The Best Choice of the ECG Patch Technology Scheme

LH001-91, launched by Legendsemi, is a medical-grade analog front end specially developed for ECG signal acquisition, which integrates 24-bit ΣΔADC, programmable gain amplifier, 150 Hz in-band noise of 3 μVpp, and AFE with right leg driving, conductive shedding monitoring and other functions. The product has excellent performance indexes, including input reference noise of 2.9 μVpp, common mode rejection ratio of 117 dB and internal reference temperature excursion of 16 ppm/℃; the static power consumption is 0.1 μW, and all the core indexes have reached the level of international brands. Furthermore, the overall performance is better than that of similar products of international manufacturers, and it has been professionally evaluated by domestic medical customers. At present, it is a domestic chip that can rarely pass the medical test in China. The domestic high-precision signal chain products are expected to enter the medical field, ending the monopoly of European and American brands.
Recommended chip: LH001-91
The Best Choice of the ECG Patch Technology Scheme

LH001-91: The most technical scheme of electrocardiogram sticking Good choice

EKG patch is an effective means of monitoring cardiovascular disease
The "China Cardiovascular Health and Disease Report 2019" pointed out that the number of people with cardiovascular diseases has reached 330 million, and the trend is increasing year by year. For people with cardiovascular diseases, ECG monitoring is a guarantee service necessary for them to maintain their daily health, and it is also one of the inspection methods that can detect diseases in time. Long-term ECG monitoring can help doctors and patients to know the heart abnormalities in advance. Studies have shown that 72% of patients will have obvious discomfort before cardiac arrest, and 70% of patients have warning symptoms that last for more than 15 minutes. Real-time ECG monitoring can effectively reduce the serious consequences of cardiovascular and cerebrovascular diseases, and reduce disability and mortality.
The core requirement of heart monitoring is first of all accuracy, because the tiny electrical signals of the heart will have a lot of interference, and these interferences need to be eliminated to reflect the real heart condition. The second is timeliness. The onset of many diseases is sporadic and can be very severe suddenly. It is only meaningful to monitor during the onset. Otherwise, there will be situations where patients repeatedly go to the hospital and cannot be checked out repeatedly. Third, in real time, when a problem is found, the medical staff or patient can be notified immediately for treatment.
The electrocardiogram at the hospital is monitored for 30-60 seconds while the patient is lying on the hospital bed. Represented by Holter, 24-hour monitoring is carried out, electrodes are attached to the body, and wires are connected to small equipment. This kind of electrocardiogram equipment is relatively large in size and the patient feedback is relatively poor. Although 24-hour monitoring can be performed, the window period is relatively short. Unable to respond in a timely manner.
The medical patch-type electrocardiometer can achieve long-term monitoring of portable devices, and upload the data to the cloud platform in real time. The intelligent big data algorithm can monitor various arrhythmias. Once the algorithm finds a problem, it will be prompted, and the expert will be contacted through the telemedicine platform, and the doctor will give specific professional advice. After the doctor corrects it, it will output a diagnostic analysis report and provide pre-clinical diagnosis and analysis.

Figure 1. ECG sticker scheme

LH001-91 ECG patch program
The LH001-91 launched by Linghui Lixin is a medical-grade analog front-end specially developed for ECG signal acquisition. It integrates 24-bit ΣΔ ADC, programmable gain amplifier, 150Hz in-band noise 3μVpp, including the right leg AFE with functions such as drive and conduction shedding monitoring. The performance indicators of the product are superior, among which the input reference noise is 2.9 μVpp, the common mode rejection ratio is 117dB, the internal reference temperature drift is 16ppm/℃; the static power consumption is 0.1μW, and all the core indicators have reached the level of international brands, even the overall The performance is better than the same type of products of international manufacturers, and it has been professionally evaluated by domestic medical customers. It is currently one of the few domestic chips that can pass medical tests in China. The domestic high-precision signal chain products are expected to enter the medical field and end the monopoly of European and American brands.
Figure 2 is the evaluation board of LH001-91, which is mainly composed of AFE (LH001-91), general-purpose MCU and three electrodes on both sides. Lixin also provides a full set of software demonstration solutions. Figure 3 is the real-time waveform of the electrocardiogram obtained based on the evaluation board of Lixin. The ECG features are obvious and meet medical-grade applications.

Figure 2. ECG customer evaluation board


Figure 3. ECG measured based on the ECG demo board Waveform diagram

In addition, LH001-91 can also be used for ECG watch, ECG bracelet, ECG meter, hand-held ECG Products such as monitors and brain wave acquisition systems, Figure 4 shows the form of terminal products of some customers.

Figure 4. Other extensive application examples

Since LH001-91 was supplied in batches, it has been adopted by more than 20 customers and applied to new product development. Some customers have entered the mass production stage, with shipments of nearly one million. At present, leading customers in the medical industry are testing LH001-91, and the evaluations given are very positive. A medical customer in Shenzhen even expressed excitement that finally a domestic ADC can achieve such performance, making the customer more confident in domestic signal chain products. Interested friends can contact our marketing staff for evaluation boards and samples.

Key indicators for LH001-91
Low Noise Programmable Gain Amplifier (PGA) and High Resolution 24-Bit Analog-to-Digital Converter (ADC)
−  Programmable gain: 1/2/4/6/8/12/24/48
−  4 differential inputs or up to 8 single-ended inputs
−  Integral nonlinearity: 2 PPM/FS
Electrocardiogram/electroencephalogram measurement (ECG/EEG)
−  Input referred noise: 2.9 μVpp (250 SPS, gain 6)
−  ECG channel input bias current: 200pA
−  Data Rates: 125SPS to 8kSPS
−  Common Mode Rejection Ratio (CMRR): 117dB
−  Measuring current: 288μA
−  Built-in right leg drive amplifier, continuous disconnection detection, test signal
−  Integrated temperature sensor
Built-in oscillator and voltage reference
Standby mode
−  Current 0.1 μA
−  Analog: 2.4V to 3.6V
−  Digital: 1.7V to 3.6V
4-wire SPI interface
Operating temperature range: -40°C ~+85°C
−  5mm x5mm QFN 40 feet
−  2.95mm x2.95mm WLCSP 30 pins (LH001-91/99 support small package)