ADS1299: Extra caps for EMC and Paitent protection resistor value

Faisal Almesfer

Part Number: ADS1299

Hello,

I recently had a pcb designed with an ADS1299 and I have a few questions around some of the design decisions:

1. In addition to the recommended datasheet layout, an extra 1nf cap (C11) is added to the bias circuitry. The designer mentioned this will help with EMI suppression. Is there any harm to keeping this cap on the pcb?

2. In addition to the recommended datasheet layout, an extra 100nf cap (C18) is added to VCAP1. The designer mentioned this will help with EMI suppression. Is there any harm to keeping this cap on the pcb?

3. The designer has selected 2.2 kohm as the value for the patient protection resistor. Will this suffice? What is the recommended resistor value?

Thank you,

Faisal

over 4 years ago

0 Alexander Smith over 4 years ago

TI__Guru 52492 points

Hi Faisal,

Thanks for your post and welcome to the forum!

I certainly see no problem with keeping the EMI suppression caps on the PCB. If you are not concerned about suppressing EMI, removing them should be fine as well - however it may lower the quality of the measurements being taken.

2.2kohm would be the recommended resistor value. Sizing this resistor depends on the particular standards for the market that end equipment will be sold into.

0 Faisal Almesfer over 4 years ago in reply to Alexander Smith

Prodigy 80 points

Hi Alex,

Thank you for your reply.

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ADS1299: Extra caps for EMC and Paitent protection resistor value