TPL0501-100: Ratio (RWL/RHW) accuracy

Troy MacDonald

Part Number: TPL0501-100

Hello,

The absolute resistance tolerance is +/-20%. In the data sheet above table 2, there is a line that says "The absolute values of resistance can vary significantly but the Ratio (RWL/RHW) is extremely accurate."

How accurate is the ratio (RWL/RHW)?

I interpret that as the voltage divider mode (?%) is significantly more accurate than rheostat mode (20%). I am thinking of connecting the part in such a way as to use the ratio (RWL/RHW) to set the gain of an op amp instead of relying on the absolute resistance values for a more accurate op amp gain.

Thank you

over 4 years ago

0 Akhilesh K over 4 years ago

TI__Mastermind 18546 points

Hi,

For this part absolute variation can be +/-20% as you said and total temperature coefficient is 35ppm/C.

In the ratiometric mode such as in voltage divider case, temperature coefficient is even tighter at 4ppm/C. You can use it to set the gain of an op amp in divider mode and get higher accuracy.

Are you looking for percentage accuracy mismatch error in divider mode? if that's the case please have a look at DNL specification which says +/-0.5LSB.

To interpret this in resistance percentage, do the following math

In terms of resistance = 0.5 * 100000 (this is the total resistance) / 256 (no of taps) = 195.312 ohms

Percentage = (195.312 / 100 K ) * 100 = +/- 0.195%

Regards,

0 Troy MacDonald over 4 years ago in reply to Akhilesh K

Prodigy 60 points

Thank you for your response.

Say I set it up to divide 5V to 2.5V by setting the step to 128. Is the tolerance I can expect on the 2.5V 20% and 4ppm/C, or is it 0.5LSB and 4ppm/C, or is it something in between?

Thank you

0 Akhilesh K over 4 years ago in reply to Troy MacDonald

TI__Mastermind 18546 points

Hi,

Matching will be +/-0.195% and across temperature will be 4ppm/C

Regards,

0 Troy MacDonald over 4 years ago in reply to Akhilesh K

Prodigy 60 points

Thank you for your help

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TPL0501-100: Ratio (RWL/RHW) accuracy