STUSB1600 can't work as source

Gerald_W · ‎2024-10-04

Dear All,

Hello everyone, I used STUSB1600 as the type-c dual role type power management. When it works as sink type, it is good. But when it works as source type, it doesn't work. I found VBUS_EN_SRC always keep high. This is my design schematic, could you please provide some suggestions. Thank you so much!

Best wishes,

Gerald.

NBALL · ‎2024-10-08

Hello Gerald

As stusb1600 is in DRP configuration, without any cable connected, I do expect to see CC toggling between ~3V and 0v

By default, Rp is setup to advise 3A so when Sink is connected, I expect to see 1 CC pin at ~1.6V.

If CC are zero when connected to sink, it means that stusb1600 is in ErrorRecovery state (it has disabled its resistors): most probably, the device detects wrong voltage on power paths.
VDD pin should be connected between U8 and U9 from your schematic: see fig 10 of our datasheet.
Best regards
Nathalie

Gerald_W · ‎2024-10-08

Hi Nathalie,

Thanks for the clarification. I just found out why the STUSB1600 cannot be used as a source. On the PCB I was testing, I connected VSYS to GND. When I reworked the PCB and tried to connect VSYS to 5V, as shown in the figure above, vbus_en_src is normally pulled low, and the STUSB1600 could be used as a source to output to external devices.

The description of VSYS in the manual is very vague. Could you please help clarify the function of VSYS? Under what circumstances should VSYS be connected to GND?

Thanks,

Gerald

Gerald_W · ‎2024-10-09

Hi Nathalie,

Thanks again for your advice. But I think the VDD in the datasheet is connected to the branch that controls the Battery Charger, which is the same as my schematic.

And this is the CC1 waveform:

This is CC2 waveform:

Thanks,

Gerald