Precision PWM Dimming LED Driver Reference Design for Automotive Lighting


Design files


This reference design shows how to use pulse width modulation (PWM) to dim an automotive headlight or tail light with precision of better than 2% duty cycle without the necessity of using a microcontroller. This allows the design to be cost competitive. Devices used in this design are the TPS92691-Q1 multi-topology LED driver in boost and boost to battery configuration controlling the LEDs.  TLC555-Q1 LinCMOS timer, together with OPA2377-Q1 operational amplifier, measure and generate an accurate PWM signal by applying a feedback loop and a precision shunt regulator for setting the duty cycle accurately. The design's input stage is EMI/EMC filtered and can be directly supplied by the car's battery.

  • Precision PWM dimming
  • Efficiency-optimized design
  • Operation through cold crank
  • Load-dump tolerant
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A fully assembled board has been developed for testing and performance validation only, and is not available for sale.

Design files & products

Design files

Download ready-to-use system files to speed your design process.

TIDUC97A.PDF (3158 K)

Reference design overview and verified performance test data


Detailed schematic diagram for design layout and components


Complete listing of design components, reference designators, and manufacturers/part numbers


Detailed overview of design layout for component placement


Files used for 3D models or 2D drawings of IC components


Design file that contains information on physical board layer of design PCB

TIDROE1.PDF (1160 K)

PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Automotive LED drivers

TPS92691-Q1Automotive multi-topology LED driver with rail-to-rail current sense amplifier

Data sheet: PDF | HTML
Precision op amps (Vos<1mV)

OPA2377-Q1Automotive-Qualified, Rail-to-Rail In/Out, Low Noise, 5MHz CMOS Operational Amplifier

Data sheet: PDF | HTML
Shunt voltage references

TL431-Q1Automotive adjustable precision shunt regulator (pin layout: KRA)

Data sheet: PDF | HTML

Technical documentation

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Type Title Date
* Design guide Precision PWM Dimming LED Driver Reference Design for Automotive Lighting (Rev. A) Jan. 12, 2017

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