Hi Team,
Our customer use TPS25947xx_Design_Calculator.xlsm.
I understand that Tolerance of UV_final_falling(F51 cell) is constant cell.
Therefore, even if you change the accuracy of the input voltage divider resistors, this value does not change.
I have no idea what this value means.
Could you please let us know the meaning of 6.5% of F51 cell?
Regards,
Hide
Hi Hide,
Thanks for reaching out. Yes we are assuming 1% tolerance of resistors in resistor divider. Final UVLO threshold will vary due to variation in internal comparator UVLO and resistors value.
F51 is root mean square of all errors
F51 is sqrt((tolerance of comparator threshold)^2+(tolerance of R1)^2+(tolerance of R2)^2+(tolerance of R3)^2)
F51 is not constant. Since calculator is locked you cannot change that value, currently it is based on 1% tolerance of resistors. You can calculate for any resistor tolerance using above formula.
Regards
Kunal Goel
Hi Kunal-san,
I have one more question.
Our customer used your formula to calculate Tolerance of F51.
Then, tolerance of R1,R2,R2 are 1%.
At the result, not 6.5% of F51.
Could you please let us know if there is any setting error?
[Method of calculation]
2.15≒sqrt((tolerance of comparator threshold)^2+(tolerance of R1)^2+(tolerance of R2)^2+(tolerance of R3)^2)
= sqrt((1.28)^2+(1)^2+(1)^2+(1)^2)
*Tolerance of comparator threshold is 1.28 depended on datasheet.
Regards,
Hide
