8.2.1 Design Requirements

Consider the following information during XTR305 circuit configuration:

• Recommended bypassing: 100 nF or more for supply bypassing at each supply.
• R_IMON can be in the kΩ range or short-circuited if not used. Do not leave this current output unconnected — it would saturate the internal current source. The current at this I_MON output is I_DRV / 10. Therefore, V_IMON = R_IMON (I_DRV /1 0).
• R₃ is not required but can match R_SET (or R_SET||R_OS) to compensate for the bias current.
• R_IA can be short-circuited if not used. Do not leave this current output unconnected. R_GAIN is selected to 10 kΩ to match the output of 10 V with 20 mA for the equal input signal.
• R_C ensures stability for unknown load conditions and limits the current into the internal protection diodes. C₄ helps protect the device. Overvoltage clamp diodes (standard 1N4002) might be necessary to protect the output.
• R₆, R₇, and C₅ protect the IA.
• R_LOAD and C_LOAD represent the load resistance and load capacitance.
• R_SET defines the transfer gain. It can be split to allow a signal offset and, therefore, allow a 5-V single-supply digital-to-analog converter (DAC) to control a ±10-V or ±20-mA output signal.

The XTR305 can be used with asymmetric supply voltages; however, the minimum negative supply voltage must be equal to or more negative than −3 V (typically −5 V). This supply value ensures proper control of 0 V and 0 mA with wire resistance, ground offsets, and noise added to the output. For positive output signals, the current requirement from this negative voltage source is less than 5 mA.

GND1 through GND4 must be selected to fulfill specified operating ranges. DGND must be in the range of (V−) ≤ DGND ≤ (V+) −7 V.