NXP公司的UBA3077HN是高效LED驱动器，工作电压从10V到42V，5V可用于低压电路，能驱动每串20个的3串LED，每串电流高达150mA，电流精度±2 %，三个升压转换器的输出可高达75V，恒定500kHz频率峰值电流模式控制，主要用于通用LED照明和背景光LCD显示器.本文介绍了UBA3077HN主要特性， 方框图以及典型应用框图和相应元件值.

 The UBA3077HN is a high efficiency LED driver in an HVQFN40 package for general LED lighting or backlighting LCD displays.

 Operating from a supply of 10 V to 42 V， it can drive up to 3 strings of 20 LEDs each. The low voltage circuitry is powered by an external 5 V voltage supply.

 The chip can operate autonomously or be controlled via a 400 kHz I2C-bus. The peak current in each string is fixed by an external resistor. Three independent Pulse-Width Modulated (PWM) signals are available for dimming purposes. These PWM signals are delivered either directly by the graphic processor (direct control mode) to the pins PWM1， PWM2 and PWM3， or generated on-board based on data sent via the I2C-bus interface. Each LED string is supplied by its own boost converter delivering an output voltage from VIN up to 75 V. The switching frequency is 500 kHz.

 A power saving mode is entered when all PWM signals stay LOW for a period longer than 1 s. Several protection mechanisms are available: overvoltage， short-circuit and open LED， overcurrent， UnderVoltage LockOut (UVLO) and overtemperature with an advanced adaptive protection. An error self-recovery (hiccup) mechanism is available with programmable delay time via an external capacitor.

 UBA3077HN主要特性:

􀂄 Three-channel LED backlight driver

􀂄 Up to 150 mA per channel

􀂄 ±2 % absolute LED current accuracy and channel-to-channel matching

􀂄 Peak LED current programmable with external resistor

􀂄 External power supply voltage from 10 V to 42 V and 5 V for low voltage circuitry

􀂄 Three boost converters from VIN up to 75 V output voltage

􀂄 Constant 500 kHz frequency peak current mode control

􀂄 High efficiency up to 90 %

􀂄 Low value output capacitor (2 μF) 􀂄 14-bit PWM dimming (either defined by system-generated PWMs， or internally generated) from 2.0 kHz to 24 kHz (duty cycle from 0.1 % to 100 %)

􀂄 Accurate internal oscillator

􀂄 All power FETs integrated

􀂄 Possible control by I2C-bus with 2-bit address plus a common address for simultaneous configuration of several devices

􀂄 Dedicated reference voltage input for host interface signals

􀂄 OverVoltage Protection (OVP)

􀂄 2.5 A coil current limitation

􀂄 Adaptive thermal protection

􀂄 UVLO

􀂄 Power-On-Reset (POR)

􀂄 Short-circuit protection

􀂄 Open LED detection

􀂄 OverCurrent Protection (OCP) if external resistor value is wrong

􀂄 LX slope limited at 4 V/ns

􀂄 Programmable LED current rise time limitation (250 ns or 500 ns)

􀂄 Hiccup delay programmable via an external capacitor

􀂄 Automatic low-power mode switching if PWM LOW period is too long

􀂄 General LED lighting

􀂄 Display LED backlight for TV/computing applications: Content Active Backlight Control
(CABC)

图1.UBA3077HN方框图

图2.UBA3077HN典型应用框图(1)

图3.UBA3077HN典型应用框图(2)