AD7671ASTZ High-performance Analog-to-Digital Converter In-depth Analysis

1. One-sentence Description

The AD7671ASTZ is a 16-bit high-speed analog-to-digital converter (ADC) powered by a single power supply. It supports a wide input range from ±10V to 0V to 2.5V, integrates true bipolarity, low-power mode, and flexible serial and parallel interfaces, and is specifically designed for high-precision scenarios such as industrial control and instrumentation.

2. Core Features

• Ultra-high-speed Conversion:
  • Warp mode: 1 MSPS (million samples per second)
  • Normal mode: 800 kSPS
  • Impulse mode: 666 kSPS (power consumption is proportional to throughput)
• Ultra-high Precision:
  • Integral Nonlinearity Error (INL): ±2.5 LSB (maximum)
  • No missing codes (16-bit full resolution)
  • Signal-to-Noise Ratio (SNR): 90 dB (250 kHz input)
• Wide Input Range:
  • Bipolar: ±10V, ±5V, ±2.5V
  • Unipolar: 0V to 10V, 0V to 5V, 0V to 2.5V
• Multi-interface Compatibility:
  • Parallel interface (8/16-bit)
  • Serial interface (SPI/QSPI/MICROWIRE/DSP compatible)
• Low-power Optimization:
  • Impulse mode power consumption is only 15μW (100 SPS)
  • Typical power consumption is 112 mW (1 MSPS)

3. Core Technical Specifications

4. The Story Behind the Chip

The AD7671ASTZ is the technical crystallization of Analog Devices (ADI) in the field of precision data conversion. With the rapid development of Industry 4.0 and the Internet of Things, the demand for high-speed, high-precision, and low-power ADCs is increasing. Based on ADI's mature charge redistribution SAR architecture, the AD7671ASTZ achieves true bipolar input and dynamic power management through innovative design, solving the power consumption contradiction of traditional ADCs in wide input range and high-speed scenarios. Its previous products, AD7665/AD7664, have been verified in the market for many years, and the AD7671ASTZ further enhances the performance, making it an ideal choice for high-precision data acquisition systems.

5. Design Concepts

• Balance between High Speed and Precision: Adopting a 16-bit no missing code SAR architecture, combined with a high-speed comparator and an optimized DAC capacitor array, to ensure precision under high-speed conversion.
• Flexibility and Compatibility: Supports multiple input ranges and interface modes to adapt to different system requirements.
• Low-power Innovation: The Impulse mode adjusts power consumption and throughput dynamically to extend battery life; the single power supply design simplifies the circuit complexity.
• Anti-interference Ability: Built-in ESD protection, high common-mode rejection ratio (CMRR), and a low-noise front-end to adapt to the challenges of industrial environments.

6. Application Scenarios

• Industrial Automation: Motor control, PLC data acquisition
• Medical Equipment: Electrocardiogram (ECG), blood analyzers
• Instruments and Meters: Oscilloscopes, signal generators
• Energy Monitoring: Power system harmonic analysis, photovoltaic inverters
• Communication Equipment: Base station signal processing, radar systems

7. Unique Advantages

• True Bipolar Input: Can handle ±10V signals without external circuits, reducing system costs.
• Impulse Mode: Leading dynamic power management in the industry, with a power consumption of only 15μW at 100 SPS.
• High Anti-interference Design: The input filter (-3 dB bandwidth 9.6 MHz) effectively suppresses high-frequency noise.
• Seamless Upgrade: Pins are compatible with AD7665/AD7664, facilitating the iteration of existing systems.

8. What Engineers Need to Know When Selecting

• Input Range Configuration: Select the voltage range by connecting the INA/B/C/D pins (for example, connect IND to VIN and INC to INGND for ±10V).
• Interface Selection:
  • Parallel mode: Suitable for high-speed data transmission, pay attention to the configuration of the BYTE SWAP pin.
  • Serial mode: Reduces pin occupation and supports 3V/5V logic levels.
• Power Consumption Optimization:
  • The Impulse mode is suitable for low-frequency sampling, and the Warp mode is for high-frequency scenarios.
  • Turn off unused interfaces (such as setting SER/PAR to low to disable the serial interface).
• Reference Voltage Design:
  • The external reference voltage range is 2.3V to AVDD-1.85V, and low-noise reference sources such as ADR421/AD780 are recommended.
  • The reference capacitor (1μF ceramic + 10μF tantalum capacitor) should be close to the REF pin.
• Layout and Wiring:
  • Connect the analog and digital grounds at a single point to avoid cross-interference.
  • The CNVST signal requires low jitter, and an RC filter or a dedicated clock source is recommended.

Conclusion

The AD7671ASTZ, with its excellent speed, precision, and flexibility, becomes the core component of high-precision data acquisition systems. Whether in the harsh environment of industrial fields or the precise measurement of medical equipment, it can provide reliable solutions. When designing, engineers should focus on input configuration, power consumption mode, and interface selection to fully leverage its performance advantages.