The AD693 is a monolithic signal conditioning circuit which accepts low-level inputs from a variety of transducers to control a standard 4-20 mA, two-wire current loop. An on-chip voltage reference and auxiliary amplifier are provided for transducer excitation; up to 3.5 mA of excitation current is available when the device is operated in the loop-powered mode. Alternatively, the device may be locally powered for three-wire applications when 0-20 mA operation is desired.
Precalibrated 30 mV and 60 mV input spans may be set by simple pin strapping. Other spans from 1 mV to 100 mV may be realized with the addition of external resistors. The auxiliary amplifier may be used in combination with on-chip voltages to provide six precalibrated ranges for 100 (ohm) RTDs. Output span and zero are also determined by pin strapping to obtain the standard ranges: 4-20mA, 12 ± 8 mA and 0-20 mA.
Active laser trimming of the AD693's thin-film resistors result in high levels of accuracy without the need for additional adjustments and calibration. Total unadjusted error is tested on every device to be less than 0.5% of full scale at +25°C, and less than 0.75% over the industrial temperature range. Residual nonlinearity is under 0.05%. The AD693 also allows for the use of an external pass transistor to further reduce errors caused by self-heating.
For transmission of low-level signals from RTDs, bridges and pressure transducers, the AD693 offers a cost-effective signal conditioning solution. It is recommended as a replacement for discrete designs in a variety of applications in process control, factory automation and system monitoring.
The AD693 is packaged in a 20-pin ceramic side-brazed DIP, 20-pin Cerdip, and 20-pin LCCC and is specified over the -40°C to +85°C industrial temperature range.
Features and Benefits4-12 mA Unipolar 0-20 mA Unipolar 12 ± 8mA Bipolar | Interface & IsolationAmplifiers |
| Document | note |
| AD693: Loop-Powered 4-20 mA Sensor Transmitter Data Sheet (Rev. A) | PDF 496 kB |
| Document | note |
| AN-275: Versatile Transmitter Chip Links Strain Gauges and RTDs to Current Loop | PDF 948 kB |
| Document | note |
| Part Number | Package | Packing Qty | Temp Range | Price 100-499 | Price 1000+ | RoHS |
|---|---|---|---|---|---|---|
| AD693AD Production | 20 ld Side-Brazed CerDip | OTH 19 | -40 to 85C | 25.7 | 23.19 | N |
| AD693AE Production | 20 ld LCC | OTH 54 | -40 to 85C | 26.87 | 24.25 | Y |
| AD693AQ Production | 20 ld CerDIP | OTH 18 | -40 to 85C | 10.7 | 9.28 | N |
