Automotive Daytime Running Light Dual String LED Driver Reference Design with Current Balancing


Design files


This reference design is a dual string LED driver that implements an operational amplifier based circuit which balances the current in two LED rings. The operational amplifier circuit senses current in a reference string and uses feedback from a mirrored string to bias a MOSFET that regulates the current between the strings. The design uses the TPS92692-Q1 multi-topology LED driver in a boost configuration to drive the LEDs. The TPS92692-Q1 features spread spectrum frequency modulation for EMI performance, analog current adjustment and internal PWM dimming.  This design includes adjustable linear thermal foldback using the LMT87-Q1 analog temperature sensor, as well as current limiting, in the event the mirrored string fails open circuit. The design also features two brightness modes. One mode is a full brightness mode ('DRL') and the other is a PWM dimming mode ('Position') which reduces brightness.

  • Dual string current balancing using a single LED driver
  • CISPR25 Class 5 conducted and radiated emissions tested
  • PWM dimming
  • Operation without a microcontroller

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.

TIDUDR9.PDF (1435 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


PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Analog temperature sensors

LMT87-Q1Automotive ±2.7°C 2.7V to 5.5V analog output temperature sensor with -13.6 mV/°C gain

Data sheet: PDF | HTML
Automotive LED drivers

TPS92692-Q1high-accuracy LED controller with spread spectrum frequency modulation and internal PWM Generator

Data sheet: PDF | HTML

LM2901V-Q1Automotive Catalog Quad Differential Comparator, Enhanced Voltage

Data sheet: PDF | HTML
General-purpose op amps

TLV2316-Q1Automotive-grade, dual, 5.5-V, 10-MHz, RRIO operational amplifier

Data sheet: PDF | HTML

Technical documentation

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Type Title Date
* Design guide Automotive, Daytime Running Light, Dual-String LED Driver Reference Design Jan. 19, 2018
Technical article Designing daytime running lights, part 2: responding to an LED fault Dec. 06, 2018
Technical article Designing daytime running lights, part 1: adding one-fail-all-fail LED fault detection Dec. 04, 2018

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