AD421BRZRL Digital Integrated Circuit 16bit Loop Powered 4 Ma To 20 Ma Dac Converter,Loop-Powered 4 mA to 20 mA DAC​

Applications

• Industrial automation

• Motor control

• Power supplies

• Solar inverters

• Medical equipment

Specifications

Description

The AD421 is a complete, loop-powered, digital to 4 mA to 20 mA converter, designed to meet the needs of smart transmitter manufacturers in the Industrial Control industry. It provides a high precision, fully integrated, low cost solution in a compact 16-lead package.

The AD421 is ideal for extending the resolution of smart 4 mA to 20 mA transmitters at very low cost. The AD421 includes a selectable regulator that is used to power itself and other devices in the transmitter. This regulator provides either a +5 V, +3.3 V or +3 V regulated output voltage. The part also contains +1.25 V and +2.5 V precision references.

The AD421 thus eliminates the need for a discrete regulator and voltage reference. The only external components required are a number of passive components and a pass transistor to span large loop voltages.

The AD421 can be used with standard HART FSK protocol communication circuitry without any degradation in specified performance. The high speed serial interface is capable of operating at 10 Mbps and allows for simple connection to commonly-used microprocessors and microcontrollers via a standard three-wire serial interface.

Features

1. The AD421 is a single chip, high performance, low cost solution for generating 4 mA to 20 mA signals for smart industrial control transmitters.

2. The AD421’s regulated supply voltage can be used to power any additional circuits in the transmitter. The regulated output value is pin selectable as either +3 V, +3.3 V or +5 V.

3. The AD421’s on-chip references can provide a precision reference voltage to other devices in the system. This reference voltage can be either +1.25 V or +2.5 V.

4. The AD421 is fully compatible with standard HART circuitry or other similar FSK protocols.

5. With the addition of a single discrete transistor, the AD421 can be operated from VCC + 2 V min to a maximum of the breakdown voltage of the pass transistor.

6. The AD421 converts the digital data to current with 16-bit resolution and monotonicity. Full-scale settling time to ±0.1% typically occurs within 8 ms.

7. The AD421 features a programmable alarm current capability that allows the transmitter to send out of range currents to indicate a transducer fault

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