TPS65987D: Connecting to two USB ports

Nir Dvash1

Part Number: TPS65987D
Other Parts Discussed in Thread: TPS65987

Hi All,

In our product, we have 2 separate USB type C ports which can be used to charge the product's battery. Let us call one of

these ports Master and one Slave. The logic of the product requires that if the Master port is already connected it will disable

the Slave port. If only the Slave port is connected, it will be able to charge the battery.

My plan was to connect each of the VBUS lines from the two connectors to the two VBUS inputs of the TPS65987, short circuit the four PP_HV lines and configure the device to sink current from both channels. I will connect all other digital lines from the two connectors (CC1,CC2, etc) through a digital mux and feed it's outputs to the TPS65987 and other units in my system. The control over the digital mux selection will be based on the VBUS line of the master so when it is present, it's digital lines will be outputted by the mux and vice versa.

I hope my explanation is clear enough and I will gladly welcome any inputs/remarks/suggestions.

Thank you,

Nir.

over 5 years ago

0 Prajith Cheerakkoda over 5 years ago

TI__Expert 8940 points

Hello Nir,

VBUS1 and VBUS2 pins needs to be shorted on 87 if you are planning to use both of them. VBUS2 cannot act as VBUS independently.

Thanks
Prajith

0 Nir Dvash1 over 5 years ago in reply to Prajith Cheerakkoda

Intellectual 470 points

Hello Prajith,

So this means I will need a separate 87 for each of my USB ports?

Also, on the eval board schematics of the 87 it shows both VBUS inputs tied together but on data sheet of the 87 it states and shows VBUS2 (which is not used) connected to GND. Please advise what would be better assuming I will not be using VBUS2.

Thank you,

Nir.

0 Prajith Cheerakkoda over 5 years ago in reply to Nir Dvash1

TI__Expert 8940 points

Hi Nir,

You can use two 87 or dual port PD controller 88DDH.

VBUS1 is the actual VBUS of 87. VBUS2 is actually an internal power path pin (other end is PPHV2).

VBUS1 path can be used as Src and VBUS2 as sink in DRP applications, this is the typical use case.

Other use case; VBUS2 internal power path can be enabled in parallel w/ VBUS1 path to reduce the total resistance of internal path. You can find the details here - https://www.ti.com/tool/USB-C-PD-DUO-EVM.

Thanks
Prajith

0 Nir Dvash1 over 5 years ago in reply to Prajith Cheerakkoda

Intellectual 470 points

Hello Prajith,

I have followed your suggestion and changed my design to use a single TPS65988DJRSHR to handle our two USB type C ports.

I am including the new schematics and would be grateful if you can or someone from TI can verify my new design, especially the power path from the connectors and through the 88 (VBUS1, VBUS2, C1_CC1/2, C2_CC1/2, PP_HV1,PP_HV2)

One specific question that came to my mind: Assuming the schematics is correct, what will happen if the user connects a power supply to each of the two ports? will it short-circuit?

Thank you,

Nir.

TPS65988DJRSHR.pdf

0 Prajith Cheerakkoda over 5 years ago in reply to Nir Dvash1

TI__Expert 8940 points

Hi Nir,

Are these ports UFP only?

You had mentioned "The logic of the product requires that if the Master port is already connected it will disable the Slave port. If only the Slave port is connected, it will be able to charge the battery." So, only one port will be active at a time, correct? May I know if this requirement is taken care in the design?

Please reserve a pull up resistor on ADCIN2 pin.

Thanks
Prajith

0 Nir Dvash1 over 5 years ago in reply to Prajith Cheerakkoda

Intellectual 470 points

Hey Prajith,

Yes, both of these ports will be UFP only. As for the logic - yes, I wanted only one port to be active at a time but I did not implement it yet in the current design that you see. Is it possible to implement it with the current hardware (the 88?) or will I need more hardware to support this?

Thank you,

Nir.

0 Prajith Cheerakkoda over 5 years ago in reply to Nir Dvash1

TI__Expert 8940 points

Hello,

There are two ways to manage multiport sink policy.

1) Use Multiport Sink Policy in the GUI.

2) Use Plug Event (GPIO event) to trigger SRYR command.

Please find more on SRYR here- https://www.ti.com/lit/ug/slvubh2b/slvubh2b.pdf?ts=1601359849221&ref_url=https%253A%252F%252Fwww.ti.com%252Fproduct%252FTPS65987D

GPIO event - https://www.ti.com/lit/an/slva838/slva838.pdf?ts=1601360026746&ref_url=https%253A%252F%252Fwww.google.com%252F

Thanks
Prajith

0 Nir Dvash1 over 5 years ago in reply to Prajith Cheerakkoda

Intellectual 470 points

Thank you Prajith - I will look into these links.

Did you have a chance to go over my design in terms of hardware?

Nir.

0 Prajith Cheerakkoda over 5 years ago in reply to Nir Dvash1

TI__Expert 8940 points

Hi Nir,

It looks good to me. Two points 1. Add ESD protection on CC lines based on the system requirement. 2. Please reserve a pull up resistor on ADCIN2 pin.

Thanks
Prajith

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TPS65987D: Connecting to two USB ports