ECMF02-4CMX8 - pin connection for USB type C application

[gabrielefilosofi]

Hi,

I want to use ECMF02-4CMX8 as ESD protection and filtering means for a isolated USB 2.0 downstream port design.
The chosen connector is a Type C receptacle.
My question pertains to pin function of ECMF02-4CMX8.
The type C connector exposes two configuration pins, CC1 and CC2.
Can I connect CC1 to pin 4 and CC2 to pin 1 ?
From the datasheet I know the pin 1 is reserved to VBUS and pin 4 is reserved to ID, however I prefer to assign this 1 pin to CC2, and route VBUS to a separate over-voltage protection chip (MAX14699EWC+).
Is my choice correct and safe ?
I attach the proposed schematic for the complete interface.

Thank you for any help
Gabriele

[MROUV.1]

Hi Gabriele,

 

Good idea !

CC1 and CC2 can be protected with ID and VBUS pin of ECMF02-4CMX8.

 

Embedded ESD protection for ID and VBUS are not identical.

VBUS is more capacitive (19pF) and much more robust 2.5A 8/20µs.

In any case, both protections do not impact normal behavior of Type-C.

 

It is key to protect CC1 and CC2 if these lines are used to sense the adapter current capability (0.5A or 1.5A or 3.0A) according to the CC1 or CC2 line voltage.

If not used, then ECMF2-40A100N6 (QFN-6L) can be used. R20 and R21 do not require ESD protection.

 

Last comment, to protect the MAX14699 against surges, I recommend to place ESDA25P35-1U1M between VBUS and GND.

 

Best regards,
Mathieu

[gabrielefilosofi]

 

Hi Mathieu,

thank you so much.
The equipment is internally supplied from separate external adapter, not from USB.
It is assumed to be connected via USB to a standard PC for communication.
Are you sure I don't need ESD protection over CC1/2 ?
What if they attach a USB C power adapter with Power Delivery capability ?

Anyway, I've attached the updated schematics.
Do you think it is better ?

[MROUV.1]

Hi Gabriele,

 

Discrete ESD protections are not needed on CC1 and CC2 because these lines are only connected only to 5.1k pull-down resistors (no IC to be protected).

 

When any adapter is plugged. First, a standard type-C attach process is done (SINK to SOURCE)

After, USB Power Delivery adapter will try to communicate without success.

And the state will remain unchanged until un-attach detection.

 

The schematic is much better.

 

Best regards,

Mathieu

[gabrielefilosofi]

Mathieu,

this makes perfect sense.

Thank you,
Best regards

Gabriele