The XTR115U2K5 is a sensor interface 4-20mA current-loop transmitter Manufactured by Texas Instruments. It uses a single external bipolar transistor to provide a linear current output that is proportional to an input signal. This input signal can be directly coupled to, or isolated from, the output signal. The output can be connected directly between a signal source of <±2V or ±200mV and two external resistances (R1 and R2). The current loop output is programmable over a range from 4 to 20mA for an input range of 0 to full scale, and can be thermal compensated, temperature compensated, and isolated with an external diode, depending on the design. It has low input bias currents, low supply voltage, and fast current settling times, making it suitable for HVAC, process control, and instrumentation applications.