原标题：Maxim MAX16813高效高亮(HB)LED四路驱动方案

　　Maxim公司的MAX16813是四路高效高亮LED(HB LED)驱动器,其集成的电流模式开关控制器驱动DC/DC转换器,可驱动多串HB LED.输入电压4.75V-40V, LED电流在20mA到150mA内可调整,200Hz时的PWM调光10000:1,可编程开关频率200kHz到2MHz,主要用在汽车显示LED背光源,汽车RCL,DRL,前位和雾灯,LCD TV和台式显示器LED背光源,建筑,工业和环境照明.本文介绍了MAX16813优势和主要特性,框图和多种应用电路以及MAX16813优势和主要特性,电路图,材料清单和PCB设计图.

　　The MAX16813 high-efficiency, high-brightness LED (HBLED) driver provides four integrated LED current-sinkchannels. An integrated current-mode switching controller drives a DC-DC converter that provides the necessaryvoltage to multiple strings of HB LEDs. The deviceaccepts a wide 4.75V to 40V input voltage range andwithstands direct automotive load-dump events. Thewide input range allows powering HB LEDs for small- tomedium-sized LCD displays in automotive and generallighting applications.

　　An internal current-mode switching DC-DC controllersupports boost or SEPIC topologies and operates in anadjustable frequency range between 200kHz and 2MHz.An integrated spread-spectrum mode helps reduce EMI.Current-mode control with programmable slope compensationprovides fast response and simplifies loop compensation.An adaptive output-voltage control scheme minimizespower dissipation in the LED current-sink paths.

　　The device has a separate p-channel drive (PGATE) pinthat is used for output undervoltage protection. Wheneverthe output falls below the threshold, the external p-MOSFET is latched off, disconnecting the input source.

　　Cycling the EN or the input supply is required to restartthe converter. The external p-MOSFET is off when the ENpin is below 0.3V (typ). The shutdown current is 1μA (typ)at an input voltage of 12V.

　　The device consists of four identical linear current-sinkchannels, adjustable from 20mA to 150mA with anaccuracy of ±3% using a single external resistor. Multiplechannels can be connected in parallel to achieve highercurrent per LED string. The device also features a uniquepulsed dimming control through a logic input (DIM),with minimum pulse width as low as 500ns.

　　Protectionfeatures include output overvoltage, open-LED detectionand protection, programmable shorted LED detection andprotection, output undervoltage protection and detection,and overtemperature protection. The device operatesover the -40℃ to +125℃ automotive temperature range.

　　The MAX16813 is available in 20-pin (6.5mm x 4.4mm)TSSOP and 20-pin (4mm x 4mm) TQFN packages.

　　MAX16813是一款高效率、高亮度LED (HB LED)驱动器，提供四路集成的LED灌电流通道。集成电流模式开关控制器驱动DC-DC转换器，提供用于驱动各串HB LED的电压。器件输入电压范围为4.75V-40V，并可承受汽车抛负载。较宽的输入范围非常适合小尺寸到中等尺寸的LCD，用于汽车显示器及通用照明的HB LED供电。

　　内置电流模式DC-DC开关控制器，支持Boost或SEPIC拓扑，工作频率可在200kHz到2MHz范围调节，集成扩频技术有助于降低EMI。电流模式控制的可编程斜率补偿技术提供快速响应和简单的环路补偿。自适应输出电压控制架构减小了LED灌电流通路的功率损耗。器件拥有一个独立的P沟道驱动引脚(PGATE)，用于输出欠压保护。当输出电压低于阈值时，外部p-MOSFET关断，以断开输入电源。重新触发EN或重启输入电源，重新开启转换器。当EN引脚低于0.3V (典型值)时，外部p-MOSFET关闭。输入电压为12V时，关断电流为1µA (典型值)。

　　此器件由四路完全相同的线性、灌电流通道组成，通过外部电阻调节电流，调节范围：20mA - 150mA，±3%电流精度。多个通道可以并联，以提高每串LED的驱动电流。器件还通过一个逻辑输入(DIM)提供脉冲调光功能，最小脉宽低至500ns。保护功能包括：输出过压保护、LED开路检测和保护、可编程LED短路检测和保护、输出欠压检测和保护，以及高温检测。器件工作在-40°C至+125°C汽车级温度范围。提供20引脚TSSOP封装(6.5mm × 4.4mm)和TQFN封装(4mm × 4mm)。

