Bridge Tied Load (BTL) V-I Converter, 0.5-4.5V to +/-2A
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Key Document


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.

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  • 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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Design Files

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TI Devices (2)

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Part Number Name Product Family Sample & Buy Design Kits & Evaluation Modules
OPA569  Power Op Amp, Output Signal Swings Within 200mV of Rails at 2A Output Current  Operational amplifiers (op amps)  Sample & Buy View Design Kits & Evaluation Modules
REF5025  2.5-V, 3-µVpp/V noise, 3-ppm/°C drift precision series voltage reference  Voltage references  Sample & Buy View Design Kits & Evaluation Modules

CAD/CAE symbols

Part # Package | Pins CAD File (.bxl) STEP Model (.stp)
OPA569 Download Download
REF5025 Download Download
Download Download

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Technical documentation

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User guide (1)
Title Type Size (KB) Date
PDF 971 18 Jun 2013
Design files (4)
Title Type Size (KB) Date
PDF 62 20 Sep 2013
ZIP 524 19 Sep 2013
PDF 99 19 Sep 2013
ZIP 790 12 Jun 2013
Related Tools & Software

Design tools & simulation (1)

Name Part Number Tool Type
SPICE-based analog simulation program  TINA-TI  Simulation tool 

Software development (1)

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