company blog about ADI AD421BRZRL High-Performance Loop-Powered 4mA To 20mA Digital To Analog Converters Solution

ADI AD421BRZRL High-Performance Loop-Powered 4mA To 20mA Digital To Analog Converters Solution

Shenzhen Mingjiada Electronics Co., Ltd., a well-known distributor of electronic components, offers the ADI AD421BRZRL loop-powered 4mA to 20mA digital-to-analogue converter (DAC) in stock. This device is specifically designed for industrial applications and is widely used in process control, industrial automation, and other fields.

【Product Overview and Core Features】

The AD421BRZRL is a complete loop-powered digital-to-4-20 mA converter designed to meet the needs of smart transmitter manufacturers in the industrial control industry. It offers a high-precision, fully integrated, low-cost solution in a compact 16-pin package. The AD421BRZRL significantly enhances the resolution of smart 4-20 mA transmitters at extremely low cost.

The AD421BRZRL includes an optional regulator for powering itself and other transmitter devices. This regulator provides regulated output voltages of +5 V, +3.3 V, or +3 V. The device also incorporates high-precision reference voltages of +1.25 V and +2.5 V. As a result, the AD421BRZRL eliminates the need for discrete regulators and voltage references. The only external components required are a few passive components and a conduction transistor for bridging the large loop voltage.

The AD421BRZRL can be used with standard HART FSK protocol communication circuits without compromising specified performance. Its high-speed serial interface supports a 10 Mbps data rate and can be easily connected to common microprocessors and microcontrollers via a standard three-wire serial interface.

The DAC's sigma-delta architecture ensures 16-bit monotonicity, while the AD421BRZRL's integral nonlinearity is ±0.01%. The device provides a 4 mA zero-point output current with a offset error of ±0.1%, and a 20 mA full-scale output current with a gain error of ±0.2%.

The AD421BRZRL is available in a 16-pin, 0.3-inch-wide plastic dual in-line package (DIP) and a 16-pin, 0.3-inch-wide single in-line package (SOIC). The device operates within the industrial temperature range of -40°C to +85°C.

The device's key technical features include:

16-bit high resolution: Provides precise output current control with a minimum step size of 305 nA (when the shunt resistor is 250 Ω), meeting the most stringent industrial control accuracy requirements

Loop-powered design: Directly obtains operating power from the 4-20 mA current loop, eliminating the need for an additional power supply, simplifying system wiring, and reducing costs

Low-power operation: Typical operating current is only 500μA, maximising the effective loop current available for sensors and other circuits

Flexible serial interface: Compatible with SPI, QSPI, MICROWIRE, and DSP interface standards, facilitating connection to various microcontrollers and digital systems

Integrated voltage reference: On-chip precision reference voltages of +1.25V or +2.5V are provided, with a typical temperature coefficient of 10ppm/°C, reducing the number of external components

Fault protection features: Includes open-circuit detection and power-on reset functions, enhancing system reliability

Industrial-grade temperature range: Operating temperature range of -40°C to +85°C, suitable for harsh industrial environments

【Product Highlights】

1. The AD421BRZRL is a single-chip, high-performance, low-cost solution for generating 4 mA to 20 mA signals, suitable for smart industrial control transmitters.

2. The AD421BRZRL's regulated supply voltage can be used to power other circuits within the transmitter. The regulated output voltage can be selected via pins to be +3 V, +3.3 V, or +5 V.

3. The reference voltage within the AD421BRZRL chip can provide high-precision reference voltage for other devices in the system. This reference voltage can be +1.25 V or +2.5 V.

4. The AD421BRZRL is fully compatible with standard HART circuits or other similar FSK protocols.

5. By adding a single discrete transistor, the AD421BRZRL can operate from VCC + 2 V (minimum) up to the breakdown voltage of the conduction transistor (maximum).

6. The AD421BRZRL converts digital data to current with 16-bit resolution and monotonicity. Full-scale settling time to ±0.1% is typically completed within 8 milliseconds.

7. The AD421BRZRL features a programmable alarm current function, allowing the transmitter to send an out-of-range current to indicate sensor failure.

【Applications】

Process control systems are the primary application area for the AD421BRZRL. In industries such as chemicals, petroleum, and pharmaceuticals, the 4-20mA current loop is the standard method for transmitting analogue signals between sensors and control systems. The AD421BRZRL can be used for:

Temperature transmitters: Converting thermocouple or RTD signals into standard 4-20mA output

Pressure transmitters: Converting piezoresistive or capacitive pressure sensor signals into loop current

Flow meters: Processing output signals from vortex, electromagnetic, or Coriolis flow meters

Level sensors: Transmitting float, hydrostatic, or ultrasonic level measurement results to the control room

Factory automation systems also widely adopt the AD421BRZRL as the core component of analogue output modules. In PLCs (programmable logic controllers) and DCSs (distributed control systems), the AD421BRZRL can be used for:

Analogue output modules: Providing multi-channel 4-20mA outputs to control field devices such as valves and actuators

Motor speed controllers: Converting digital speed commands into analogue current signals to drive variable frequency drives

Position control systems: Processing encoder data and outputting control signals to drive servo systems

Smart sensors and IoT terminals are emerging application areas for the AD421BRZRL. With the development of industrial IoT (IIoT), an increasing number of sensors require digitalisation and networking capabilities while retaining traditional 4-20mA interfaces. The AD421BRZRL demonstrates unique advantages in such applications:

Provides backward-compatible analogue interfaces for smart sensors

Low-power design extends the runtime of battery-powered devices

Compact packaging suits space-constrained embedded designs

Digital interfaces facilitate connection to microcontrollers and wireless modules

Instrumentation and test equipment are also key application areas for the AD421BRZRL. In scenarios requiring precise current sources or programmable loads, the AD421BRZRL offers a cost-effective solution:

Calibration equipment: Used as a precision current source for calibrating other 4-20mA devices

Data acquisition systems: Provides programmable test signals for analogue input modules

Power supply test equipment: Simulates various load conditions to test power supply performance