Differences between W7100 and W7100A

W7100A is the upgraded version of W7100. The main differences are as follows:

If you are using W7100 user software ported to W7100A, you must pay attention to the following points:

1. If there is no additional pull-up/down circuit for GPIO, the W7100A GPIO port can only be used after setting the pull-up/down register. User who need to use GPIO port must set pull-up/down of GPIO when initializing W7100A in order to use normal  0 ~ 3.3V  input/output voltage.
2. Since the PHY mode setting pins are deleted in the W7100A QFN64pin package. User must set operation mode of W7100A using PHTCONF SFR (Special Function Register). Set the MODE_EN bit and the MODE [2:0] bit of register PHYCONF SFR. Then set the PHY_RSTn bit  of PHYCONF SFR to reset W7100A. For more specific information about the operation mode value depending on MODE[2:0] bit, please refer to the PM pin value of W7100A DataSheet, “Pin Description” section.

Source: Differences between W7100A and W7100_v1.1