600 mA/1000 mA, 2.5 MHz Buck-Boost

DC-to-DC Converter

Preliminary Technical Data

ADP2503/ADP2504

FEATURES

1 mm height profile

Compact PCB footprint

Seamless transition between modes

38 μA typical quiescent current

2.5 MHz operation enables 1 μH inductor

Input voltage: 2.3 V to 5.5 V

Fixed output voltage: 2.8 V to 5.0 V

600 mA (ADP2503) and 1000 mA (ADP2504) output options

Boost converter configuration with load disconnect

Sync pin with three different modes:

Power save mode (PSM) for improved light load efficiency

Forced fixed frequency operation mode

Synchronization with external clock

Internal compensation

Soft start

Enable/shutdown logic input

Overtemperature protection

Short-circuit protection

Undervoltage lockout protection

Small 10-lead 3 mm × 3 mm LFCSP/QFN package

APPLICATIONS

Wireless handsets

Digital cameras/portable audio players

Miniature hard disk power supplies

USB powered devices

GENERAL DESCRIPTION

The ADP2503/ADP2504 are high efficiency, low quiescent

current step-up/step-down dc-to-dc converters that can operate

at input voltages above, below, or equal to the regulated output

voltage. The power switches and synchronous rectifiers are

internal to minimize external part count. At high load currents,

the ADP2503/ADP2504 use a current-mode, fixed frequency

PWM control scheme for optimal stability and transient response.

To ensure the longest battery life in portable applications, the

ADP2503/ADP2504 have an optional power save mode that

reduces the switching frequency under light load conditions.

For wireless and other low noise applications where variable

frequency power save mode may cause interference, the logic

control input sync forces fixed frequency PWM operation

under all load conditions.

The ADP2503/ADP2504 can run from input voltages between

2.3 V and 5.5 V, allowing single lithium or lithium polymer cell,

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

standard power sources. The ADP2503/ADP2504 have fixed

output options ranging from 2.8 V to 5 V. Compensation is

internal to minimize the number of external components.

During logic-controlled shutdown, the input is disconnected

from the output and draws less than 1 μA from the input source.

Operating as a boost converter, the ADP2503/ADP2504 feature

a true load disconnect function that isolates the load from the

power source. Other key features include under voltage lockout

to prevent deep battery discharge and soft start to prevent input

current overshoot at startup.

TYPICAL APPLICATION CIRCUIT

1.0µH

SW1

PVIN

2.3V TO 5.5V

2.8V TO 5V

22µF

10µF

ADP2503

VIN

VOUT

SW2

FB

SYNC

EN

OFF

ON

PGND

AGND

Figure 1. Application Circuit

Rev. PrB

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