Application Solution for the GX1258 (Replacing ADS1258) 12-Lead ECG Data Acquisition Module

Currently, the use of compact, portable ECG machines is increasing. This paper primarily introduces a high-performance, portable miniature 12-lead ECG signal digital acquisition module. The solution employs precision, low-drift, low-power components and utilizes a high-resolution analog-to-digital converter (ADC) for data acquisition. It achieves the acquisition, conversion, and transmission of 12-lead high-sampling-rate ECG signals through a simplified circuit design, thereby enhancing product performance and reliability.

The ADC in the solution performs digital ECG signal acquisition within the circuit. Its parameters and performance metrics directly impact the circuit complexity and sampling rate. ECG signals are weak bioelectric signals with amplitudes typically ranging from 0.05 to 5 mV. Therefore, to achieve synchronous amplification and conversion of 8-channel ECG signals, the ADC GX1258 (replacing ADS1258) is an ideal choice.

During ECG signal acquisition, various noise interference signals often contaminate the signals, with significant impacts including power frequency interference, polarization voltage interference, and baseline drift. Therefore, conventional ECG machines typically use 24-bit ADCs and incorporate corresponding signal conditioning circuits to process the signals before conversion. The GXSC GX1258 is a 16-channel (multiplexed), low-noise, 24-bit ADC that can stably acquire ECG data at a channel scanning rate of 1.8k to 23.7k in channel polling mode.

The GX1258 operates on a single +5V power supply, with a digital voltage range of 2.7V to 5.25V, and is packaged in a QFN-48 package.

Key Features:

• Fixed channels or channel polling; fixed channel data rate: 125kSPS

• Channel polling rate: 23.7kSPS per channel

• 16 single-ended or 8 differential inputs  

• Single-ended (+5V) operation  

• Low noise: 2.8 μVRMS at 1.8 kSPS  

• 0.0003% integration nonlinearity  

• DC stability (typical): 0.02 μV/°C offset drift, 0.4 ppm/°C gain drift

• Sensor open-circuit detection

• Conversion control pin

• Multi-output for external signal processing

• On-chip temperature, reference, offset, gain, and power supply voltage readback

• 42mW power consumption; standby, sleep, and shutdown modes

• 8 general-purpose input/output (GPIO) pins

• 32.768kHz crystal oscillator or external clock