LDC1614-Q1: tolerance of DATAx value with given frefx tolerance

Shinji Tsuji

Part Number: LDC1614-Q1
Other Parts Discussed in Thread: LDC1614

Hi team,

Could you advise the tolerance of DATAx value captured by LDC1614-Q1 if I use external clock input for frefx with 50ppm tolerance?

Does the measured DATAx result also has 50ppm error?

regards,

over 5 years ago

0 Kristin Jones93 over 5 years ago

TI__Genius 17440 points

Hi Shinji,

Yes, the error in Fref will show up directly in the DATAx output. However, there may be additional sources of error that impact DATAx. For example, the thermal expansion of the PCB will slightly change the inductance value over temperature. EMI can also impact the sensor if it is within the pass-band of the LC tank sensor or if long traces or cables are used to connect the LC tank sensor to the LDC1614.

The best way to determine the error is to measure the noise floor over temperature without a target present. More details about LDC1614 resolution can be found in this application note.

Best Regards,

0 Shinji Tsuji over 5 years ago in reply to Kristin Jones93

TI__Genius 12978 points

Hi Kristin,

Thank you very much. I have one more question about the measurement error.

Is there any way to calculate how much measurement error is improved by increasing the conversion time?

I am trying to change Rcount to increase the conversion time from 0.596ms to 1.638ms.

RCOUNT：04d8
tc0 = (RCOUNTx16)/fref　 = (1240x16)/40MHz = 0.596(msec)
RCOUNT：1000
tc0 = (RCOUNTx16)/fref　 = (4096x16)/40MHz = 1.638(msec)

regards,

0 Kristin Jones93 over 5 years ago in reply to Shinji Tsuji

TI__Genius 17440 points

Hello Shinji,

My apologies for the delayed reply; I was on vacation all of last week.

There's no easy way to calculate exactly how much measurement error is improved by increasing the conversion time.

Best Regards,

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LDC1614-Q1: tolerance of DATAx value with given frefx tolerance