Original question:
Hi team,
My customer plan to use DP83822I and they found the Strap Resistor Ratios with 1% tolerance are recommended in the datasheet.Like below pic.
They feedback the Resistor value is hard to purchase, like 1.96,2.49, 5.79 with 1% tolerance. So they want to know if Resistance accuracy must be so high?
Thanks!
Hello Eggsy,
The 1% tolerance recommendation is to ensure better control on the voltage present on the strap pins of the PHY during power-up/reset. In table 10 of the datasheet, the voltage range for each strap mode is listed. Customer can select different resistor value as long the equivalent voltage fits within the range of acceptable voltage for that strap mode.
For e.g., RX_D0 has a internal pull down resistor of 9kohm and is in default mode 1. If customer wants to strap it to mode 2, they can select different value of Rh and Rl resistors such that the equivalent voltage due to the resistors (internal 9kohm, Rh, Rl) is between 0.148xVDDIO and 0.181xVDDIO.
-Regards,
Aniruddha
