customer design power banks for OEMs
the DCP setting auto as:
CTL1=0
CTL2=1
CTL3=1
ILIM_SEL=1
Mode = DCP auto (DCP load present)
its observed that when connecting to a Macbook pro13 with function keys (A1708) 2016 model
the TPS2546 will have the D+ and D- at 3.25V resulting bigger current drawn and triggers OCP
can we check with the development team, is this a special feature to support 3.25V at D+D-?
at what conditions it will have this mode?
Thanks
Hi Donovan,
is there further comments on the TPS2546 EVM overcurrent behavior?
we further tried using the TPS2549 EVM with the MAC PRO
the TPS2549 EVM doesn't have this problem, although the D+/D- still jumps to around 3.3V but the current output is around 1.6A
please help on checking the issue on TPS2546, and can you also let us know if customer would like to switch their deisgn from TPS254 to TPS2549
is there design changes that they need to make? ( anything they need to watch for? or just direct replacement?)
TPS2549 EVM Waveform
CH2 D-
Ch3 D+
CH1 VBUS
CH4 current
Hi John,
I just got back from my team member in Shenzhen who has a MacBook Pro they use to test with a TPS2546EVM. They see the same issue occurring with the D+ and D- voltages going to 3.2V. The TPS2546 seems to be entering 1.2V mode which is incorrect as Apple devices do not do 1.2V mode. This probably has to do with the MacBook Pro using USB Type-C Power Delivery which devices such as older Iphones and Ipads do not use (they use divider modes 1 and 2).
My team member also probed the D+ and D- lines when the MacBook Pro is plugged into it's standard power supply via Type-C and see the image below which could explain what is happening.
As you can see both D+ and D- get pulled up to about 3.2V. It looks like the MacBook Pro port is trying to do USB Type-C Power Delivery. The TPS2546 only does USB BC1.2 and divider modes which the Mac Book Pro does not seem to be recognizing and thus we are seeing a non-typical voltage on the D+ and D- lines.
It's interesting that the MacBook Pro draws less current when connected to a TPS2549. This may have to do with the TPS2549 having the newer Divider Mode 3 which puts 2.7V on both the D+ and D- lines. However, the voltage is still at 3.3V on the D+ and D- lines which is unexpected behavior. The main differences between the TPS2549 and TPS2546 is the divider modes (TPS2549 does Divider mode 3 only which takes care of all Apple devices), cable compensation (TPS2549 supports this, TPS2546 does not), and continuous current limit (3A for TPS2549, 2.7A for TPS2546).
What is the application for this design? This is the first time we have had a MacBook Pro connected to one of these EVMs. This family of devices TPS254* were designed for phones and tablets before laptops used USB Type-C PD to charge.
Regards,
Donovan
