TPS25858-Q1: Value of Rcc1 and Rcc2

Jeison Arcos

Part Number: TPS25858-Q1

Tool/software:

Hello,

Based on the schematics provided in the related question, my device is not detecting when I connect a device to the USB-C port. the Resistor (R8-R11) seem to be incorrect. I tested multiple values and nothing was working. So instead I changed to connection, as shown the R were connected to ground with a 1K resistor, but now i connected to PA_bus and PB_Bus with a 50.6K resistor. My device now detects a plugged device and provides 5V. Could someone verify this is the correct function my design is supposed to work as a source not as sink. This is the reason I change the R value, the specifications does not clearly delineates the changes required and the EVM only shows Ra and Rd no Rp.

Thank you,

Jeison

20 days ago

0 Jeison Arcos 20 days ago

Prodigy 45 points

small update, while monitoring the voltage on the Vbus (with Rcc1 and Rcc2 pullup to Vbus), both ports show 2.3v with no load, but when a load is connected the voltage fluctuates drastically from 0.2v to 5V, no I is presented to the load, and it continues in a connect-disconnect cycle.

0 Eric Hartigan 20 days ago

TI__Expert 5665 points

Hi Jeison,

There shouldn't be any resistor from CC to GND on your board. When a device connects to the port, it will have a 5.1k resistor to GND that get's exposed to CC1 or CC2 (depending which way the Type-C cable is connected). When TPS25858-Q1 detects this resistance, it will enable VBUS.

Page 4 of this article explains the detection/orientation mechanism: https://www.ti.com/lit/wp/slyy109b/slyy109b.pdf

Regards,
Eric

0 Jeison Arcos 20 days ago in reply to Eric Hartigan

Prodigy 45 points

Hello Eric,

Thank you so much for your reply, I have made the adjustment and removed all the Rs on CC lines, and when a tester is plug both ports show 5.1V however when i put a load on the ports, the voltage fluctuates between 5v to .2v on PA_bus and PB_bus. SENSE is at 5V constant. EN is at 2.7V any advise is greatly appreciate it. I have made 1 change and replaced C5 to 1uF. my VIN = 13.5v

Jeison

0 Eric Hartigan 16 days ago in reply to Jeison Arcos

TI__Expert 5665 points

Hi Jeison,

I expect the device is entering current limit when you apply the load. Is R7 installed? And what is your load condition?

Thanks,
Eric

0 Jeison Arcos 15 days ago in reply to Eric Hartigan

Prodigy 45 points

Hello Eric,

Thank you for your reply, yes R7 is installed and for my test load i just use a regular 3.7v battery that i keep at about 30% charge, pulling 5v @ 2A.

Thank you

0 Eric Hartigan 15 days ago in reply to Jeison Arcos

TI__Expert 5665 points

Jeison,

Can you share a scopeshot of the bus voltage and current, along with VIN?

With R7 installed, you shouldn't be hitting current limit (3.55 A). But based on your description of the SENSE pin and the BUS pins, this sounds like what's happening.

0 Jeison Arcos 11 days ago in reply to Eric Hartigan

Prodigy 45 points

Hello Eric,

Thank you for your reply, I will get you a scopeshot on monday,

Thank you

0 Eric Hartigan 10 days ago in reply to Jeison Arcos

TI__Expert 5665 points

Hi Jeison,

Thanks. Hopefully it will clear things up..

Regards,
Eric

0 Jeison Arcos 8 days ago in reply to Eric Hartigan

Prodigy 45 points

Hello Eric,

This is my VIN checked several caps to verify voltage at in

This next 2 are SENSE at different scale

This next 3 are Vbus with the load

If any other information is required please let me know.

Thank you,

Jeison

0 Eric Hartigan 8 days ago in reply to Jeison Arcos

TI__Expert 5665 points

Hi Jeison,

The VBUS high/low timing doesn't align with any device characteristics. One thing I found in your schematic is pin 6 (AGND) appears to be floating. Can you ensure this is connected to GND?

I'm also curious if the CC1 or CC2 voltage is steady with regards to VBUS. Can you capture VBUS, IBUS, CC1, and CC2 on a single scopeshot?

Thanks,
Eric

0 Jeison Arcos 8 days ago in reply to Eric Hartigan

Prodigy 45 points

Hello Eric,

About pin 6 I did catch that before I my test board got printed. I have checked the actual boards and they are grounded.

Regarding the scopeshot I will give it a shot tomorrow, I do have 4 probe inputs i will need to check if i have 4 probes. about IBUS i was checking i have no direct way to get IBUS shot but will get the others.

Thank you

Jeison

0 Eric Hartigan 7 days ago in reply to Jeison Arcos

TI__Expert 5665 points

Hi Jeison,

Were you able to get a scope shot?

Thanks,
Eric

0 Jeison Arcos 6 days ago in reply to Eric Hartigan

Prodigy 45 points

Hello Eric,

Apologies, I was not able to get you the shots, I will get them on Monday.

Thank you,

Jeison

0 Eric Hartigan 6 days ago in reply to Jeison Arcos

TI__Expert 5665 points

Sounds good.

Regards,
Eric

0 Jeison Arcos 3 days ago in reply to Eric Hartigan

Prodigy 45 points

Hello Eric,

Sorry for such a late reply, here is are scopeshots

this are CC1 and CC2 alone

and this is with Vbus

And this is just a USB tester with no load

Thank you.

0 Eric Hartigan 3 days ago in reply to Jeison Arcos

TI__Expert 5665 points

Hi Jeison,

From what I can see, CC1, CC2 are always active and pulling up, looking for a connection. When these signals rise, it indicates Rd was removed from one of these pins (channel 2, t~=800ms). This tells TPS25858-Q1 the device detached from the port, so VBUS disables. Channel 2 sees a falling edge at t~=1.4s, indicating the device attached to the port, so VBUS is re-enabled.

From the port controller's perspective, it is always prepared to provide output. But it sees Rd (the device on the other end of the cable) constantly attaching/detaching. I am not sure why this would occur. Do you have another load you can check with? Also, can you zoom in on the rising edge of CH2 to see if the dip to 0V at t~=800ms is real? Please ensure the scope lead has a local ground on it.

Here are some figures from the datasheet where I've correlated your waveform to the Rd attach/detach waveforms.

Regards,
Eric

0 Jeison Arcos 2 days ago in reply to Eric Hartigan

Prodigy 45 points

Hello Eric,

Again thank you for your reply, I have tested on an actual cell phone using the app ampere to check charge. the phone shows the same characteristics as here it initiates connection and then it drops it and the cycle repeats. I will try to see if i can get the scopeshot using the phone as a load.

Thank you,

Jeison