AU6040
Complete signal conditioning for strain gauge and pressure sensors with integrated excitation and linearization.
Product Overview
Description
The AU6040 is a complete signal conditioner for bridge-type sensors including strain gauges, load cells, and pressure sensors. It provides integrated excitation, amplification, and linearization in a single device.
With programmable excitation voltage (2.5V to 5V) and gain (up to 128x), the AU6040 can interface with a wide range of bridge sensors. The 24-bit ADC provides high-resolution measurements with excellent noise performance.
Integrated linearization compensates for sensor non-linearity, improving accuracy over the full measurement range. The device supports both 4-wire and 6-wire bridge configurations for lead resistance compensation.
Product Series
AU
Primary Application
Weighing scales
Key Features
- Complete bridge sensor interface
- Programmable excitation voltage
- 24-bit high-resolution ADC
- Integrated linearization
- 4-wire and 6-wire support
- Low noise <1μV
Specifications
| ADC Resolution | 24-bit |
|---|---|
| Excitation Voltage | 2.5V to 5V |
| Gain Range | 1x to 128x |
| Input Range | ±80mV full scale |
| Accuracy | ±0.01% FS |
| Interface | SPI/I2C |
| Package | QFN-24 |
Applications
Weighing scales
Electronic system design
Pressure sensors
Sensor signal conditioning
Force measurement
Data acquisition and conversion
Torque sensors
Sensor signal conditioning
Industrial automation
Industrial automation and control
FAE Expert Insights
"The AU6040 is an excellent bridge sensor interface that I've used in weighing scale applications. The integrated excitation eliminates the need for external reference, saving BOM cost. The linearization feature is valuable - it can improve accuracy by an order of magnitude for some sensors. The 24-bit resolution gives plenty of dynamic range for high-precision scales. One tip: use the 6-wire configuration for long cable runs to eliminate lead resistance errors. Overall, a cost-effective solution for bridge sensor applications."
Complete bridge sensor interface with linearization and high-resolution ADC
— Michael Zhang, BeiLuo
Frequently Asked Questions
What sensors work with AU6040?
The AU6040 works with any resistive bridge sensor including: strain gauges (quarter, half, and full bridge), load cells (compression and tension), pressure sensors (absolute, gauge, differential), torque sensors, and force sensors. The programmable excitation and gain allow interfacing with sensors from 100Ω to 10kΩ bridge impedance.
Works with all resistive bridge sensors from 100Ω to 10kΩ impedance.
How does the linearization work?
The AU6040 includes polynomial linearization that compensates for sensor non-linearity. It supports 2nd and 3rd order correction based on sensor characterization data. You provide coefficients calculated from sensor calibration data, and the device applies correction in real-time. This can improve accuracy from ±1% to ±0.01% for typical strain gauges.
Use polynomial linearization with coefficients from sensor calibration.
What is the difference between 4-wire and 6-wire bridge connections?
The AU6040 supports both 4-wire and 6-wire bridge configurations: (1) 4-wire - standard connection with excitation and sense leads combined, suitable for short cable runs where lead resistance is negligible; (2) 6-wire - separate excitation and sense connections (Kelvin connection), eliminates lead resistance errors for long cable runs. Use 6-wire for applications with cable lengths over 3 meters or where lead resistance exceeds 1Ω. The device automatically compensates for lead resistance in 6-wire mode.
Use 4-wire for short cables; 6-wire for long cables (>3m) or high lead resistance.
How do I select the excitation voltage?
Excitation voltage selection depends on sensor specifications and power dissipation: (1) Higher voltage (5V) - better signal-to-noise ratio but higher sensor self-heating; (2) Lower voltage (2.5V) - lower power dissipation but reduced signal level; (3) Consider sensor power rating - ensure P = V²/R does not exceed sensor limits; (4) Balance between accuracy and self-heating. For strain gauges, 2.5V is typically sufficient. For pressure sensors, use the manufacturer's recommended excitation voltage.
Use 2.5V for strain gauges; follow sensor manufacturer recommendation for pressure sensors.
What gain setting should I use?
Gain selection depends on sensor output and desired resolution: (1) Calculate expected sensor output at full scale (typically 1-3mV/V for strain gauges); (2) Determine desired ADC input range (±80mV full scale at the device); (3) Gain = Desired ADC range / Sensor output; (4) Use the highest gain that keeps the signal within ADC range; (5) Consider noise - higher gain amplifies noise as well. Example: For 2mV/V sensor with 5V excitation (10mV output), use gain of 8x for ±80mV range.
Use highest gain that keeps signal within ±80mV ADC range.