基于ADP1650设计的1.5A LED闪光驱动技术

ADP1650是ADI 公司的集成了I2C兼容接口的1.5A LED闪光驱动器.器件集成了1.5MHz或3.0MHz同步电感升压转换器,I2C兼容接口和1500mA电流源.火炬模式电流高达200mA,效率大于90%(峰值),主要用在照相手机和智能手机以及数码相机,摄像机和PDA.本文介绍了ADP1650主要特性,应用电路以及ADP1650 评估板套件主要特性,详细电路图和材料清单.

1.5 A LED Flash Driver with I2C-Compatible Interface

The ADP1650 is a very compact, highly efficient, single white LED flash driver for high resolution camera phones that improves picture and video quality in low light environments. The device integrates a programmable 1.5 MHz or 3.0 MHz synchronous inductive boost converter, an I2C-compatible interface, and a 1500 mA current source. The high switching frequency enables the use of a tiny, 1 mm high, low cost, 1 μH power inductor, and the current source permits LED cathode grounding for thermally enhanced, low EMI, and compact layouts.

The LED driver maximizes efficiency over the entire battery voltage range to maximize the input-power-to-LED-power conversion and minimize battery current draw during flash events. A programmable dc battery current limit safely maximizes LED current for all LED VF and battery voltage conditions.

Two independent TxMASK inputs permit the flash LED current and battery current to reduce quickly during a power amplifier current burst. The I2C-compatible interface enables the pro-grammability of timers, currents, and status bit readback for operation monitoring and safety control.

The ADP1650 comes in a compact 12-ball, 0.5 mm pitch package and operates within specification over the full −40℃ to +125℃ junction temperature range.

ADP1650主要特性:

Ultracompact solution

Small, 2 mm × 1.5 mm, 12-ball WLCSP package

Smallest footprint, 1 mm height, 1 μH power inductor

LED current source for local LED grounding

Simplified routing to/from LED

Improved LED thermals

Synchronous 3 MHz PWM boost converter, no external diode

High efficiency: 90% peak

Reduces high levels of input battery current during flash

Limits battery current drain in torch mode

I2C programmable

Currents up to 1500 mA in flash mode for one LED with 7% accuracy over all conditions

Currents up to 200 mA in torch mode

Programmable dc battery current limit (4 settings)

Programmable flash timer up to 1600 ms

Low VBAT mode to reduce LED current automatically

4-bit ADC for LED VF, die/LED temperature readback

Control

I2C-compatible control registers

External STROBE and torch input pins

2 transmitter mask (TxMASK) inputs

Safety

Thermal overload protection

Inductor fault detection

LED short-/open-circuit protection

ADP1650应用:

Camera-enabled cellular phones and smart phones

Digital still cameras, camcorders, and PDAs


图1.ADP1650功能方框图

ADP1650 评估板

The evaluation system is composed of a motherboard, daughter- board and LED sub-board. The motherboard provides the I2C signals from the PC USB port and generates the I/O voltages and digital high and low signals for the daughterboard. For over-temperature measurement, the daughterboard can either be plugged directly into the motherboard or connected to the motherboard via a ribbon cable.

The motherboard features a 3.3 V regulator and 2.8 V/1.8 V regulators for VDDIO. The daughterboard contains jumpers and test points for easy evaluation of the flash driver IC.

The ADP1650-EVALZ kit includes:

Cables: power (red/black), USB, 2× current measurements

Samples: five ADP1650 devices, two FDSD3012 inductors

LED boards: OSRAM LUWF65N, LumiLEDs PWF-4


图2.ADP1650 评估板外形图

图3.ADP1650 评估板主板电路图

图4.ADP1650 评估板子板电路图

图5.ADP1650 LED插板电路图

图6.ADP1650- EVALZ电路图
评估板材料清单(BOM):