SBOS522A June 2010 – November 2019 OPA333-Q1
PRODUCTION DATA.
The V-I transfer function of the circuit is based on the relationship between the input voltage, VIN, RSET, and the instrumentation amplifier (INA) gain. During operation, the input voltage divided by the INA gain appears across the set resistor in Equation 1:
The current through RSET must flow through the load, so IOUT is VSET / RSET × IOUT remains a well-regulated current as long as the total voltage across RSET and RLOAD does not violate the output limits of the operational amplifier or the input common-mode limits of the INA. The voltage across the set resistor (VSET) is the input voltage divided by the INA gain (that is, VSET = 1 V / 10 = 0.1 V). The current is determined by VSET and RSET shown in Equation 2:
A detailed error analysis, design procedure, and additional measured results are given in the Low-Level V-to-I Converter reference design.