Eliminating Right leg drive in ADS1293

Harshit Balaraman

Other Parts Discussed in Thread: ADS1293EVM, ADS1293

Hi TI,

I'm Harshit, trying to measure lead 1 ECG signal using ADS1293EVM. Is it possible to get ECG by eliminating the Right leg connection either by shutting down RLD amplifier or by other means ?

over 10 years ago

0 Amy Schnoor over 10 years ago

TI__Mastermind 18285 points

Harshit,

I am moving your post to the Precision Data Converters Forum. They will be able to assist you.

0 Bahram Mirshab over 10 years ago in reply to Amy Schnoor

TI__Expert 3350 points

Yes, you can shut off the RLD amp. The RLD is a needed low impedance path between the patient body and the ADS1293. It act as a ground reference between the patient and the ADS1293 circuit. It is also used to reduced the common mode offset. If it is disconnected, the Lead-off detection feature will not work. Also as the electors are floating, you would have base-line wondering. My suggestion is to removed the RLD electrode, and connect the out put of the RLD amp internally to one of the electrodes in use.

Regards,

Bahram. Mirshab

0 Harshit Balaraman over 10 years ago in reply to Amy Schnoor

Prodigy 70 points

Amy, Thanks.

0 Harshit Balaraman over 10 years ago in reply to Bahram Mirshab

Prodigy 70 points

Hi Bahram,

Thanks for your reply, I did as you said. I removed the RLD electrode and connected the output of RLD to IN1(Right hand) internally using Right leg drive control register. But I got ECG data with interference, I have attached the plot of it.

0 Bahram Mirshab over 10 years ago in reply to Harshit Balaraman

TI__Expert 3350 points

Hi Harshit,

Have you connected the inputs to an ECG Emulator (test signal generator) or the signal is actually coming from electrodes connected to a body?

B. Mirshab

0 Harshit Balaraman over 10 years ago in reply to Bahram Mirshab

Prodigy 70 points

Hi B.Misrab

The electrodes were actually connected to the body.

The ECG from the Emulator (test signal generator) looked better. Why is this happening ? How can I solve this ?

0 Bahram Mirshab over 10 years ago in reply to Harshit Balaraman

TI__Expert 3350 points

Hi Harshit,

Probably you are using dry electrodes. If that is the case, there is a very high impedance between the body and the electronics. You need to use conductive jell ( Silver/Silver Chloride ) available for ECG application to lower the impedance between the surface of the electrodes and the body. Also, make sure to connect the electrodes to appropriate spots on the chest , as shown in the ADS1293 datasheet, for best results.

Regards,

Bahram Mirshab

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Eliminating Right leg drive in ADS1293