FDC1004: Measured value error when changing the IC of FDC1004

Masayuki Seike

Part Number: FDC1004

Please tell me the degree of variation in the measured values when changing the IC in FDC1004.
It is easy to understand if the measurement target is the degree of variation in the measured values when the ceramic capacitor is 0.5pF.
Thank you.

over 4 years ago

0 John Miller - Sensing over 4 years ago

TI__Mastermind 40295 points

Masayuki,

Thank you for your inquiry and your interest in TI products.

Just so I can be sure I understand your question:
Are you looking for the tolerance of the capacitance measured by the FDC1004 when you simply change the IC and the PCB & components remain the same between the measurements?

Regards,
John

0 Masayuki Seike over 4 years ago in reply to John Miller - Sensing

Prodigy 20 points

Hi, John.

Your understanding is probably correct.

PCB:not change
components(measurement target?):not change
FDC1004:change

I want to know how different the measured values are at this time.

0 Nicole Khoury over 4 years ago in reply to Masayuki Seike

TI__Genius 10080 points

Hello Masayuki,

The absolute error after offset calibration has a typical value of ±6 fF. This specification can be seen in section 7.5 of the datasheet.

Best regards,

Nicole

0 Masayuki Seike over 4 years ago in reply to Nicole Khoury

Prodigy 20 points

Hi, Nicole.

How many Gain Calibration is at 6fF?

What happens if I don't do offset calibration? Is it indefinite?

+1 Nicole Khoury over 4 years ago in reply to Masayuki Seike

TI__Genius 10080 points

Hi Masayuki,

The parasitic capacitances of the FDC1004 are calibrated out at production. These parasitic capacitances can come from factors such as the initial capacitance of the sensor, or parasitic capacitances of the board traces and sensor connections. The gain is factory calibrated up to ±15pF for each part.

If there are other sources of offset, it may be necessary to further calibrate in the application. The maximum offset capacitance is 100pF. For more information, sections 8.3.2 - 8.3.4 of the datasheet offer further details.

Best regards,

Nicole

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FDC1004: Measured value error when changing the IC of FDC1004