5.5 V

Buck output voltage range: 1.0 V to 3.3 V

LDO output voltage range: 0.8 V to 3.3 V

Buck output current: 600 mA

LDO output current: 300 mA

LDO quiescent current: 22 μA with zero load

Buck quiescent current: 20 μA in PSM mode

Low shutdown current: <0.3 μA

Low LDO dropout 110 mV @ 300 mA load

High LDO PSRR

Initial accuracy: ±1%

Current-limit and thermal overload protection

Power-good indicator

Optional enable sequencing

10-lead 0.75 mm × 3 mm × 3 mm LFCSP package

APPLICATIONS

Mobile phones

Personal media players

Digital camera and audio devices

Portable and battery-powered equipment

TYPICAL APPLICATION CIRCUITS

VIN1

PGND

PG

SW

EN1

AGND

EN2

PG

EN1

EN2

FB

VOUT2

10

9

8

7

6

VIN2

1

2

3

4

5

ADP2140

100kΩ

+

10µF

+

1µF

10µF

1µH

VIN1

PGND

PG

SW

EN1

AGND

EN2

PG

EN1

EN2

FB

VOUT2

10

9

8

7

6

VIN2

1

2

3

4

5

ADP2140

100kΩ

+

10µF

+

1µF

10µF

1µH

Figure 2. ADP2140 with LDO Connected to Buck Output

GENERAL DESCRIPTION

The ADP2140 includes a high efficiency, low quiescent 600 mA

stepdown dc-to-dc converter and a 300 mA LDO packaged in a

small 10-lead 3 mm × 3 mm LFCSP. The total solution requires

only four tiny external components.

The buck regulator uses a proprietary high speed current-

mode, constant frequency, pulse-width modulation (PWM)

control scheme for excellent stability and transient response. To

ensure the longest battery life in portable applications, the

ADP2140 has a power saving variable frequency mode to reduce

switching frequency under light loads.

The LDO is a low quiescent current, low dropout linear regulator

1.65 V. The low input voltage minimum allows the LDO to be

powered from the output of the buck regulator increasing effi-

ciency and reducing power dissipation. The ADP2140 runs from

input voltages of 2.3 V to 5.5 V allowing single Li+/Li− polymer

cell, multiple alkaline/NiMH cell, PCMCIA, and other standard

power sources.

ADP2140 includes a power-good pin, soft start, and internal

compensation. Numerous power sequencing options are user-

selectable through two enable inputs. In autosequencing mode,

the highest voltage output enables on the rising edge of EN1.

During logic controlled shutdown, the input disconnects from

the output and draws less than 300 nA from the input source.

Other key features include: undervoltage lockout to prevent deep

battery discharge, soft start to prevent input current overshoot

at startup, and both short-circuit protection and thermal overload

protection circuits to prevent damage in adverse conditions.

When the ADP2140 is used with two 0603 capacitors, one 0402

capacitor, one 0402 resistor, and one 0805 chip inductor, the

footprint solution to meet a variety of portable applications.