Features: 420 mA, 020 mA Output Ranges
Precalibrated Input Ranges:
0 V to 2 V, 0 V to 10 V
Precision Voltage Reference
Programmable to 2.000 V or 10.000 V
Single or Dual Supply Operation
Wide Power Supply Range: +4.5 V to +36 V
Wide Output Compliance
Input Buffer Amplifier
Open-Loop Alarm
Optional External Pass Transistor to Reduce
Self-Heating Errors
0.002% typ Nonlinearity
Specifications
INPUT CHARACTERISTICS
Input Voltage Range
Input Bias Current
Either Input, TMIN to TMAX
Offset Current, TMIN to TMAX
Offset Current Drift
Input Impedance |
0.2 Vs2.0 V Vs2.5 V
1.5 5
±0.1 1
±1.0 ±5.0
5 |
0.2 VS2.0 V VS2.5 V
1.5 5
±0.1 ±1
±1.0 ±5.0
5 |
V
nA
nA
pA/°C
M? |
OUTPUT CHARACTERISTICS
Operating Current Range
Specified Performance
Output Voltage Compliance
Output Impedance, 420 mA
Current Limit (@ 2 * FS Overdrive
Slew Rate |
0 23
4 20
Vs6V Vs-2V
0 50.0
24 44
1.3 |
0 23
4 20
VS36 V VS2
40.0 50.0
24 44
1.3 |
mA
mA
V
M?
mA
mA/s |
DescriptionThe AD694 is a monolithic current transmitter that accepts high level signal inputs to drive a standard 420 mA current oop for the control of valves, actuators, and other devices com-monly used in process control. The input signal is buffered by an input amplifier that can be used to scale the input signal or buffer the output from a current mode DAC. Precalibrated in-put spans of 0 V to 2 V and 0 V to 10 V are selected by simple pin strapping; other spans may be programmed with external esistor.
The output stage compliance extends to within 2 V of VS and its special design allows the output voltage to extend below com-mon in dual supply operation. An alarm warns of an open 4-to-20 mA loop or noncompliance of the output stage.Active laser trimming of the AD694's thin film resistors results n high levels of accuracy without the need for additional adjust-ments and calibration. An external pass transistor may be used with the AD694 to off-load power dissipation, extending the emperature range of operation.
The AD694 is the ideal building block for systems requiring noise immune 420 mA signal transmission to operate valves,actuators, and other control devices, as well as for the transmis-sion of process parameters such as pressure, temperature, or low. It is recommended as a replacement for discrete designs in a variety of applications in industrial process control, factory automation, and system monitoring.
The AD694 is available in hermetically sealed, 16-pin cerdip and plastic SOIC, specified over the 40°C to +85°C industrial emperature range, and in a 16-pin plastic DIP, specified over he 0°C to +70°C temperature range.
AD694 Data Sheet
