ADS1292RECG-FE: ADS1292RECG-FE measurement circuit on the resistance value

Kevin Peng

Part Number: ADS1292RECG-FE
Other Parts Discussed in Thread: ADS1292R

Hi Sir

ADS1292RECG-FE for ECG measurement circuit on the divider circuit resistance 10M 1% & 10M 1%. Can convert change to 1 M 1% value? Will there be any effect?

as follow figure below making , thanks

over 6 years ago

0 Brian Pisani over 6 years ago

TI__Mastermind 38745 points

Kevin,

Those resistors and the series capacitor directly in front of them form a high-pass filter. In the ac domain, the resistors are in parallel. Therefore, the cutoff frequency of that high pass filter is 1/(2*pi*5MOhm*2.2nF) = 14 Hz. If you use 1 MOhm instead the cutoff will be 144 Hz. Since the excitation signal you are measuring on that channel has a frequency of 32 kHz, having a bandwidth of 144 Hz will probably not affect it.

However, for some applications that need to pass regulatory certification, there is minimum input impedance required. Reducing the resistor value will lower the input impedance.

Regards,
Brian Pisani

0 Kevin Peng over 6 years ago in reply to Brian Pisani

Prodigy 240 points

Hi Brian

thank for your speed reply.

0 Kevin Peng over 6 years ago in reply to Brian Pisani

Prodigy 240 points

Hi Brian,
Then ask ,follow top figure whether the RC series value (Pin 31, 32) of the ADS1292R can be modify to R69,R70 = 100Kohm, C45,C47 = 1nF instead.
THANKS
Regards,
Kevin

0 Brian Pisani over 6 years ago in reply to Kevin Peng

TI__Mastermind 38745 points

Kevin,

Yes that should be fine as a cutoff frequency, but please take into account my comments regarding input impedance.

Brian

0 Kevin Peng over 6 years ago in reply to Brian Pisani

Prodigy 240 points

Hi Brian,
THANKS support
Regards,
Kevin

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ADS1292RECG-FE: ADS1292RECG-FE measurement circuit on the resistance value