SBOU268 November 2021 OPA593
The OPA593EVM can be configured as an improved Howland current pump that provides a transconductance amplifier function, sometimes called a V‑to‑I converter. Configuring the V‑to‑I converter with the EVM requires that one resistor, Riso2 (a wide 2512 size), be changed on the EVM PCB from 0 Ω to 49.9 Ω (2 W). If a different output current range is required, this resistor may need to be a different value. Equation 4 shows the Riso2 relationship to the output current.
Additionally, Rhcp1 (a 0805-size, 10-kΩ resistor) must be installed at that location on the PCB. Rhcp1 resides just above C12, and up and to the right of the current-limit set resistor shorting blocks JP12 through JP16.
Connect jumper shunts as listed in Table 3-4 to configure the OPA593 as an improved Howland current pump. The jumper shunt installations are illustrated in Figure 3-4. The jumper shunts are designated in the BOM as a shunt and have an SH-J# part designator. The jumper shunts appear in the schematic as the red jumpers connected across the various JP# jumper blocks.
Jumper Number | Jumper Shunt Connects | Notes |
---|---|---|
JP1 | VIN– J5 to OPA593 –IN pin, through Ri1 (10 kΩ) | |
JP6 | VIN+ J9 to OPA593 noninverting input through R4 (10 kΩ) | |
JP9 | R8 (10 kΩ) from OPA593 noninverting input to GND | |
JP11 | Open | Enabled mode |
JP13 | Sets current limit to 100 mA | |
JP17 | E/D Com pin | E/D Com pin selection GND |
JP18 | RF1 (10 kΩ) inserted in OPA593 feedback path | |
JP21 | Open | IOUT flows through external load |