Efficient, high-current, linear LED driver reference design for SpO2 and other medical applications


Design files


This reference design provides a protected, efficient (headroom-controlled), high-current (up to 1.5 A), linear (accurate and fast) light-emitting diode (LED) driver reference design to enable peripheral capillary oxygen saturation (SpO2) and other medical applications. A typical SpO2 application drives current through LEDs. Most of these drivers are integrated with analog front-end devices and work at the typical value of 100 mA. A higher current drive is necessitated to cover wide range of human and veterinary physiology. This design enables self-calibration and uses a look-up table for headroom control to optimally drive LEDs resulting in minimum power dissipation across the control element. The design operated from an input voltage range of 1.8 V to 4.2V and enables LED currents up to 1.5 A.

  • Higher efficiency by providing headroom control to optimally drive LED:
    •  - Built-in self-calibration and look-up table for headroom control
    • Dynamic adjustment of the LED supply voltage, to achieve optimal efficiency at the programmed current levels
  • Diagnostics (LED open, LED short, LED disconnect) and protection mechanism for fault by disconnecting the supply using e-fuse
  • Wide operating input range from 1.8 V to 5.5 V to support all battery type inputs
  • Programmable range selection for LED current (from 100 mA to 1.5 A)
  • Compatible with AFE44xx series EVMs (tested with AFE4403 EVM) for driving LEDs
  • Tested with MSP430G2553 LaunchPad™ and two on-board LEDs (green and red)
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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.

TIDUEK8.PDF (6574 K)

Reference design overview and verified performance test data

TIDRZ89.PDF (347 K)

Detailed schematic diagram for design layout and components

TIDRZ90.PDF (29 K)

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

TIDRZ91.PDF (192 K)

Detailed overview of design layout for component placement

TIDRZ93.ZIP (1622 K)

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


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

TIDRZ92.PDF (946 K)

PCB layer plot file used for generating PCB design layout


Includes TI products in the design and potential alternatives.

Analog switches & muxes

TMUX11193-pA on-state leakage current, 5-V, 2:1 (SPDT), 1-channel precision multiplexer

Data sheet: PDF | HTML
Buck-boost, inverting & split-rail converters (integrated switch)

TPS638022-A, high-efficient, 11-µA quiescent current buck-boost converter in QFN/DFN package

Data sheet: PDF | HTML

TLV7021Low power, small size comparator with open-drain output

Data sheet: PDF | HTML
High-speed op amps (GBW ≥ 50 MHz)

OPA3652.2V, 50MHz, Low-Noise, Single-Supply Rail-to-Rail Operational Amplifier

Data sheet: PDF | HTML
N-channel MOSFETs

CSD13202Q212-V, N channel NexFET™ power MOSFET, single SON 2 mm x 2 mm, 9.3 mOhm

Data sheet: PDF | HTML
N-channel MOSFETs

CSD13306W12-V, N channel NexFET™ power MOSFET, single WLP 1 mm x 1.5 mm, 10.2 mOhm

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

OPA333Micropower, 1.8-V, 17-µA zero-drift CMOS precision operational amplifier

Data sheet: PDF | HTML
eFuses & hot swap controllers

TPS25952.7-V to 18-V, 34mΩ, 0.5-4A eFuse with over voltage protection in small WSON package

Data sheet: PDF | HTML

Start development


Design tools & simulation

Simulation model

TIDA-010043 Simulation — TIDM058.ZIP (25 K)

Technical documentation

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Type Title Date
* Design guide Efficient, high current, linear LED driver reference design for SpO2 Mar. 08, 2019

Related design resources

Hardware development

AFE4403EVM AFE4403 Integrated AFE for Heart-Rate Monitors and Pulse Oximeters Evaluation Module
MSP-EXP430G2ET MSP430™ LaunchPad™ development kit for value line MCU

Reference designs

TIDA-010029 Wearable, 16-phase multi-sensor SpO2 and heart rate monitor (HRM) reference design with Bluetooth® 5

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