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[原创] Maxim MAX16813高效高亮(HB)LED四路驱动方案

关键词:电源管理 HB LED驱动器 DC/DC转换器 MAX16813

时间:2017-06-19 10:14:02       作者:Maxim       来源:中电网

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

图1.MAX16813简化功能框图

图2.MAX16813典型应用电路图

图3.MAX16813电感耦合降压-升压配置图

图4.MAX16813 SEPIC LED驱动器

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

图5.评估板MAX16813 EVK电路图
评估板MAX16813 EVK材料清单:



图6.评估板MAX16813 EVK PCB元件顶层布局和走线图

图7.评估板MAX16813 EVK PCB布局图:SGND层2

图8.评估板MAX16813 EVK PCB布局图:左:PGND层3;右:VCC和PGND焊接层
详情请见:
https://datasheets.maximintegrated.com/en/ds/MAX16813.pdf
https://datasheets.maximintegrated.com/en/ds/MAX16813EVKIT.pdf
MAX16813.pdf
MAX16813EVKIT.pdf

 

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