Tip / Sign in to post questions, reply, level up, and achieve exciting badges. Know more

USB EZ-PD™ Type-C Forum Discussions

NiMc_4245981
Level 3
10 replies posted 10 questions asked 5 replies posted
Level 3

I'm working on a device based on CYPD3120-40LQXI.  The device can be either powered by the USB C cable or by an external barrel connector.  I'm unable to detect when the barrel connector is connected and I am ready to power up down-stream supplies.  I have VBUS_P connected (pin 40) but I can't figure out how to determine what is available.  I could use the pd_adc_sample function, but I don't know what value to use for port_pin, or if it would be valid.  Is there another way?

0 Likes
1 Solution
RajathB_01
Moderator
Moderator 250 replies posted 100 replies posted 50 replies posted
Moderator

Hi,

Pin 40 cannot connect to ADC.

There are no documentation that describe more register info than ccg3_regs.h

Can you see if you can use VSYS? VSYS_DET comparator can be used to detect changes on the VSYS supply.

Regards,

Rajath

View solution in original post

0 Likes
3 Replies
NiMc_4245981
Level 3
10 replies posted 10 questions asked 5 replies posted
Level 3

I found the ncell_status register and the PDSS_NCELL_STATUS_VBUS_P_STATUS mask, which I think might contain the information I want, but it is always 0.  Is there some documentation for these registers that goes into more detail than ccg3_regs.h?

0 Likes
RajathB_01
Moderator
Moderator 250 replies posted 100 replies posted 50 replies posted
Moderator

Hi,

Pin 40 cannot connect to ADC.

There are no documentation that describe more register info than ccg3_regs.h

Can you see if you can use VSYS? VSYS_DET comparator can be used to detect changes on the VSYS supply.

Regards,

Rajath

0 Likes
NiMc_4245981
Level 3
10 replies posted 10 questions asked 5 replies posted
Level 3

I'm detecting if VBUS_P is present by detecting if VSYS is present while the VBUS_C FETs are disabled.  This would indicate that VBUS_P is supplying my VSYS supply.

I also had to add a resistor to discharge the capacitor on VBUS.  Without that, I could quickly switch from external power to USB power without the CCG noticing (since the VBUS_P FETs are enabled.)  The resistor solved some other problems as well.