AD7714YRU: High-Performance 24-Bit Sigma-Delta ADC for Precision Applications

The AD7714YRU is a premium 24-bit sigma-delta analog-to-digital converter (ADC) developed by Analog Devices Inc., a global leader in precision integrated circuits. Despite being marked as obsolete, this IC remains highly sought after for its exceptional accuracy, robust performance, and versatility in demanding measurement applications. This comprehensive guide explores its technical specifications, unique features, and practical applications to help engineers evaluate its suitability for their projects.

In-Depth Technical Specifications

The AD7714YRU belongs to Analog Devices' renowned data converter family and offers these key specifications:

• Resolution: True 24-bit with no missing codes
• Architecture: Sigma-delta ( - ) with integrated digital filter
• Sampling Rate: Programmable up to 1 kSPS
• Input Channels: Configurable for 3 single-ended or 5 pseudo-differential inputs
• Input Voltage Range: 10mV to 2.5V (depending on gain setting)
• Programmable Gain: 1 to 128 in binary steps
• Interface: SPI/QSPI/Microwire compatible serial interface
• Power Supply: Single +3V or +5V operation
• Package: 24-lead TSSOP (Thin Shrink Small Outline Package)

Advanced Features and Benefits

Sigma-Delta Conversion Technology

The AD7714YRU utilizes sigma-delta modulation combined with a sophisticated digital decimation filter to achieve outstanding performance characteristics:

• Ultra-low noise: 1.5 V RMS noise at 19.5Hz update rate
• Excellent linearity: 0.0015% typical INL (Integral Non-Linearity)
• High rejection: 50Hz/60Hz noise rejection >100dB
• Automatic calibration: Background calibration mode maintains accuracy

Flexible Input Configuration

The device's input multiplexer supports multiple measurement configurations:

• Single-ended mode: 3 fully independent channels
• Pseudo-differential mode: 5 channels with common reference
• True differential mode: 2 fully differential pairs

This flexibility makes the AD7714YRU ideal for systems requiring measurement of multiple sensor types, including:

• Strain gauges and load cells
• Thermocouples and RTDs
• Pressure sensors
• Current shunt measurements

Integrated Programmable Gain Amplifier

The on-chip PGA provides these advantages:

• Gain settings: 1, 2, 4, 8, 16, 32, 64, 128
• High input impedance: >1G
• Rail-to-rail input: Handles signals near supply rails
• Low drift: <0.5 V/ C offset drift

Detailed Applications

Industrial Process Control

The AD7714YRU excels in harsh industrial environments for:

• PLC (Programmable Logic Controller) analog input modules
• Process variable monitoring (temperature, pressure, flow)
• Motor control current sensing
• 4-20mA loop monitoring

Medical Instrumentation

Medical applications benefit from its precision:

• Patient monitoring equipment
• Diagnostic ultrasound systems
• Portable medical devices
• Laboratory analyzers

Test and Measurement

Scientific applications include:

• Precision weigh scales
• Material testing equipment
• Environmental monitoring
• Spectroscopy systems

Design Considerations

Reference Voltage Selection

For optimal performance:

• Use low-noise, low-drift references like the ADR421 (2.5V) or ADR441 (4.096V)
• Maintain reference stability with proper decoupling (10 F tantalum + 0.1 F ceramic)
• Consider ratiometric configurations for bridge sensors

PCB Layout Guidelines

Critical layout practices:

• Separate analog and digital ground planes
• Use guard rings for high-impedance inputs
• Minimize trace lengths for reference and input signals
• Implement proper power supply decoupling

Alternative and Complementary Components

For designers considering alternatives or companion parts:

• Higher-speed ADCs: AD7768 (24-bit, 256kSPS)
• Lower-power options: AD7124-4 (24-bit, ultra-low power)
• Reference ICs: ADR4525 (ultra-low noise 2.5V reference)
• Signal conditioners: AD8237 (instrumentation amplifier)

Conclusion

The AD7714YRU remains an excellent choice for precision measurement applications despite its obsolete status. Its combination of 24-bit resolution, flexible input configuration, and robust performance continues to make it valuable for:

• Legacy system maintenance
• High-accuracy designs where newer parts may not be suitable
• Applications requiring proven reliability

Engineers can still obtain the AD7714YRU through authorized distributors with guaranteed quality and traceability. For new designs, Analog Devices offers migration paths to their latest generation sigma-delta ADCs with enhanced features.

When absolute precision matters, the AD7714YRU delivers performance you can trust. Contact our technical team today to discuss how this converter can solve your measurement challenges.