Compact, 600 mA, 3 MHz,

Step-Down DC-to-DC Converter

ADP2108

Rev. A

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FEATURES

Peak efficiency: 95%

3 MHz fixed frequency operation

Typical quiescent current: 18 μA

Maximum load current: 600 mA

Input voltage: 2.3 V to 5.5 V

Uses tiny multilayer inductors and capacitors

Current mode architecture for fast load and line

transient response

100% duty cycle low dropout mode

Internal synchronous rectifier

Internal compensation

Internal soft start

Current overload protection

Thermal shutdown protection

Shutdown supply current: 0.2 μA

5-ball WLCSP

APPLICATIONS

PDAs and palmtop computers

Wireless handsets

Digital audio, portable media players

Digital cameras, GPS navigation units

GENERAL DESCRIPTION

The ADP2108 is a high efficiency, low quiescent current step-

down dc-to-dc converter in an ultrasmall 5-ball WLCSP

package. The total solution requires only three tiny external

components. It uses a proprietary, high speed current mode,

constant frequency PWM control scheme for excellent stability

and transient response. To ensure the longest battery life in

portable applications, the ADP2108 has a power save mode that

reduces the switching frequency under light load conditions.

The ADP2108 runs on input voltages of 2.3 V to 5.5 V, which

allows for single lithium or lithium polymer cell, multiple alkaline

or NiMH cell, PCMCIA, USB, and other standard power sources.

The maximum load current of 600 mA is achievable across the

input voltage range.

The ADP2108 is available in fixed output voltages of 3.3 V, 3.0 V,

2.5 V, 2.3 V, 1.82 V, 1.8 V, 1.5 V, 1.3 V, 1.2 V, 1.1 V, and 1.0 V. All

versions include an internal power switch and synchronous rect-

ifier for minimal external part count and high efficiency. The

ADP2108 has an internal soft start and is internally compensated.

During logic controlled shutdown, the input is disconnected

from the output and the ADP2108 draws less than 1 μA from

the input source.

Other key features include undervoltage lockout to prevent deep

battery discharge and soft start to prevent input current over-

shoot at startup. The ADP2108 is available in a 5-ball WLCSP.

TYPICAL APPLICATIONS CIRCUIT

1.0V TO 3.3V

10µF

1µH

ON

OFF

GND

4.7µF

VIN

SW

FB

EN

2.3V TO 5.5V

ADP2108

Figure 1.