ZHCSPX8B january 2000 – june 2023 XTR115 , XTR116
PRODUCTION DATA
The XTR115 and XTR116 are identical devices except for the reference voltage output, pin 1. This voltage is available for external circuitry and is not used internally. Further discussions that apply to both devices refer to the XTR11x.
Figure 8-1 shows basic circuit connections with representative simplified input circuitry. The XTR11x is a two-wire current transmitter. The device input signal (pin 2) controls the output current. A portion of this current flows into the V+ power supply, pin 7. The remaining current flows in Q1. External input circuitry connected to the XTR11x can be powered from VREG or VREF. Current drawn from these terminals must be returned to IRET, pin 3. This IRET pin is a local ground for input circuitry driving the XTR11x.
The XTR11x is a current-input device with a gain of 100. A current flowing into pin 2 produces IO = 100 • IIN. The input voltage at the IIN pin is zero (referred to the IRET pin). A voltage input is created with an external input resistor, as shown. Common full-scale input voltages range from 1 V and upward. Full-scale inputs greater than 0.5 V are recommended to minimize the effect of offset voltage and drift of A1.