A6271: Automotive, High-Current LED Controller

The A6271 is a DC-DC converter controller, providing a programmable constant-current output for driving high-power LEDs in series. The controller is based on a programmable fixed-frequency, peak current-mode control architecture. The DC-DC converter can be configured in a myriad of different switching configurations including boost, buck-boost, and buck (ground-referenced switch).

The A6271 provides a cost-effective solution using an external logic-level MOSFET and minimum additional external components. The maximum LED current is set with a single external sense resistor and can be accurately modulated using a current reference input (analog control). External PWM dimming is possible via the PWMIN input, which also provides a shutdown mode. As an alternative, an internal PWM dimming circuit can be used by programming the PWMIN and DR pins. Either PWM scheme controls the PWMOUT output which drives an external p-channel MOSFET connected in series with the LED string. This MOSFET is also used to isolate the load during certain fault conditions, including output shorts to ground.

The A6271 has been carefully designed to minimize electromagnetic emissions through distributed decoupling and an externally programmable frequency dither circuit configured for the EMI specification CISPR 25. It is also possible to program the fundamental switching frequency below 150 kHz where most EMI standards begin.

The A6271 has a comprehensive set of integrated protection features to protect the IC, the LED driver system, and the LED string against faults. Fixed-output overvoltage protection ensures no maximum voltage rating violations, even under a single point failure of the programmable-output overvoltage protection circuit. Other protection features include: LED overload (boost), output undervoltage (buck or buck-boost), input supply (VIN) undervoltage, 5 V Regulator (VREG) output undervoltage, high-side supply (PWM PMOS) undervoltage, and thermal protection.


  • Automotive high-power LED lighting systems
  • Fog lights, reversing lights, daytime running lights, position lights, headlights

Evaluation Kits

  • APEK6271KLP-01-T: Buck-Boost, x4 LEDs at 400 mA
  • APEK6271KLP-02-T: Boost, x14 LEDs at 150 mA
  • APEK6271KLP-03-T: Boost, x12 LEDs at 500 mA

Astrorep Inc. (Allegro and Sanken Semiconductors, Sanken Power Supplies)
141 John Street, Suite 300
Babylon, NY 11702
Phone: (631)422-2500
Fax: (631)422-2504
Web: www.astrorepinc.com
Email: donna.tweedy@astrorepinc.com

If this is not your local representative, find your local sales rep here.

We'll notify you when there are updates to this product. Sign Up
  • Features and BenefitsFeatures and Benefits
  • PackagingPackaging
  • Technical DocsTechnical Docs
  • NewsNews
  • Automotive AEC-Q100 qualified
  • Constant-current LED drive
  • 4.5 to 50 V supply
  • 53.3 V maximum LED string voltage
  • Boost, buck-boost, and buck switching converters
  • Programmable switching frequency 70 kHz to 700 kHz
  • PWM-controlled PMOS driver allows accurate LED current control at low duty cycles
  • Dimming via external PWM, internal PWM and/or analog dimming
  • Frequency dither scheme for effective spread spectrum to reduce EMI
  • Comprehensive fault protection and Fault Flag

Design Support Tools

Click the image to view larger
Product Image Functional Block Diagram Typical Application

Part Number Specifications and Availability

Part Number Package Type Temperature RoHS
Part Composition /
RoHS Data
Comments Samples Check
Distributor Stock
APEK6271KES-01-T DEMO BOARD -20°C to 85°C No -- Contact your
local sales rep
Check Stock
APEK6271KLP-01-T DEMO BOARD -20°C to 85°C No -- Contact your
local sales rep
Check Stock
APEK6271KLP-02-T DEMO BOARD -20°C to 85°C No -- Contact your
local sales rep
Check Stock
APEK6271KLP-03-T DEMO BOARD -20°C to 85°C No -- Contact your
local sales rep
Check Stock
A6271KLPTR-T 16-lead TSSOP -40°C to 125°C Yes View Data Contact your
local sales rep
Check Stock

Allegro’s products are not to be used in any devices or systems, including but not limited to life support devices or systems, in which a failure of Allegro’s product can reasonably be expected to cause bodily harm.

Copyright © 2017 Allegro MicroSystems, LLC

Sitemap  |  Privacy Policy  |  Contact Webmaster

Follow us on: LinkedIn YouTube Google+ Follow Allegro on Twitter

Careers   |   Contact Sales   |   Home   |   Legal   |   Quality & Environment   |   Request Samples