7.7 Internal Pull-up Resistors

The ATWILC3000A provides programmable pull-up resistors on various pins. The purpose of these resistors is to keep any unused input pins from floating, which can cause excess current to flow through the input buffer from the VDDIO supply. Any unused pin on the device should leave these pull-up resistors enabled in order to avoid the pin floating.

The default state at power-up should be enabled for the pull-up resistor. However, any pin which is used should have the pull-up resistor disabled. The reason is that if any pins are driven to a low level while the device is in the low-power Sleep state, current will flow from the VDDIO supply through the pull-up resistors, increasing the current consumption of the module.

Since the value of the pull-up resistor is approximately 100 kΩ, the current through any pull-up resistor that is being driven low will be VDDIO/100k. For VDDIO = 3.3V, the current would be approximately 33 μA. Pins which are used and have had the programmable pull-up resistor disabled should always be actively driven to either a high or low level and not be allowed to float.