ADS1298R: ADS1298R Schematics Review

Nivethitha D

Part Number: ADS1298R
Other Parts Discussed in Thread: ADS7042

Hi,

Kindy find the ADS129XR Design and provide your review comments. Currently this is designed for 5 leads in future it is expected to use also for 12 lead. But how to route use 12-Lead ECG as well as Respiration rate measurement in schematics?

Respiration circuit is given as per the Figure 97. Typical Respiration Circuitry in the datasheet. But when this is used, I cannot use one channel-lead V2?

Please provide your comments for the above

ECG Connector end

over 1 year ago

0 ChienChun Yang over 1 year ago

TI__Mastermind 19815 points

Hi,

It will take several days to do schematic review.

In the meantime, could you compare your schematic with the ADS1298R schematic in the EVM's user guide.

Thanks

0 Nivethitha D over 1 year ago in reply to ChienChun Yang

Intellectual 370 points

Sure, kindly let me know the review comments mean while. Thanks

0 Praveen Aroul over 1 year ago in reply to Nivethitha D

TI__Mastermind 49916 points

Hello Nivethitha,

ADS1298R supports 7 channels for ECG and 1 channel for respiration.

To support 12 Lead ECG with respiration, you will need to use multiple ADS129x device.

With regards to schematics, VCAP1 should be connected to 22uF to VSS.

Connect a 10uf and 0.1uF caps across VREFP and VREFN pins as mentioned in the datasheet.

0 Nivethitha D over 1 year ago in reply to Praveen Aroul

Intellectual 370 points

Thanks for the comments praveen.

1) Also, wanted to know if we need external ADC or microcontroller inbuilt ADC with 12-bit ADC 5 Msps, up to 16-bit with hardware oversampling, 200 µA/Msps is enough FOR PACE DETECTION.??

Referred this https://www.ti.com/lit/ug/tidub75/tidub75.pdf?ts=1701344202238&ref_url=https%253A%252F%252Fwww.ti.com%252Ftool%252FTIPD197

2)What exactly is the use of these pins? In which cases these have to be connected?

Is the connection in the schematics above correct? any change to be done?

(RLDIN, RLDOUT, RLDINV)

3) What is the purpose of those RC filters near ECG Connector? why specially those values given in EVM as well?

4) Also please explain 10.2.1 ADS129xR Respiration Measurement Using Internal Modulation Circuitry in https://www.ti.com/lit/ds/symlink/ads1296r.pdf

5)Any other change to be done?

Thanks in advance. Quick reply would be appreciated.

0 Praveen Aroul over 1 year ago in reply to Nivethitha D

TI__Mastermind 49916 points

Hello Nivethitha,

Give me until next week to get back to you.

0 Nivethitha D over 1 year ago in reply to Praveen Aroul

Intellectual 370 points

Hi praveen,

Any updates for the above?

Please do reply. Is pace detection circuit good to go? Do you have any other comments in the working?

+1 Praveen Aroul over 1 year ago in reply to Nivethitha D

TI__Mastermind 49916 points

Hi Nivethitha,

1. Yes it should be ok if the micro's in-built ADC meets the performance spec. of ADS7042 and so long as you can take care of any digital noise from the MCU is getting coupled into the system.

2. The RLD amp is used as a feedback loop to set the bias voltage to the patient body. It effectively centers the electrode input voltage relative to the input common mode, thus providing maximum input dynamic range. It also improves CMRR performance rejecting noise and interference from external sources.

3. The RC filters in the signal path are primarily used for antialiasing purposes. It's not necessary to set the cutoff frequency exactly at the end of your bandwidth of interest. The goal should be to attenuate signals near the modulator sampling frequency for delta-sigma ADCs.

4. Refer to the application brief to understand the concept behind respiration modulation and demodulation.

https://www.ti.com/lit/an/sbaa181/sbaa181.pdf

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ADS1298R: ADS1298R Schematics Review