Bridge-tied load (BTL) V-I converter, 0.5 V to 4.5 V and up to ±2-A reference design


Design files


This verified design circuit is a bidirectional current source that can be used to drive floating loads, specifically thermo-electric coolers (TECs) from a single-ended source. The circuit makes use of an internal output current monitor circuit (IMON), which is a special feature of the OPA569 power amplifier. The V-I transfer function is accomplished by using the IMON current as the feedback for the first amplifier. This enables the user to create an input signal that cancels the IMON current to achieve a well regulated output current. The second amplifier inverts the output of the first amp to achieve the bridge tied load (BTL) operation, doubling the voltage swing and slew rate across the load, allowing for bidirectional operation and good voltage swing on the single-ended power supply. The excellent output swing-to-rail of the OPA569 allows for 4.5 V of usable output voltage at 2 A output current with a 5 V single-ended power supply.

  • Converts Voltage to current: 0.5 - 4.5 V input, +/- 2A output
  • 5 % Error for coarse bi-directional high-current regulation
  • Single-supply bridge-tied-load solution has excellent output swing to rails at +/-2A
  • Design allows for a floating load
  • Unique topology and V-I transfer function using OPA569 special IMON feature

      This Verified Design Includes:

    • Theory
    • Component Selection
    • TINA-TI Simulation
    • Schematics and PCB Layout
    • Verification and Measured Performance
    • Modification Options

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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.

TIDR182.PDF (99 K)

Detailed schematic diagram for design layout and components

SLAC574.ZIP (790 K)

Detailed schematic diagram for design layout and components

TIDR206.PDF (62 K)

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

TIDC142.ZIP (524 K)

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


Includes TI products in the design and potential alternatives.

Power op amps

OPA569Power Op Amp, Output Signal Swings Within 200mV of Rails at 2A Output Current

Data sheet: PDF
Series voltage references

REF50252.5-V, 3-µVpp/V noise, 3-ppm/°C drift precision series voltage reference

Data sheet: PDF | HTML

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Technical documentation

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Type Title Date
* User guide TIPD103 Verified Design Reference Guide Jun. 18, 2013

Related design resources

Design tools & simulation

TINA-TI SPICE-based analog simulation program

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