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 AD420AR-32 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 AD420AR-32 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 AD420AR-32 uses sigma-delta (Σ-Δ) 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 output
filter.
If the AD420AR-32 is used at extreme temperatures and supply
voltages, an external output transistor can be used to minimize
power dissipation on the chip via the BOOST pin. The FAULT
DETECT pin signals when an open circuit occurs in the loop.
The on-chip voltage reference can be used to supply a precision
+5 V to external components in addition to the AD420AR-32 or, if the
user desires temperature stability exceeding 25 ppm/°C, an
external precision reference such as the AD586 can be used as
the reference. The AD420AR-32 is available in a 24-lead SOIC and
PDIP over the industrial temperature range of −40°C to +85°C.
Feature
- 4mA-20 mA, 0 mA-20 or 0 mA-24Current Output
- 16-Bit Resoluton 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
(Picture: Pinout)
