In the above circuit the underlined IC AD8606 is getting heated up. At the node marked (low pass filter output) the current is high when i checked in ADIsimPE simulation software. how can this problem be overcomed?
How is your circuit coming along so far? I think it would be easy for you to just maintain your original schematic and replace the AD8606 parts with any one of these: ADA4610-2 (Dual), ADA4610-4(Quad) and ADA4000-4(Quad). These parts really suits to your application.
Let me know if you need anything else.
Do you have an assembled circuit for this? One thing I noticed on your schematic is that you are using the AD8606 with a +/- 5V supply. This parts are only specified with a absolute maximum supply voltage of 6 V as shown below.
If you need parts with higher supply voltage, I might give you a better recommendation. But yout have to tell me more about your applications. What is this circuit for? What is your desired bandwidth? What push you to use the AD8606 for this application?
Thank you for your reply.
I m using this circuit for detecting EMG signals through surface electrodes. The amplitude of EMG signals is less than 10mV. The useful signal is in the bandwidth of 20-500Hz. In order to avoid line noise i have put a high pass filter of 100Hz. I want to rectify and smoothen the signal and feed it to analog microcontroller ADuCM360 to do further processing.
can u suggest any alternative to AD8606?
We actually have several sample circuits for ECG applications and I will recommend the one on the AD8220's datasheet on Figure 67, page 25. You can do the same to use the AD8606 on a single supply 5 V operation. You just have to induce an offset voltage to make the signal within the input range of the amplifier.
I would like you also to double check the connection of C1 (10n) and R2 (!50K). What are you trying to do with that?
I strongly recommend to use the AD8220 sample ECG circuit design as a guide on your current circuit and let me know if you encountered any other problem..
Here C1(10n) and R2(150K) are used a high pass filter of 100Hz.
In the ECG Circuit you have suggested, if i change the cutoff frequency to match EMG signals will it work? Anyways I will try out he circuit and let you know the result.
Thanks for ur help.
If you want to create a high pass filter using the C1 and R2, then I think the connection of the node mark as "hp_filter" should be transfer to the node between the C1 and R2. Please refer to the sample schematic of figure 67 on the AD8220 datasheets particularly the 4.7 uF and 1 Mohms.
Yes, please be guided with the suggested schematic and adjust the gain and filter frequency depending on your design requirements.
I realized that the C1 and R2 was used for DC blocking before the rectifier circuit.
I tried out the ECG circuit with necessary changes but the amplitude of the signal was very small. If i put an non inverting opamp the signal was getting attenuated. So i tried the original circuit replacing AD8606 with OP2177 and it is working as expected.
Thanks a lot for your help
Glad to hear that it is now working! What makes you decide to use the OP2177? I've looked the OP2177 product page and I noticed that the ADA4077-2 is recommended as a new alternative parts for this. I am just curious on how you pick this parts.
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