TMCS1126-Q1: CMRR of hall sensor

Janus Meinert

Part Number: TMCS1126-Q1

Tool/software:

Hello dear TI

In the datasheet of the TMCS1126-Q1, I can see that the input referred Common Mode Rejection Ratio is specified to 5muA/V.
How do i convert this to dB instead?

4 months ago

0 Holly R 4 months ago

TI__Expert 6225 points

Hi Janust,

You first need to convert this to output referred CMRR such that the ratio is V/V.

For example if using the TMCS1126x7x with sensitivity = 30mV/A.

5uA*30mV/A = 0.15uV

CMRR = 0.15uV/V

CMRR dB = 20*log(0.15uV/V) = -136dB

Best,

Holly

0 Janus Meinert 4 months ago in reply to Holly R

Prodigy 30 points

Thanks for the quick reply Holly

I guess it is the same procedure if I want to know the PSRR in dB?

0 Janus Meinert 4 months ago in reply to Holly R

Prodigy 30 points

Thanks for the quick reply Holly

I guess it is the same procedure if I want to know the PSRR in dB?

0 Holly R 4 months ago in reply to Janus Meinert

TI__Expert 6225 points

Hi Janus,

Yes, as long as you convert it to a ratio of like values (ex. V/V) then you can use the standard formula to convert that ratio to dB.

https://www.allaboutcircuits.com/tools/decibel-calculator/

Best,

Holly

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TMCS1126-Q1: CMRR of hall sensor