GXSC Analog Front-End Replacement for ADS1291 in Sports Watches

Major manufacturers of wearable fitness devices are continuously improving the functionality and design of next-generation smartwatches, including features like heart rate monitoring, more sophisticated algorithms, extended battery life, and slimmer, more lightweight appearances, thereby delivering a more refined user experience.

The physiological monitoring module of a sports watch must achieve precise acquisition of weak physiological signals within limited space and power consumption, while resisting electromagnetic interference and signal noise during physical activity. The GXSC low-power, single-channel, 24-bit analog-to-digital converter is an analog front-end chip specifically designed for portable medical and sports health devices, capable of pin-to-pin replacement of the ADS1291 and fully meeting the stringent requirements of sports watches.

The GXSC analog front-end is specifically designed for bioelectric potential measurements, supporting 24-bit high resolution to achieve fine quantification of weak biological signals. With advanced low-noise design, it features an integrated programmable gain amplifier (PGA) and digital filter, effectively suppressing noise interference.

For portable battery-powered sports watches, the GXSC analog front-end chip offers an ULP mode, significantly extending battery life. Its data caching function reduces MCU interrupt frequency, helping to minimize system power consumption. Therefore, adopting this chip can greatly reduce the size, power consumption, and cost of application products. Additionally, it features lead detection based on excitation current well/current source, with a current range of 6nA to 399nA, allowing for flexible adjustment according to product requirements.

The main features of the GXSC analog front-end chip 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: 4.07μVpp (0.64μVrms) (BW=150Hz, G=6)

• CMRR：120dB

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

• Low power mode with power consumption as low as 410µW (AVDD=3V, DVDD=1.8V, ODR=500SPS, G=6)

• Built-in low-temperature coefficient reference; internal clock with external output capability and adjustable frequency

• Built-in right leg drive amplifier, lead-off detection, temperature sensor, test signal

• Supports digital pacing detection

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

• Offset/Gain error calibration function

• Power Supply Range: Analog Power Supply: 2.7V to 5.25V; Digital Power Supply: 1.8V to 5.25V

• Flexible power-off and standby modes

• SPI interface

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