　　MAX16813: Typical Operating Circuit

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　　关键特性

　　4通道线性LED灌电流驱动，内置MOSFET

　　LED电流调节范围：20mA-150mA

　　可驱动1至4串LED

　　Boost或SEPIC电流模式DC-DC控制器

　　200kHz-2MHz可编程开关频率

　　外部时钟同步

　　扩频模式降低EMI

　　自适应输出电压优化，降低功耗

　　输出欠压保护(以地为参考)

　　4.75V至40V工作电压范围

　　关断电流小于2µA

　　200Hz下，提供10000:1PWM调光

　　开漏输出故障指示

　　LED开路和短路检测及保护

　　过温保护

　　增强散热的20引脚TQFN和TSSOP封装

　　应用

　　建筑、工业及环境照明

　　汽车显示器LED背光

　　汽车RCL、DRL、前车灯和雾灯

　　LCD TV和台式机显示器LED背光

　　MAX16813优势和主要特性:

　　● 4-Channel Linear LED Current Sinks with InternalMOSFETs Independently Drive Multiple LED Strings

　　• Full-Scale LED Current Adjustable from 20mAto 150mA

　　• Drives 1 to 4 LED Strings

　　• 10000:1 PWM Dimming at 200Hz

　　● Flexible Current-Mode Architecture Supports a WideRange of Applications While Minimizing Interference

　　• Boost or SEPIC Current-Mode DC-DC Controller

　　• 200kHz to 2MHz Programmable SwitchingFrequency

　　• External Switching-Frequency Synchronization

　　• Spread-Spectrum Mode

　　● Protection Features Enhance Fault Detection andSystem Reliability

　　• Output-to-Ground Undervoltage Protection

　　• Open-Drain Fault-Indicator Output

　　• Open-LED and LED-Short Detection andProtection

　　• Overtemperature Protection

　　● Adaptive Output-Voltage Optimization to MinimizePower Dissipation

　　• Less than 2μA Shutdown Current

　　MAX16813应用:

　　● Automotive Displays LED Backlights

　　● Automotive RCL, DRL, Front Position, and Fog Lights

　　● LCD TV and Desktop Display LED Backlights

　　● Architectural, Industrial, and Ambient Lighting

　　评估板MAX16813 EVK

　　The MAX16813 evaluation kit (EV kit) demonstrates the MAX16813 high-brightness LED (HB LED) driver, integrating a step-up DC-DC preregulator followed by 4 channels of linear current sinks. The step-up preregulator switches at 350kHz and operates as a current-mode-controlled regulator capable of providing up to 600mA for the linear circuits. Each of the 4 linear channels are capable of operating up to 40V and provide up to 150mA per channel. The 4 channels are configurable for 100mA or 150mA HB LED output current.

　　The EV kit operates from a 6.5V DC supply voltage up to the HB LED string-forward voltage. The EV kit can withstand a 40V load-dump condition for up to 400ms. The EV kit demonstrates the device features such as adaptive voltage optimization, undervoltage lockout (UVLO), overvoltage protection (OVP), cycle-by-cycle current limit, thermal shutdown, and digital PWM dimming operation using a digital PWM input signal to control the brightness of the HB LEDs. The EV kit includes an external pMOSFET (Q2) that can be used to disconnect the boost output from the battery in the event of an output overload or short condition.

　　评估板MAX16813 EVK主要特性:

　　● 6.5V Up to HB LED Forward Voltage

　　● Demonstrates OVP (33V)

　　● HB LED String Output Currents Configurable for 100mA or 150mA

　　● Demonstrates UVLO (4V)

　　● Demonstrates Cycle-by-Cycle Current-Limit and Thermal-Shutdown Features

　　● Demonstrates Adaptive-Voltage Optimization

　　● Demonstrates Output Short Protection and Ultra-Low Current Shutdown

　　● Proven PCB and Thermal Design

　　● Fully Assembled and Tested

MAX16813EVKIT.pdf

MAX16813.pdf