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Maxim公司的MAX16838是集成了DC/DC開關升壓轉換器和兩個150mA電流沉的雙路LED驅動器,輸入電壓4.75V到40V,升壓或SEPIC電源配置,200Hz的PWM調光比為5000:1,具有漏極開路故障指示輸出以及LED開路/短路檢測和保護,輸出過壓和超溫保護,主要用在汽車顯示器背光,汽車照明和LCD顯示器背光.本文介紹了MAX16838主要特性, 方框圖和升壓-降壓配置框圖, SEPIC配置框圖, 典型應用電路圖以及MAX16838評估板主要特性,電路圖,材料清單和PCB布局圖. The MAX16838 is a dual-channel LED driver that integrates both the DC-DC switching boost regulator and two 150mA current sinks. A current-mode switching DC-DC controller provides the necessary voltage to both strings of HB LEDs. The MAX16838 accepts a wide 4.75V to 40V input voltage range and directly withstands automotive load-dump events. For a 5V ±10% input voltage, connect VIN to VCC. The wide input range allows powering HB LEDs for small-to-medium-sized LCD displays in automotive and display backlight applications. An internal current-mode switching DC-DC controller supports the boost or SEPIC topologies and operates in an adjustable frequency range between 200kHz and 2MHz. The current-mode control provides fast response and simplifies loop compensation. The MAX16838 also features an adaptive output-voltage adjustment scheme that minimizes the power dissipation in the LED current sink paths. The MAX16838 can be combined with the MAX15054 to achieve a buck-boost LED driver with two integrated current sinks. The channel current is adjustable from 20mA to 150mA using an external resistor. The external resistor sets both channel currents to the same value. The device allows connecting both strings in parallel to achieve a maximum current of 300mA in a single channel. The MAX16838 also features pulsed dimming control with minimum pulse widths as low as 1µs, on both channels through a logic input (DIM). The MAX16838 includes an output overvoltage protection, open LED, shorted LED detection, and overtemperature protection. The device operates over the -40°C to +125°C automotive temperature range. The MAX16838 is available in the 20-pin TSSOP and 4mm x 4mm, 20-pin TQFN packages. MAX16838主要特性: Integrated, 2-Channel, 20mA to 150mA Linear LED Current Sinks Boost or SEPIC Power Topologies for Maximum Flexibility Adaptive Voltage Optimization to Minimize Power Dissipation in Linear Current Sinks 4.75V to 40V or 5V ±10% Input Operating Voltage Range 5000:1 PWM Dimming at 200Hz Open-Drain Fault Indicator Output LED Open/Short Detection and Protection Output Overvoltage and Overtemperature Protection Programmable LED Current Foldback at Lower Input Voltages 200kHz to 2MHz Resistor Programmable Switching Frequency with External Synchronization Current-Mode Control Switching Stage with Internal Slope Compensation Enable Input Thermally Enhanced, 20-Pin TQFN (4mm x 4mm) and 20-Pin TSSOP Packages MAX16838應用: Automotive Display Backlights Automotive Lighting Applications LCD Display Backlights 
圖1. MAX16838方框圖
圖2. MAX16838 SEPIC配置框圖
圖3. MAX16838升壓-降壓配置框圖
圖4. MAX16838典型應用電路圖 The MAX16838 evaluation kit (EV kit) demonstrates the MAX16838 high-brightness LED (HB LED) driver, integrating a step-up DC-DC preregulator followed by two channels of linear current sinks. The step-up preregulator switches at 500kHz and operates as a current-modecontrolled regulator capable of providing up to 300mA for the linear circuits. Each channel is capable of operating up to 33V and provides up to 150mA. The channels are configurable for 100mA or 150mA HB LED output current. The MAX16838 IC is available in a 20-pin TQFN package with an exposed pad for enhanced thermal power dissipation. The MAX16838 EV kit operates from a DC supply voltage of 7V up to the HB LED string-forward voltage. The EV kit can withstand a 40V load-dump condition. The EV kit also demonstrates the MAX16838 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. MAX16838評估板主要特性: Input Voltage from 7V Up to HB LED Forward Voltage Demonstrates Overvoltage Protection (35.6V) HB LED String Output Currents Configurable for 100mA or 150mA Demonstrates UVLO (6.4V) Demonstrates Cycle-by-Cycle Current Limit and Thermal Shutdown Features Demonstrates Adaptive Output-Voltage Optimization Configurable LED Current Foldback (VIN < 6.5V) Proven PCB and Thermal Design Fully Assembled and Tested
圖5.MAX16838評估板電路圖 MAX16838評估板材料清單(BOM):
圖6.MAX16838評估板元件布局圖 詳情請見: http://datasheets.maxim-ic.com/en/ds/MAX16838.pdf 和 http://datasheets.maxim-ic.com/en/ds/MAX16838EVKIT.pdf |
