NAU7802 24-bit ADC Datasheet, Features, Pinout, and Applications

The NAU7802 is a high-performance, low-power, 24-bit analog-to-digital converter (ADC) designed for precision measurement applications. Manufactured by Nuvoton Technology, the NAU7802 integrates a low-noise amplifier, making it ideal for applications such as load cells, weigh scales, and medical instrumentation. Its compact design and power efficiency make it suitable for battery-operated devices and portable systems.

Overview of NAU7802

The Nuvoton NAU7802 is a low-power, high-precision 24-bit analog-to-digital converter (ADC) featuring an integrated low-noise programmable gain amplifier (PGA), onboard RC or crystal oscillator, and a high-precision 24-bit sigma-delta (Σ-Δ) ADC. This device delivers up to 23-bit effective number of bits (ENOB) performance, offering a complete front-end solution for applications such as weigh scales, strain gauges, and other high-resolution, low-sample-rate systems. Its built-in features allow for high-performance operation with minimal external components.

The NAU7802 is designed for low operating and standby currents, with several power management options to enable selective powering of essential chip elements. This allows for low-power operation, especially when full 23-bit ENOB performance is not required. The programmable gain amplifier (PGA) provides gain settings ranging from 1 to 128, while the ADC utilizes a Sigma-Delta modulator and programmable FIR filter. This setup includes a dual 50Hz and 60Hz notch filter to enhance immunity to interference effectively.

Additionally, the device supports a standard 2-wire interface, compatible with the I2C protocol, simplifying integration with a wide range of host processors for easy communication and system design.

NAU7802 Features

• Power Supply: 2.7V to 5.5V
• On-chip VDDA Regulator: Supports internal analog circuits or external load cells
  • Programmable VDDA: Options include of, or 2.4V to 4.5V in eight selectable settings
  • Minimum 10mA output drive capability at 3.0V output
  • Note: DVDD must be at least 0.3V higher than the desired VDDA output voltage
• 23-bit Effective Precision ADC
• 50Hz and 60Hz Rejection: Simultaneous rejection with up to -90dB effectiveness
• RMS Noise:
  • 50nV at 10 SPS output rate with PGA gain = 128
  • 150nV at 80 SPS output rate with PGA gain = 128
• Programmable PGA Gain: Ranges from 1 to 128
• Programmable ADC Data Output Rates
• External Differential Reference Voltage: Ranges from 0.1V to 5V
• System Clock Options:
  • External 4.9152MHz crystal oscillator
  • On-chip 4.9152MHz RC oscillator
• On-chip Features:
  • Calibration
  • Power-on reset circuit
  • Temperature sensor
• Low Power Consumption & Programmable Power Management:
  • Standby current: < 1uA
• External 4.9152MHz Crystal Oscillator
• MCU Control Interface: 2-wire interface, I2C protocol compatible
• Operating Temperature Range: -40°C to 85°C
• Package Options:
  • SOP-16 (150mil)
  • PDIP-16

NAU7802 Pinout

NAU7802 Pin Configuration

System Block Diagram

Absolute Maximum Ratings

NAU7802 Applications

Weigh Scales

The NAU7802 is widely utilized in digital weighing scales due to its precision and accuracy in converting load cell signals into readable data. It interfaces directly with load cells to measure weight and convert analog signals into digital output. This makes it essential for applications requiring high resolution and stability, such as personal scales, industrial scales, and medical weight measurement systems. Its low power consumption and ease of integration make it ideal for both portable and stationary weighing applications.

Strain Gauge

Strain gauges measure the deformation or strain of an object, and the NAU7802 plays a critical role in accurately processing the signals generated by these sensors. By amplifying the small voltage changes in the strain gauge, the NAU7802 allows for precise measurements of stress, displacement, or load applied to an object. This application is fundamental in structural health monitoring, material testing, and various force measurement systems, where precision and reliability are essential.

Industrial Process Control

In industrial settings, maintaining consistent and accurate process control is crucial for optimal operation. The NAU7802 is used in systems that monitor and control variables such as pressure, temperature, and force in manufacturing processes. By providing precise digital output from analog sensors like load cells and pressure transducers, it ensures real-time monitoring of critical parameters. Its integration in process control helps enhance automation, reduce downtime, and improve overall operational efficiency.

Liquid/Gas Flow Control

In systems designed to monitor and control the flow of liquids and gases, the NAU7802 ensures the accurate measurement of force or pressure exerted by the fluid. It is used in conjunction with flow meters and pressure sensors to convert mechanical measurements into digital signals, offering precise flow rate control. This is particularly important in industries like chemical manufacturing, water treatment, and gas distribution, where accurate flow regulation is critical for safety and performance.

Pressure Sensors

Pressure sensors rely on the NAU7802 to measure the force applied by a gas or liquid on a given surface. The IC amplifies the output from pressure-sensitive components like piezoelectric or resistive sensors, allowing for high-accuracy pressure monitoring. This application spans a wide range of industries, from automotive to medical devices, ensuring the safe and reliable operation of systems that require precise pressure measurements, such as hydraulic systems, fuel systems, and HVAC systems.

Voltage Monitors

Voltage monitoring is essential for ensuring that electronic systems operate within their specified voltage ranges. The NAU7802's precision makes it an ideal component in voltage monitoring applications, where it can monitor fluctuations in voltage levels and help protect sensitive equipment from overvoltage or undervoltage conditions. Its role in this application is to help safeguard electronic systems in power distribution units, battery management systems, and energy-efficient devices, maintaining stability and performance.

Application Circuit

16-pin Application Circuit

NAU7802 Package

The NAU7802 is available in 16L SOP – 150 mil and PDIP16L – 300 mil packages, offering compatibility with different PCB assembly techniques. The flexible package options ensure reliable operation in space-constrained designs or traditional setups.

• 16L SOP – 150 mil

• PDIP16L – 300 mil

NAU7802 Manufacturer

Nuvoton Technology, a global leader in semiconductor solutions, manufactures the NAU7802. Nuvoton is known for its innovative and reliable products, catering to industries ranging from consumer electronics to industrial automation.

NAU7802 Datasheet

The datasheet for the NAU7802 provides comprehensive details on electrical characteristics, pin configurations, and design guidelines. Engineers can use the datasheet to ensure optimal integration and performance in their systems.

NAU7802 vs. Other ADCs

• NAU7802 vs. HX711: The HX711 is another popular 24-bit ADC for weigh scales, but the NAU7802 offers better noise performance, a higher maximum sample rate, and an integrated temperature sensor.
• NAU7802 vs. ADS1232: The ADS1232 provides similar features but consumes more power compared to the NAU7802, making the latter a better choice for battery-operated systems.
• NAU7802 vs. MCP3421: While the MCP3421 is a low-cost 18-bit ADC, the NAU7802's higher resolution and integrated PGA make it more suitable for high-precision applications.

Popular NAU7802 ADCs

• NAU7802SGI
• NAU7802KGI

Conclusion

The NAU7802 ADC is a versatile and high-precision solution for applications requiring accurate signal measurement. Its integrated PGA, low power consumption, and compact design make it ideal for load cells, weigh scales, medical devices, and IoT systems. With its robust performance and ease of integration, the NAU7802 ensures reliable operation in demanding environments.

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