The AD420 is a complete digital to current loop output converter, designed to meet the needs of the industrial control market. It provides a high precision, fully integrated, low cost single-chip solution for generating current loop signals in a compact 24-lead SOIC or PDIP package. The output current range can be programmed to 4 mA to 20 mA, 0 mA to 20 mA or to an overrange function of 0 mA to 24 mA. The AD420 can alternatively provide a voltage output from a separate pin that can be configured to provide 0 V to 5 V, 0 V to 10 V, ±5 V, or ±10 V with the addition of a single external buffer amplifier. The 3.3 M Baud serial input logic design minimizes the cost of galvanic isolation and allows for simple connection to commonly used microprocessors. It can be used in 3-wire or asynchronous mode and a serial-out pin is provided to allow daisy chaining of multiple DACs on the current loop side of the isolation barrier. The AD420 uses sigma-delta DAC technology to achieve 16-bit monotonicity at very low cost. Full-scale settling to 0.1% occurs within 3 ms. The only external components that are required (in addition to normal transient protection circuitry) are two low cost capacitors which are used in the DAC out- put filter.
4 mA–20 mA, 0 mA–20 mA or 0 mA–24 mA current output
16-bit resolution and monotonicity
±0.012% max integral nonlinearity
±0.05% max offset (trimmable)
±0.15% max total output error (trimmable)
Flexible serial digital interface (3.3 MBPS)
On-Chip loop fault detection
On-chip 5 V reference (25 ppm/°C max)
Asynchronous CLEAR function
Maximum power supply range of 32 V
Output loop compliance of 0 V to VCC - 2.75 V
24-Lead SOIC and PDIP packages
Converter Type - Digital to Analog Converter
Spec Sheet available - Yes
Resolution:
16 bits
Integral Nonlinearity:
±0.012 % (Max)
Offset:
±0.05 % (Max)
Total Output Error:
±0.15 %
Operating Current:
4 to 20 mA
Output Impedance:
25 Mohm
Operating Voltage Range:
12 to 32 V
Operating Temperature (Maximum):
185 F
Operating Temperature (Minimum):
-40 F
AD421
- Loop-powered Digital to 4 to 20 mA Converter