0 to 5V Input, 0 mA to 500mA Output, Converter Design


This Verified Design provides the theory, component selection, simulation, PCB design, and measurement details for a low-side voltage-to-current (V-I) converter. The circuit delivers a well-regulated current to a floating load which could include actuators, sensors, motors, LEDs, and many other applications. The design uses the OPA735 small-signal op amp to control an NPN emitter-follower that sources current to the load. The current is accurately regulated by feeding back the voltage drop across a low-side current-sense resistor to the op amp. The rail-to-rail input/output topology of the OPA735 allows for good accuracy even at low currents because there is very little "dead-zone" in either the input or output stage. The auto-zero zero-drift technology in the OPA735 allows for great DC performance over temperature.

  • Converts Voltage to current: 0 to 5 V, 0 mA to 500 mA
  • 1 % Error
  • Single-supply solution with rail-to-rail input op amp
  • Good compliance voltage to the both rails
  • Design allows for a floating load
  • Excellent DC performance and temperature drift using zero-drift OPA735 op amp


Source: http://www.ti.com/tool/TIPD101#1