Medical-grade 12-lead ECG solution based on Lixin LH001-91
1. Introduction to LH001-91
1.1. Structure diagram
Figure 1. LH001-91 Structure Diagram
Low Noise Programmable Gain Amplifier (PGA) and High Resolution 24-Bit Analog-to-Digital Converter (ADC)< /section>
Built-in oscillator and reference voltage
Built-in integrated excitation current source
4-wire SPI interface
Operating temperature range: -40°C ~ +85°C
40 pins, 5mm x5mm QFN package
30 pins, 2.95mm x2.95mm WLCSP package
2. Measurement principle
The reason why blood can circulate continuously in the human body is because the human heart continues to excite and contract regularly. The excitation of the sinoatrial node causes the heart to beat. The excitation here refers to the result of the joint action of depolarization and repolarization of cardiomyocyte electrical activities. The figure shows the schematic diagram of the depolarization and repolarization process of cardiomyocytes. Cardiomyocytes are stimulated to cause positive charges outside the cell membrane to flow into the cell, making the inside of the cell membrane a positive potential and the outside of the cell membrane a negative potential. This process is called the depolarization process. Due to cell metabolism, the state of charge inside and outside the cell is slowly restored to the polarized state. This restoration process is called the repolarization process. Excitement is transmitted from the sinoatrial node to the atrium and ventricle in turn, so that the potential difference of the entire heart area is exposed to a continuously changing state, thereby generating a regularly changing current.
Figure 2. Schematic diagram of myocardial depolarization and repolarization
3. Program introduction
Figure 3. Scheme block diagram
Figure 4. Electrode position map
12-lead signal, 8 of which are generated by LH001-91 conversion, the specific configuration method is as follows.
The other 4 lead signals are obtained indirectly through calculation according to the table below.
The picture below is the actual picture of the customer's demonstration board connected to the ECG simulator. Linghui Lixin can provide a full set of Demo board and host computer software.
Figure 5. Demo board physical picture
The demo board collects the ECG simulator signal under the condition of computer USB power supply, and draws the ECG as shown below, the signal does not pass through Any external filter processing, fully meet the medical needs.
Figure 6. 12-lead ECG waveform
The chip used in the above measurement scheme has its own internal reference voltage, the input noise is 2.9 μVpp (250 SPS, gain 6), the common mode rejection ratio ( CMRR) 117dB, integral non-linearity 2 PPM/FS, 24-bit high-precision ADC, support lead continuous disconnection detection, low-temperature drift programmable gain amplifier medical grade domestic ECG AFE products, sufficient supply and reasonable price, which is also It is the advantage of domestic chips.