9V - 32V input to -28V/1.5A negative output buck-boost LED current regulator


Design files


This reference design uses the TPS40170 sync buck controller in a buck-boost converter to regulate the current in a series string of 6 to 8 LEDs (-28V) at up to 1.5A. Efficiency is greater than 93%. The output current can be adjusted with an external control voltage.

Output voltage options PMP6867.1
Vin (Min) (V) 9
Vin (Max) (V) 32
Vout (Nom) (V) -28
Iout (Max) (A) 1.5
Output Power (W) 42
Isolated/Non-Isolated Non-Isolated
Input Type DC
Topology Buck Boost- Inverting^Buck Boost- Synchronous

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.

SLUU877.PDF (2753 K)

Test results for the reference design, including efficiency graphs, test prerequisites and more

SLUR830.PDF (79 K)

Detailed schematic diagram for design layout and components

SLUR831.PDF (28 K)

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

SLUC337.ZIP (128 K)

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

SLUU878.PDF (154 K)

PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Buck controllers (external switch)

TPS401704.5 V to 60 V Wide-Input Synchronous PWM Buck Controller

Data sheet document-pdfAcrobat PDF open-in-new HTML
General-purpose op amps

TLV271Single, 16-V, 3-MHz operational amplifier

Data sheet document-pdfAcrobat PDF open-in-new HTML

Technical documentation

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Type Title Date
Technical article Power Tips: Don’t be negative on negative supplies! Oct. 01, 2013
Test report PMP6867 Test Results Feb. 15, 2012

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