Does the BQ24195 have USB 2.0 communication support in SDP/CDP like the TPS2543?
I looked around to see how the BQ24195 handles CDP/DCP in the datasheet, and I only found details about how the BQ24195 detects the DCP/CDP charging characteristics on p. 19 of the datasheet (according to USB Battery Charger Spec 1.2):
It seems that CDP/DCP detection is only for setting the appropriate input current limit. I did not find information about data communication (USB 2.0 Communication) during charging. However, I saw this in an earlier post by Charles Mauney below:
The D+/D- lines are used by the charger IC in the first 100ms of applied 5V power to determine if the D+/D- lines are shorted or biased as a high power port, and if so sets the input source as an adapter, otherwise it is treated as a USB source. The charger IC does not enumerate with the host.
The lines can be used in parallel for our IC and a USB transceiver in the device, for lower communication speeds, but may be an issue at the high speed communication. As you probably know, at high speeds unless the impedance of the lines is matched, with good layout techniques, one will get reflections that will be an issue. I am not an expert in this field, but do know that the communication lines are disconnected in the IC after the detection test is finished and possibly using some series resistance will help terminate the line through the capacitance of the disconnect FETs. I can't be much more help, but would like to know what your application is and how the process develops.
Since each customer’s board is different, TI has left this testing to the developer.
Most applications use a power path charger that powers the device's transceiver on application of the 5V source so the IC with D+/D- is not needed. For very low end designs, with no USB communication, that want to use the USB port as just a power source, this part works well.
Thoughts? How does the BQ24195 handle the data transmission part of CDP?
Thanks for your time and help!
Michael
