Features * 4MA to 20mA transmitter selectable input/output range:
0V to +5V, 0V to + 10V input
0mA to 20mA, 5mA to 25mA output other ranges *Maximum non-linearity 0.005%, 14bit *Accuracy +10V reference output *Single supply operation *Wide supply range: 13.5V to 40V
Description Applications *Industrial Process Control *Pressure/Temperature Transmitters *Current Mode Bridge Excitation *Ground Sensor Circuit Current Source Reference for Data Acquisition *Programmable Current Source Test Equipment Power Plant/Energy Systems
The XTR110 is a precision voltage-to-current converter designed for analog signal transmission. It accepts a 0 to 5V or 0 to 10V input and can connect outputs of 4 to 20mA, 0 to 20mA, 5 to 25mA and many other common ranges.
A precision on-chip metal film resistor network provides input scaling and current offset. An internal 10V voltage reference can be used to drive external circuits.
The XTR110 is available in 16-pin plastic dip, ceramic dip and Sol-16 surface mount packages. Commercial and industrial temperature range models are available.

Basic circuit connections.
If the supply voltage +VCC exceeds the gate-to-source breakdown voltage of QEXT, and the output connection (Drain of QEXT) is open, QEXT may fail. If the gate-to-source breakdown voltage is lower than +VCC, QEXT can be connected from gate to source through a 12V Zener diode.
QEXT can use two PNP discrete transistors (Darlington connection), see Figure 2. Note that additional capacitors are required for stability. Integrated Darlington transistors are not recommended because their internal base-emitter resistors cause excessive errors.
Transistor loss
The maximum power dissipation of the qext depends on the supply voltage and full-scale output current. Assuming a low load resistance, the power dissipated by QEXT is:
Pmax = (+VCC) if (2)
Transistor type and heat dissipation must be chosen based on maximum power dissipation to prevent overheating.

Input Voltage Range If the non-inverting input (internal node) of internal op amp A1 is pulled more than 0.5v below common (0v) it can be damaged. If input pins 3, 4 or 5 are driven by an op amp, its output may be negative under abnormal conditions. The voltage at the input of A1 is:
(VREF in) (VIN1) (VIN2)
Type VA1 = ++ (3) 16, 4, 2
This voltage should not exceed -0.5V. If necessary, connect a clamping diode from the negative input to common to clamp the input voltage.
Normal (Ground)
Proper connection of common (ground) should be noted. All common parts should be connected at a point as close as possible to pin 2 of the XTR110. The exception is that iout returns. It can go back to any point where it will not modulate the common of pin 2.
Voltage Reference The reference voltage is precisely regulated at pin 12 (VREF sense). To maintain accuracy, any load including pin

Low Temperature Coefficient Operation Although the temperature of the precision resistors in the XTR110 is within 1ppm/°C, the output current depends on the absolute temperature coefficient (Tc) of any one of the resistors R6, R7, R8 and R9. Since the absolute tc of the output current can have a maximum value of 20ppm/°C, the tc of the output current can have a drift of 20ppm/°C. For low tc operation, a zero tc resistor can replace either the span resistor (r6 or r7) or the source resistor (r9), but not both.
Extended Span For ranges in excess of 40 mA, the internal 50Ω resistor (R9) can be replaced by an external resistor connected between pins 13 and 16.
Its value can be calculated as follows:
REXT=R9 (wrench/wrench)
Since the internal thin film resistors have a 20% absolute value tolerance, measure R9 before determining the final value of REXT. The self-heating of T. rex causes nonlinearity. Therefore, choose a low tc and adequate power rating. See Figure 10 for applications.
typical application
The XTR110 is ideal for a variety of applications requiring high noise immunity current mode signaling. A precision +10V reference voltage can be used to excite bridges and sensors. The selectable range makes it a very useful precision programmable current source. The XTR110's compact design and low price make it versatile with minimal external components and design engineering costs.
Typical application of the XTR110.

00mA current pump.

Isolated 4ma to 20ma channel.

0A to 10A output voltage-current converter.