My questions to ADAS1000-4: a) Does ADAS1000-4 also work with only two electrodes e.g. LA and RL ? b) How does the respiration measurement (respiration-path) work and where do you have to connect the three outputs/inputs ? c) Does each ECG input channel an own high-pass filter? d) Can you configure/adjust the high-pass filter? e) What is the function of Shield Drive Amplifier? We want to connect the shields to GND. f) Could you send example source code written in C or C++ for ADAS1000-4? g) Can we provide a standard connection diagram?
a) The minimum number of electrodes required for ECG measurement would be 3, so 2 ECG electrodes, e.g. RA and LA and the RLD. This would give a one lead measurement. If RLD is not used, then the CMRR performance will degrade which will affect the quality of the ECG measurement. It really depends on what your customer is trying to do, the type of ECG instrument they are trying to develop. Note that an ECG measurement is always a pair of ECG electrodes, e.g. RA/LA…. Etc. b) The respiration measurement is made on a pair of electrodes (a lead). This pair of electrodes can be the ECG electrodes, e.g. LEAD I/II/III. Page 34 of the datasheet provides a detailed description but in summary a programmable high frequency differential current is driven out onto two electrodes and. The resulting impedance variation caused by breathing causes the differential voltage to vary at the respiration rate. The current is AC coupled onto the patient. There is a shallow modulation envelope that equates to the respiration frequency. RFI filtering, ESIS filtering in addition to the cable impedance will affect the ability to measure this small ohm variation in the presence of a large series resistance, Table 13 on the datasheet gives you the maximum allowable cable and thoracic loading. c) Low pass filtering is covered by the ADAS1000 (e.g. on chip 40Hz/150Hz/250Hz/450Hz) For HP (0.5Hz/0.05Hz) or Notch (50/60Hz) this would be something likely better done in the digital domain by yourself. d) See above. e) It is used to drive the shield of the ECG cables. It can be disabled if not used. f) There is in fact some ucontroller code available. This should provide some insight/starting point. Please take a look at http://wiki.analog.com/resources/tools-software/uc-drivers/renesas/adas1000 g) http://www.analog.com/static/imported-files/circuit_notes/CN0308.pdf In this circuit note there is a very useful connection diagram. It can be applied to the ADAS1000. Please also note that the evaluation board hardware is for use only for evaluation purposes, it was not designed to be connected to humans or animals. In terms of ADAS1000 configuration, it demonstrates the key elements in terms of decoupling and possible configuration for a 12-lead solution. However, please note it is not intended as a reference design. The component selection used on the evaluation board may not be suitable for end system use. The evaluation board schematic has not been tested against defib/esis signals. The end system design and component selection is the responsibility of the system integrator.
Hello 风玲 杜,
Can you provide part number of the crystal you are using?
Ideally the crystal will be close to the pins, but this is not always easy to achieve.
On my evaluation board, the crystal is also approx. 10mm distance from the pins, this was because I used a socket on the board initially so there was a keep out area.
First, I think the distance between my crystal and ADAS1000 is a little far.It is 10 millimeter.Is it the reason make crystal sit around 300mV.
Second,The circuit diagram of the crystal is shown below.Actually I don't add C29 and C30.Because if add the two capacitor,the amplitude of crystal is lower than 300mV,it is only 260mV.
Thank you for your attention to my question。
I use my own board.You see it is only 297mV.
Thanks for your question.
See attached plot from my board - I expect the crystal should be sitting around 450mV.
Are you using your own board or ADI evaluation board?