Part Number:CC2564
We are using the CC2564B chipset on a Panasonic PAN1326B module connected for 3-wire communication (H5 protocol). In our design, we initially left the CC2564B CTS line floating as the datasheet seems to indicate that pin has an internal pull-up resistor (see page 13 of the datasheet). However, we found some of our devices were drawing very high current - up to 220uA when the theoretical maximum is less than 135uA. Attaching an external 10k pull-down resistor to CTS resulted in the high current devices drawing <85uA. This seems to indicate the CTS pin is actually floating on those devices an not internally pulled-up.
What are the connection requirements for the CTS pin on the CC2564B chip set and is there a pull-up resistor normally applied to the pin internally. If there is no internal pull-up, what is the meaning of the PU marking in the data sheet?