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TPS1200-Q1: TPS12000-Q1 RISCP Calculation Formula Discrepancy (Datasheet vs. TI Excel Sheet)

Vinod Justin
Prodigy 105 points
Part Number: TPS1200-Q1
Other Parts Discussed in Thread: TPS4800-Q1

Tool/software:

Hi TI Team,

I'm currently working with the TPS12000QDGXRQ1 device and came across a discrepancy in the calculation of the RISCP resistor.

According to the datasheet, the formula for RISCP is:

RISCP = (ISC * RSNS - 19mV) / 2µA

However, in the TI-provided Excel calculator, the formula is:

RISCP = (ISC * RSNS - 10mV) / 2µA

This is a significant variation and could lead to different values for RISCP in our design.

To further add to the confusion, I reviewed the schematics of the TPS4800-Q1 EVM, and it appears that the Excel sheet formula (with 10mV offset) has been used there — not the 19mV stated in the datasheet.

Could you please help clarify the following:

1. Which formula is correct — the one in the datasheet or the one in the Excel sheet?

2. If 10mV is the correct value, is the datasheet outdated or in error?

3. Is there any silicon or application condition that warrants the difference in offset (10mV vs. 19mV)?

Thanks and Regards 

Vinod J 

Mistral Solutions.

  • 0
    TI__Expert 8250 points

    Hi Vinod, 

    The "-19 mV" from the datasheet is the correct equation.

    The "-10mV in the excel is an error. I will update the online calculator by tomorrow. To clarify I see the mistake in cells D23 and D31. Are you seeing it elsewhere? 

    The original RISCP equation used - 10 mV. And update was made at the time of RTM and the equation in the datasheet reflects this. 

    Thank you, 

    Sarah