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[原创] TI TPS92692高精度峰值电流模式LED驱动方案

关键词:电源管理 LED驱动器 电流模式LED控制器 TPS92692

时间:2017-05-19 11:05:36       作者:TI        来源:中电网

TI公司的TPS92692和TPS92692-Q1是基于高精度峰值电流模式LED控制器,可配置成降压/升压模式,输入电压4.5V-65V,在–40°C 到 150°C结温下LED电流精度优于± 4%,采用扩频调制以改善EMI,调光范围1000:1,主要用在汽车外部照明,驱动器监视系统(DMS),LED通用照明,安全出口标记和应急照明.本文介绍了TPS92692主要特性,功能框图以及应用电路,评估板TPS92692EVM-880主要特性和连接图,升压配置电指标,电路图,材料清单和PCB装配图与设计图.

The TPS92692 and TPS92692-Q1 are high accuracypeak current mode based controllers designed tosupport step-up/down LED driver topologies. Thedevice incorporates a rail-to-rail current amplifier tomeasure LED current and spread spectrum frequencymodulation technique for improved EMI performance.

This high performance LED controller canindependently modulate LED current using eitheranalog or PWM dimming techniques. Linear analogdimming response with over 15:1 range is obtainedby varying the voltage across the high impedanceanalog adjust (IADJ) input. PWM dimming of LEDcurrent is achieved by directly modulating theDIM/PWM input pin with the desired duty cycle or byenabling the internal PWM generator circuit. ThePWM generator translates the DC voltage atDIM/PWM pin to corresponding duty cycle bycomparing it to the internal triangle wave generator.The optional PDRV gate driver output can be used todrive an external P-Channel series MOSFET.

The TPS92692 and TPS92692-Q1 devices supportcontinuous LED status check through the currentmonitor (IMON) output. The devices also include anopen drain fault indicator output to indicate LEDovercurrent, output overvoltage and outputundervoltage conditions.

TPS92692主要特性:

• Wide Input Voltage: 4.5 V to 65 V
• Better than ± 4% LED Current Accuracy over–40℃ to 150℃ Junction Temperature Range
• Spread Spectrum Frequency Modulation forImproved EMI
• Comprehensive Fault Protection Circuitry withCurrent Monitor output and Open Drain Fault FlagIndicator
• Internal Analog Voltage to PWM Duty CycleGenerator for stand-alone Dimming Operation
• Compatible with Direct PWM Input with over1000:1 Dimming Range
• Analog LED Current Adjust Input (IADJ) with over15:1 Contrast Ratio
• Integrated P-Channel Driver to enable Series FETDimming and LED Protection
• TPS92692-Q1: Automotive Q100 Grade 1Qualified

TPS92692应用:

• TPS92692-Q1: Automotive Exterior LightingApplications
• Driver Monitoring Systems (DMS)
• LED General Lighting Applications
• Exit Signs and Emergency Lighting

图1.TPS92692功能框图

图2.TPS92692升压LED驱动器应用电路图

图3.TPS92692降压-升压LED驱动器电路图

图4.TPS92692 SEPIC LED驱动器电路图

图5.TPS92692带高边电流检测的升压LED驱动器电路图

评估板TPS92692EVM-880

The TPS92692EVM-880 evaluation module (EVM) helps designers evaluate the operation andperformance of the TPS92692-Q1 and TPS92692: high-accuracy LED controllers designed for automotivelighting and general illumination applications. The TPS92692EVM-880 uses the TPS92692-Q1 ( AECQ100) device; however, for general illumination and other non-automotive applications, the TPS92692 isavailable in the same package and pin configuration and with identical performance characteristics.The TPS92692-Q1 device implements a fixed-frequency peak current mode control technique withprogrammable switching frequency, slope compensation, and startup timing. It incorporates a low offsetrail-to-rail current sense amplifier that can directly measure LED current over an output voltage range of 0V to 65 V. Additional features include wide input voltage range (4.5 V to 65 V), spread spectrum frequencymodulation, analog-to-PWM translation circuit, direct PWM dimming capability, analog dimming capability,adjustable switching frequency, input undervoltage protection, output overvoltage protection, and switchcycle-by-cycle current limit. The controller can be used to implement a range of LED driver topologiesincluding Boost, Buck-Boost (Boost-to-Battery), SEPIC, and Flyback, based on the output LED stackvoltage.

The TPS92692EVM-880 is a fully assembled and tested LED driver that can be configured as either aBoost or a Boost-to-Battery topology to power a single string of series-connected LEDs. High accuracy,closed-loop LED current regulation is achieved using a low-offset rail-to-rail current sense amplifier alongwith high-side current-sensing implementation. The DC LED current set point can be varied over a 15:1ratio using the high-impedance analog adjust (IADJ) input. PWM dimming of LED current is achieved by
directly modulating the DIM/PWM input pin with the desired duty cycle or by enabling the internal PWMgenerator circuit. The optional PDRV gate driver output can be used to drive an external P-Channel seriesMOSFET.

The TPS92692 and TPS92692-Q1 support continuous LED status checks through the current monitor(IMON) output. The device also includes an open-drain fault indicator output that indicates LEDovercurrent, output overvoltage, and output undervoltage conditions.

评估板TPS92692EVM-880主要特性:

• Versatile LED driver capable of driving a string of 1 to 20 series-connected white LEDs
• Wide input voltage range of 4.5 V to 18 V
• Better than ±4% LED current regulation using a high-side current sense resistor
• Spread spectrum frequency modulation for improved EMI
• Internal analog voltage to PWM duty cycle generator for stand-alone dimming operation
• Supports Boost, Buck-Boost (Boost-to-Battery), SEPIC, and Flyback LED driver topologies

图6.评估板TPS92692EVM-880连接图
评估板TPS92692EVM-880升压配置电指标:


图7.评估板TPS92692EVM-880电路图:配置成升压LED驱动器

图8.评估板TPS92692EVM-880电路图:配置成降压-升压LED驱动器
评估板TPS92692EVM-880材料清单:



图9.评估板TPS92692EVM-880装配图

图10.评估板TPS92692EVM-880 PCB顶层布局和覆盖层

图11.评估板TPS92692EVM-880 PCB底层布局和覆盖层
详情请见:
http://www.ti.com/lit/ds/symlink/tps92692.pdf
http://www.ti.com/lit/ug/slvub29/slvub29.pdf
slvub29.pdf
tps92692.pdf

 

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