I bought AD8232 EVAL and checked ECG signal under the following configuration.
3 electrode connection
DC leads off detection
During measuring ECG signal on IAOUT and OP AMP OUT, there are random noise on both signals as the following pic. It looks like IA malfunction. Is it normal behavior for AD8232?
Actually the other ECG monitor solution which is used AD8237 and AD8607 has no problem under same condition.
Moreover there is a lot of hum noise (50/60Hz noise) on it too.
You could try doing the following and see if the noise goes away:
1. If you are not using batteries already, I would recommend using those to power up your board.
2. Try twisting the wires from your input source to the board (electrode wires or cables).
3. Put the PCB inside of a metal enclosure. You can put a piece of paper or something non-conductive on the bottom so that nothing shorts together on your board. You can then connect the system ground to the enclosure.
Give those a try first and let me know if it works.
Thank you for your advice above.
I will try those but I can not apply item3 (use a metal enclosure) because my product is enclosed by mold.
If item3 could be effective for my case, AD8232 is worse than AD8237 in terms of RFI, isn't it?
I tried item1 and 2. Those did not work at all.
I can not try item3 because we can not apply a metal enclosure.
Any other advice you have?
Do you have decoupling caps on your supplies? Could you provide a picture of your setup?
Yes, 0.47uF on LDO output and the others are all on the EVM board.
Actually now My AD8232 EVM board works with battery & LDO, so i think the power supply is very clean.
My setup is below.
Power Supply : Battery (1 Cell Li-ion) and LDO for 3.3V output.
AD8232 board : AD8232 EVAL
Electrode configuration : 3 electrodes (Right arm, Left arm and Right leg)
Feature settings : FR/ disable, Leads off mode/DC
Both electrodes pull up to VS
Any other clues you have for this issue?