原标题：TI LP55231 评估参考设计方案

　　TI公司的LP55231是一款应用于照明效果移动设备的9通道LED驱动芯片，内部集成高效电荷泵以驱动高于锂电池供电的LED设备，该芯片内部集成程序存储器，允许在没有微控制器的情况下进行操作。本文首先介绍芯片的简介、特性、内部框图及应用领域，并给出相应设计方案的设计原理图、元器件列表及制板图。

　　The LP55231 is a 9-channel LED driver designed to produce lighting effects for mobile devices. A high-efficiency charge pump enables LED driving over full Li-Ion battery voltage range. The device is equipped with an internal program memory, which allows operation without processor control.

　　The LP55231 maintains excellent efficiency over a wide operating range by autonomously selecting the best charge pump gain based on LED forward voltage requirements. The device is able to automatically enter power-save mode when LED outputs are not active, thus lowering idle current consumption down to 10 μA (typ).

　　LP55231主要特性：

　　• Three Independent Program Execution Engines, 9 Programmable Outputs With 25.5mA Full-scale Current, 8-bit Current Setting Resolution and 12-bit PWM Control Resolution

　　• Adaptive High-efficiency 1x/1.5x Fractional Charge Pump - Efficiency up to 94%

　　• LED Drive Efficiency Up to 93%

　　• Charge Pump With Soft Start and Over-current/Short-circuit Protection

　　• Built-in LED Test

　　• 200 nA Typical Standby Current

　　• Automatic Power Save Mode; IVDD = 10 μA (Typ.)

　　• Two-wire I2C-compatible Control Interface

　　• Flexible Instruction Set

　　• Large SRAM Program Memory

　　• Small Application Circuit

　　• Source (High-side) Drivers

　　• Architecture Supports Color Control

　　LP55231应用：

　　• Fun Lights and Indicator Lights

　　• LED Backlighting

　　• Haptic Feedback

　　• Programmable Current Source

　　图1. LP55231内部方框图

　　LP55231方案介绍：

　　The LP55231 provides flexibility and programmability for dimming and sequencing control. Each LED can be controlled directly and independently through the serial bus (in other words, without programming the engines), or LED drivers can be controlled by programming the execution engines. The LP55231 has three independent program execution engines, so it is possible to form three independently programmable LED banks. LED drivers can be grouped based on their function so that, for example, the first bank of drivers can be assigned to the keypad illumination, the second bank to the “funlights” and the third group to the indicator LED(s). Each bank can contain 1 to 9 LED driver outputs. Instructions for program execution engines are stored in the internal program memory. The total amount of the program memory is 96 instructons and the user can allocate the memory as required by the engines. The LP55231 is programmed using an I2C-compatible serial bus. Of course, it is possible to write programs for the LP55231 in the form of binary data, but the programming tools described in this document offers a more convenient way to write (and read) the registers and the SRAM memory and to program the device.

　　LP55231方案原理图：

　　图2. LP55231方案原理图

　　LP55231方案材料清单：

　　制板图：