ADR421AR

Overview

The ADR421AR is a series precision voltage reference from Analog Devices, utilizing second-generation XFET technology for high accuracy and low noise. It provides a fixed 2.5 V output with an initial accuracy of ±0.04% (B Grade) or ±0.12% (A Grade). The device operates within a supply voltage range of 4.5 V to 18 V and delivers up to 10 mA of load current. Key electrical specifications include a maximum temperature coefficient of 3 ppm/°C, 1.75 µV p-p noise in the 0.1 Hz to 10 Hz band, and operation across an extended industrial temperature range of −40°C to +125°C.

Feature Summary

• XFET architecture minimizes nonlinearity and offers superior thermal hysteresis compared to standard band gap references.
• Features a dedicated TRIM terminal allowing output voltage adjustment over a ±0.5% range without compromising temperature stability.
• Delivers high output current capability of 10 mA while maintaining low quiescent current consumption.

Applications

• Precision data acquisition systems
• High resolution analog-to-digital converters
• Optical network control circuits

Procurement Notes

Verify the specific grade (A or B) required for your application, as accuracy and temperature coefficients differ between them. Confirm the package type matches your PCB footprint, as this part number typically denotes the SOIC-8 variant. Ensure input voltage headroom meets the minimum 2 V requirement relative to the 2.5 V output. Check for RoHS compliance status if environmental regulations apply to your manufacturing process.

Selection Notes

Select the ADR421AR when system requirements demand ultralow noise performance below 2 µV p-p in the sub-Hz frequency range. Choose this component over band gap references if long-term stability and minimal thermal hysteresis are critical design constraints. Consider the available trim functionality if precise calibration of the reference voltage is necessary during system assembly or testing phases.

Part Context

The ADR421AR belongs to the ADR42x family of ultraprecision voltage references, which also includes the ADR420, ADR423, and ADR425 models. These devices share the same core XFET technology and pinout but offer different nominal output voltages ranging from 2.048 V to 5.00 V. The family is designed to replace older buried Zener references while offering lower power consumption and smaller package footprints.

Replacement Considerations

Direct functional substitutes within the same series include the ADR420AR (2.048 V), ADR423AR (3.00 V), and ADR425AR (5.00 V), provided the output voltage difference is acceptable for the circuit design. Cross-referencing should verify that the replacement maintains the required XFET noise characteristics and package compatibility.