Replacing the AD7380 with the GXSC ADC for Position Feedback in Motor Control

Position feedback devices for motor control are an indispensable component of servo systems. They measure the angle or position of the motor rotor in real time and feed this information back to the controller, thereby enabling precise control of the motor’s motion.

Currently, high-precision servo systems commonly use sine-cosine analog encoders to achieve ultra-high-resolution position detection; however, analog encoders place stringent demands on the sampling system, requiring dual-channel, strictly synchronized, high-speed, high-linearity, and low-noise analog-to-digital conversion capabilities. Traditional single-channel time-division sampling ADCs suffer from timing deviations. This solution recommends using GXSC’s four-channel 16-bit synchronous sampling analog-to-digital converter to replace the AD7380 in motor control position feedback applications.

The GXSC ADC offers key advantages such as an ultra-high throughput rate of 4 MSPS, fully differential inputs, on-chip oversampling for noise reduction, and a wide common-mode voltage range, making it ideal for motor position feedback and high-speed precision measurement and control applications. Its differential analog inputs support a wide common-mode voltage range, and sampling and conversion are triggered by the falling edge of the chip select signal. This significantly improves the static positioning accuracy and low-speed running stability of servo systems.

The GXSC ADC integrates an on-chip oversampling module that effectively expands the dynamic range and reduces input noise in low-bandwidth applications. When the oversampling function is enabled, it can be configured for 18-bit high-precision mode. The voltage range of the reference input pin is 2.5 V to 3.3 V. The conversion process and data acquisition are implemented through a standardized control interface, facilitating integration with microprocessors or digital signal processors. Conversion results support two output modes: 1-wire serial output mode (suitable for low-speed applications) or 4-wire synchronous output mode (suitable for high-sampling-rate applications).

GXSC ADC Features:

• SNR: Typical value of 91.5 dB (VREF = 3.3 V)

• INL: Typical value of +1

• On-chip oversampling

• Supports 18-bit high-precision mode

• Out-of-threshold alarm indication

• High-speed serial interface

• QFN24 4 mm × 4 mm package

• Operating temperature range: −40°C to 125°C

• Supports 1.8 V, 2.5 V, and 3.3 V independent logic power supply interfaces