ADI ADP8860七路智能LED驱动方案

ADI公司的ADP8860是电荷泵带I2C接口的七路智能LED驱动器,具有可编程的背景光LED电荷泵和自动光电管控制.这种组合大大节省了能量.7个可编程驱动器中,6个驱动器的驱动电流30mA,1个驱动器的驱动电流为60mA,可编程最大限流(128级),工作电压从2.5 V 到5.5 V,广泛应用在移动显示器背景光,手机键盘背光,双路RGB背光,LED显示和小型显示器的背光.本文介绍了ADP8860的主要特性,方框图, 典型应用电路, 带键盘光控制的应用电路图以及评估系统中主板与子板的电路图和材料清单(BOM).

Charge Pump, 7-Channel Smart LED Driver with I2C Interface ADP8860

The ADP8860 combines a programmable backlight LED charge pump driver with automatic phototransistor control. This combination allows for significant power savings because it changes the current intensity in office and dark ambient light conditions. By performing this function automatically, it eliminates the need for a processor to monitor the phototransistor.

The light intensity thresholds are fully programmable via the I2C® interface. A second phototransistor input, with dedicated comparators, improves the ambient light detection levels for various user operating conditions.

The ADP8860 allows as many as six LEDs to be independently driven up to 30 mA (typical). A seventh LED can be driven to 60 mA (typical). All LEDs are programmable for minimum/max-imum current and fade in/out times via the I2C interface. These LEDs can also be combined into groups to reduce the processor instructions during fade in/out.

Driving this entire configuration is a two-capacitor charge pump with gains of 1×, 1.5×, and 2×. This setup is capable of driving a maximum IOUT of 240 mA from a supply of 2.5 V to 5.5 V. The device includes a variety of safety features including short-circuit, overvoltage, and overtemperature protection. These features allow easy implementation of a safe and robust design. Addi-tionally, input inrush currents are limited via an integrated soft start combined with controlled input-to-output isolation.

The ADP8860 is available in two package types, either a compact 2 mm × 2.4 mm × 0.6 mm WLCSP (wafer level chip scale package) or a small LFCSP (lead frame chip scale package).

ADP8860主要特性:

Charge pump with automatic gain selection of 1×, 1.5×, and 2× for maximum efficiency

Up to two built-in comparator inputs with programmable modes for ambient light sensing

Outdoor, office, and dark modes for maximum backlight power savings

7 independent and programmable LED drivers

6 drivers capable of 30 mA (typical)

1 driver capable of 60 mA (typical)

Programmable maximum current limit (128 levels)

Standby mode for <1 μA current consumption

16 programmable fade in and fade out times

0.1 sec to 5.5 sec

Choose from linear, square, or cubic rates

Fading override

I2C-compatible interface for all programming

Dedicated reset pin and built-in power-on reset (POR)

Short-circuit, overvoltage, and overtemperature protection

Internal soft start to limit inrush currents

Input-to-output isolation during faults or shutdown

Operation down to VIN = 2.5 V with undervoltage lockout (UVLO) at VIN = 2.0 V

Small wafer level chip scale package (WLCSP) or lead frame chip scale package (LFCSP)

ADP8860应用:

Mobile display backlighting

Mobile phone keypad backlighting

Dual RGB backlighting

LED indication

General backlighting of small format displays


图1.ADP8860方框图

图2.ADP8860典型应用电路


图3.具有键盘光控制的ADP8860应用电路图

ADP8860评估系统

The evaluation system is composed of a motherboard and a daughterboard. The motherboard provides the I2C® signals from the computer USB port and generates the I/O voltages and digital high and low signals for the daughterboard.

The motherboard features a 3.3 V regulator (VBOARD), a 3.7 V regulator (VBATT), and a 2.7 V regulator (VDDIO). VBOARD is the motherboard logic supply whereas VBATT provides power to the daughterboard. VDDIO is the digital I/O voltage supplying the I2C interface and the control pins. Jumper LK1 to Jumper LK3 on the motherboard define whether the internal regulators input voltage is supplied from the USB port or from external supplies connected to J29. The motherboard regulators are powered from the USB-VBUS line when Jumper LK1 to Jumper LK3 are in the USB position. External voltages can be applied to J29 to supply the motherboard and daughterboard, Jumpers LK1 to LK2 must be set to EXT position to use the external supply option.

The daughterboard contains numerous jumpers, LEDs, and test points for easy evaluation and monitoring of the board.

EVALUATION KIT CONTENTS

ADP8860 evaluation board

ADP8860 daughterboard

USB cable

Evaluation software

ADP8860评估系统主要特性:

Input voltage: 2.3 V to 5.5 V

Evaluates backlight, individual sinks, and dual light sensing

Translates USB to I2C interface

Jumpers for measurement of the LEDs and input supply current

On-board reset push-button and interrupt indicator

Connector to interface external target hardware

On-board regulators

Individually selectable on-board LEDs for backlight and keypad light


图4.ADP8860评估系统主板布局图

ADP8860评估板电路图


图5.ADP8860评估系统主板主电路图


图6.ADP8860评估系统主板接口电路图

图7.ADP8860评估系统子板电路图

ADP8860评估系统主板材料清单(BOM):


ADP8860评估系统子板材料清单(BOM):