On Page 13 of TIDU533, equation 24 shown below shows how to calculate R11. When I try to use the given example I get nothing shown in the photo.
R10 = 2490 ohms
Vmax = 15 V
Vmin = 5 V
Rpotmax = 7500 ohms
Rpotmin = 0 ohms
Vref = 0.8 V(given on page 12)
Solving for R11, i get -8.874 ohms, and obviously I'll also get the wrong answer for R7 using that. Did I miss something simple here and just bad at math or is the equation wrong?
Hi Dan,
Please refer to this e2e post: https://e2e.ti.com/support/data-converters-group/data-converters/f/data-converters-forum/995422/tpl0401a-10-the-calculation-of-one-parallel-resistor-rpar-r11-and-one-series-resistor-rser-r10
I re-derived the equation you are referring to. The team that wrote this TI Design said my equation checks out, but it still does not match the the values for R11 shown in the figure. The team doesn't have their original calculations as to how they calculated the R11 in the figure so we can't verify where those numbers came from.
Also, use figure 94 (full schematic) when replicating this design:
Figure 9 looks like it has R10 in series with R7. R10 should be connected at the connection or R7 and R11.
Let me know if you have any more questions.
Best,
Katlynne Jones
