ADP1655 データシートの表示（PDF） - Analog Devices

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ADP1655

Dual LED Flash Driver with I2C-Compatible Interface

Analog Devices 

FEATURES

Ultracompact solution

Small 2 mm × 1.5 mm 12-ball WLCSP package

Tiny, low profile 2.2 μH power inductor

LED current source for local LED grounding and low EMI

Synchronous 2 MHz PWM boost convertor, no external diode

High efficiency: 88% peak

Reduces high levels of input battery current during flash

Limits battery current drain in torch mode

I2C programmable

Currents up to 400 mA in flash mode for two LEDs

Currents up to 500 mA in flash mode for one LED with

5% accuracy

Currents up to 160 mA in torch mode with 10% accuracy

Peak inductor current limit

Flash timer

Control

I2C-compatible control registers

External STROBE pin

External direct TORCH pin

TX_MASK input to prevent high input battery current levels

Safety

Thermal overload protection

Flash timeout

Inductor fault detection

Output overvoltage

Short circuit protection

Soft start reduces inrush input current

APPLICATIONS

Camera-enabled cellular phones and smart phones

Digital still cameras, camcorders, and PDAs

GENERAL DESCRIPTION

The ADP1655 is a very compact, highly efficient, dual white

LED flash driver for high resolution camera phones, which

improves picture and video quality in low light environments.

The device integrates a 2 MHz synchronous inductive boost

convertor, an I2C-compatible interface and a 500 mA current

source. The high switching frequency enables the use of a tiny,

low profile 2.2 μH power inductor, and the current source

permits LED cathode grounding for thermally enhanced,

low EMI and compact layouts.

The efficiency is high over the entire battery voltage range to

maximize the input power to LED power conversion and

Dual LED Flash Driver with

I2C-Compatible Interface

ADP1655

FUNCTIONAL BLOCK DIAGRAM

INPUT VOLTAGE = 2.5V TO 5.5V

2.2µH

10µF

STROBE VIN SW

TORCH

VOUT

ADP1655

SCL/EN1

LED_OUT

SDA/EN2

TX_MASK

I2C/EN SGND PGND

10µF

Figure 1.

3mm

Li-ION +

L1

INDUCTOR

C1

PGND Li-ION +

C2

LED

ANODE

6.5mm

Figure 2. PCB Layout

DIGITAL

INPUT/

OUTPUT

minimize battery current draw during flash events. In addition,

a Tx-mask input permits the flash LED current to reduce quickly

and, therefore, the battery current reduces quickly, during a

GSM power amplifier current burst.

The I2C-compatible interface enables the programmability

of timers, currents, and status bit readback for operation

monitoring and safety control.

The ADP1655 comes in a compact 12-ball 0.5 mm pitch

WLCSP package and is specified over the full −40°C to

+125°C junction temperature range.

Rev. 0

Information furnished by Analog Devices is believed to be accurate and reliable. However, no

responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other

rights of third parties that may result from its use. Specifications subject to change without notice. No

license is granted by implication or otherwise under any patent or patent rights of Analog Devices.

Trademarks and registered trademarks are the property of their respective owners.

One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.

Tel: 781.329.4700

www.analog.com

Fax: 781.461.3113

©2009 Analog Devices, Inc. All rights reserved.

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