Question 1 :
TPS2546 setting :
- Enable pin control by host.
- Current limit, CTL1,2,3,ILIM_SEL are be connected to high. It setting to CDP mode.
Issue : TPS2546 can’t identify USB device at CDP mode.
With TPS2546 : HOST DN,DP <>TPS2546<> USB JACK : It could charging, but can’t identify USB device at CDP mode. (It can’t identify which USB device be connected. )
Without TPS2546 : HOST DN,DP <-> USB JACK : It could identify USB device.
Note:
1. CDP : TPS2546 can’t identify USB device if using CDP default mode. (It seems can’t communication at CDP mode. it can’t enumeration.)
2. SDP : SDP mode can identify most of USB devices, however can’t identify some of special vendor USB device.
3. It need to operating at CDP mode when chargeable USB device be connected. TPS2546 need to identify chargeable USB device and charging at CDP mode.
Question :
Q1_1 : What’s the reason about can’t communication at CDP mode ? Is there have way to identify USB device at CDP mode ?
Q1_2: Is it possible to output USB device type information to Host from TPS2546 ?
Question 2 :
Customer plan to use STATUS to check charging, no device attached and fully charged status.
TPS2546 setting charging current smaller than 45mA for 15s and setting limit to 55mA.
Q2 : What’s the background for 45mA and 55mA current value ?
Q2_1 : Dose 45mA is a normal USB chargeable device termination current level ? Why TI select termination current is 45mA ?
Q2_2 : Why current limit setting 55mA ? Why current level is not 60mA or 50mA ? Is there have any special reason ?
