Maxim MAX16814四路高亮LED驱动方案
The MAX16814 high-efficiency, high-brightness LED (HB LED) driver provides up to four integrated LED current-sink channELs. An integrated current-mode switching DC-DC controller drives a DC-DC converter that pro-vides the necessary voltage to multiple strings of HB LEDs. The MAX16814 accepts a wide 4.75V to 40V input voltage range and withstands direct automotive load-dump events. The wide input range allows powering HB LEDs for small to medium-sized LCD displays in automotive and general lighting applications.
An internal current-mode switching DC-DC controller supports the boost, coupled-inductor boost-buck, or SEPIC topologies and operates in an adjustable fre-quency range between 200kHz and 2MHz. It can also be used for single-inductor boost-buck topology in conjunc-tion with the MAX15054 and an additional MOSFET. The current-mode control with programmable slope com-pensation provides fast response and simplifies loop compensation. The MAX16814 also features an adaptive output-voltage control scheme that minimizes the power dissipation in the LED current-sink paths.
The MAX16814 consists of four identical linear current source channels to drive four strings of HB LEDs. The channel current is adjustable from 20mA to 150mA with an accuracy of ±3% using an external resistor. The external resistor sets all 4-channel currents to the same value. The device allows connecting multiple channels in parallel to achieve higher current per LED string. The MAX16814 also features pulsed dimming control, on all four channels through a logic input (DIM). In addition,the MAX16814A_ _ and MAX16814U_ _ include a unique feature that allows a very short minimum pulse width as low as 1μs.
The MAX16814 includes an output overvoltage, open- LED detection and protection, programmable shorted LED detection and protection, and overtemperature pro-tection. The device operates over the -40NC to +125NC automotive temperature range. The MAX16814 is avail-able in 6.5mm x 4.4mm, 20-pin TSSOP and 4mm x 4mm, 20-pin TQFN packages.
MAX16814主要特性:
4-Channel Linear LED Current Sinks with Internal MOSFETs Full-Scale LED Current Adjustable from 20mA to 150mA Drives One to Four LED Strings Boost, SEPIC, or Coupled-Inductor Boost-Buck Current-Mode DC-DC Controller 200kHz to 2MHz Programmable Switching Frequency External Switching Frequency Synchronization
Adaptive Output-Voltage Optimization to Minimize Power Dissipation
4.75V to 40V Operating Input Voltage Range
Less than 40μA Shutdown Current
5000:1 PWM Dimming at 200Hz (MAX16814A _ _ and MAX16814U_ _ Only)
Open-Drain Fault Indicator Output
Open-LED and LED Short Detection and Protection
Overtemperature Protection
Thermally Enhanced, 20-Pin TQFN and TSSOP Packages
MAX16814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.MAX16814 简化功能框图
图2.MAX16814典型应用电路图
图3.MAX16814 SEPIC配置图
图4.MAX16814电感耦合升压-降压配置图
MAX16814 评估板
The MAX16814 evaluation kit (EV kit) demonstrates the MAX16814 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-modecontrolled regulator capable of providing up to 600mA for the linear circuits. Each of the 4 linear channels can operate up to 40V and provide up to 150mA per channel. The 4 channels are configurable for 100mA or 150mA HB LED output current. The IC is a 20-pin TSSOP package with an exposed pad for enhanced thermal power dissipation.
The EV kit operates from a DC supply voltage of 6.5V up to the HB LED string forward voltage. The EV kit can withstand a 40V load-dump condition. The EV kit also demonstrates the IC 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 also demonstrates a reference IC design for automotive applications.
MAX16814 评估板主要特性:
Input Voltage from 6.5V Up to HB LED Forward Voltage
Demonstrates OVP (33V)
HB LED String Output Currents Configurable for 100mA or 150mA
Demonstrates UVLO (5V)
Demonstrates Open and Short LED Fault Protection and Detection
Demonstrates Cycle-by-Cycle Current Limit and Thermal-Shutdown Features
Demonstrates Adaptive Voltage Optimization
Proven PCB and Thermal Design
Fully Assembled and Tested
图5.MAX16814 评估板电路图MAX16814 评估板材料清单:
图6.MAX16814 评估板元件布局图
图7.MAX16814 评估板PCB布局图
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