GXSC AFE Replaces ADS1291 in Widely Used Lumbar Massagers

Lumbar muscle strain has become a common health concern for modern people. Lumbar massagers have evolved from early models that relied solely on vibration and airbag compression to portable devices that integrate EMS bioelectric pulses, smart sensing, and long-lasting relief. The new generation of smart lumbar massagers no longer focuses solely on “high intensity”; instead, they emphasize adapting to the body’s muscle condition, precise stimulation, and comfortable wear. These features rely on a high-performance, low-power bioelectric signal acquisition and processing chip.

GXSC’s 24-bit, 32 kSPS bioelectric analog front-end chip offers a 100% hardware and software replacement for TI’s ADS1291. It captures real-time surface electromyography (EMG) signals from core muscle groups such as the quadratus lumborum and erector spinae, converting faint analog signals into high-precision digital signals to identify muscle fatigue levels, tense areas, and contraction states. Based on this data, the system automatically selects the appropriate massage mode, pulse intensity, and waveform. This chip integrates a full suite of functions including signal acquisition, amplification, filtering, and conversion, with specifications highly optimized for the close-contact usage scenarios of lumbar massagers.

EMG signals typically have low amplitude, and capturing their minute waveforms requires a system with high resolution and low noise. The GXSC AFE features 24-bit high resolution and employs advanced low-noise design. Its internally integrated programmable gain amplifier (PGA) and digital filter effectively suppress noise interference.

For wearable applications, the GXSC AFE offers an ULP mode with a power consumption of just 0.475 mW per channel, significantly extending battery life. Its data buffering function reduces the number of MCU interrupts, helping to conserve system power. It also features lead detection based on a current sink/current source, with a current range of 6 nA to 399 nA, which can be adjusted according to product requirements. Its key features are as follows:

• Data rate: 31.25 SPS to 32 kSPS

• Programmable gain: 1, 2, 3, 4, 6, 8, or 12

• Ultra-low input reference noise: 4.07 μVpp (0.64 μVrms) (BW = 150 Hz, G = 6)

• CMRR: 120 dB

• Flexible power modes: High-Speed (HS), Low-Power (LP), and Ultra-Low-Power (ULP)

• In Low-Power mode, power consumption is only 410 µW (AVDD = 3 V, DVDD = 1.8 V, ODR = 500 SPS, G = 6)

• Built-in low-drift reference; built-in clock with adjustable frequency and external output capability

• Built-in right-lead drive amplifier, lead disconnection detection, temperature sensor, and test signal

• Supports digital pacing detection

• Adjustable data buffer depth (1/2/4/8/16/32)

• Offset/Gain error calibration

• Power supply range: Analog power supply: 2.7V to 5.25V; Digital power supply: 1.8V to 5.25V

• Flexible power-down and standby modes

• SPI interface

• Operating temperature range: -40°C to +85°C