GXSC ADC Replaces AD7685 in Motor Control Systems

Industrial motor control systems achieve precise control of motor speed, torque, and position through the synergy of hardware and control algorithms. Modern industrial motor control systems take current/voltage monitoring, speed regulation, and fault diagnosis as their core control logic, relying on high-precision analog signal sampling to implement vector control, SVPWM modulation, and dynamic parameter correction.

Traditional motor control solutions commonly use the AD7685 for analog signal acquisition. The GXSC single-channel, 16-bit, 250 kSPS analog-to-digital converter can serve as a drop-in replacement for the AD7685 in both hardware and software, while also offering a certain cost advantage. This GXSC ADC also features a low-noise, wide-bandwidth, short-aperture-delay track-and-hold circuit. On the rising edge of CNV, it samples the analog input IN+ against ground-sensed input IN–, within a range of 0 V to REF. The reference voltage REF is externally supplied and can be set up to the supply voltage. Power consumption scales linearly with throughput.

High precision and speed combined: Delivers true 16-bit resolution while maintaining excellent linearity at sampling rates up to 250 kSPS. Its integral nonlinearity (INL) is typically only ±0.6 LSB (maximum ±2 LSB), equivalent to ±0.003% of full scale, ensuring conversion accuracy.

Superior dynamic performance: Achieves an SNR of 82 dB and a total harmonic distortion (THD) as low as –100 dB at a 20 kHz input frequency, making it ideal for applications requiring high-fidelity signal acquisition.

Flexible pseudo-differential input: Employs a pseudo-differential input architecture with an input range spanning 0 V to REF, where the reference voltage REF can be externally set (up to the supply voltage VDD). This design provides the common-mode noise rejection benefits of differential inputs while simplifying single-ended signal interface design.

GXSC ADC Key Features:

16-bit resolution with 250 kSPS throughput

Integral nonlinearity (INL): ±0.6 LSB typical

Signal-to-noise-and-distortion ratio (SINAD): 93.5 dB at 20 kHz

Total harmonic distortion (THD): –110 dB at 20 kHz

Pseudo-differential analog input range: 0 V to VREF, with VREF up to VDD

No pipeline delay

Single-supply operation: 2.3 V to 5.5 V, with 1.8 V to 5 V logic interface

Proprietary serial interface: compatible with SPI, QSPI, MICROWIRE, and DSP

Power consumption: 7.4 μW at 2.5 V / 100 SPS, 1.35 mW at 2.5 V / 100 kSPS, and 4 mW at 5 V / 100 kSPS

Standby current: 1 nA

10-lead MSOP package