AD420

Data Sheet FEATURES 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 GENERAL DESCRIPTION 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 (Σ-Δ) DAC technology to achieve 16-bit monotonicity at ver...