Compact, 800 mA, 3 MHz,

Simple DVS, Buck Regulator

ADP2147

Rev. 0

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FEATURES

Input voltage: 2.3 V to 5.5 V

Peak efficiency: 95%

3 MHz fixed frequency operation

Low quiescent current: 23 μA

Ultralow shutdown current: 0.2 μA (typical)

VSEL pin for simple dynamic voltage scaling (DVS)

100% duty cycle low dropout mode

Internal synchronous rectifier, compensation, and soft start

Current overload and thermal shutdown protection

Small, 6-ball, 1 mm × 1.5 mm WLCSP package

APPLICATIONS

PDAs and palmtop computers

Wireless handsets

Digital audio portable media players

Digital cameras, GPS navigation units

Low power portable medical equipment

GENERAL DESCRIPTION

The ADP2147 is a high efficiency, low quiescent current, step-

down (buck) dc-to-dc regulator with an output voltage that can

be switched between two different settings under the control of

a select pin. The total solution requires only three tiny external

components.

The buck regulator automatically switches operating modes,

depending on the load current level, to maximize efficiency. At

high output loads, the buck regulator operates in PWM mode.

When the load current falls below a predefined threshold, the

regulator operates in power save mode (PSM), improving the

light-load efficiency.

The ADP2147 runs on input voltages of 2.3 V to 5.5 V, which

allows for single lithium or lithium polymer cells, multiple

alkaline or NiMH cells, PCMCIA, USB, and other standard

power sources. The maximum load current of 800 mA is

achievable across the input voltage range.

The ADP2147 is available with fixed output voltages from 0.8 V

to 3.3 V. All versions include an internal power switch and

synchronous rectifier for minimal external part count and high

efficiency. The ADP2147 has an internal soft start and is

internally compensated. During logic controlled shutdown, the

input is disconnected from the output, and the ADP2147 draws

less than 0.2 μA (typical) from the power source.

Other key features include undervoltage lockout to prevent deep

battery discharge and soft start to prevent input current over-

shoot at startup. The ADP2147 is available in a 6-ball WLCSP.

TYPICAL APPLICATIONS CIRCUIT

ON

OFF

VIN

SW

EN

VSEL

GND

VOUT

ADP2147

4.7µF

4.7µF

2.3V TO 5.5V

1.0µH

Figure 1.