TPS65987D: AMSEL signal level question

Ricky Chan

Part Number: TPS65987D

Hi all：

Hi，I have a new design using the TPS65987D + HD3SS460 ,to achieve USB3.0 and DP display through Type-C interface。

There is a phenomenon, what could be the cause?
The premise is: AMSEL has External circuitry to pull-up 100k and pull-down 100k.
Here are the steps:
(1) do not connect the dock to Type-C interface, power on the motherboard, AMSEL = 0V.
(2) Connect the dock to the Type-C interface, ALSEL = 0V.
(3) Unplug the dock from the Type-C interface and test AMSEL = 1.6V.
It can be seen that (3) and (1) are the same physical / device connection status: do not connect the dock to Type-C interface,
But (3) AMSEL = 1.6V and (1) AMSEL = 0V are different.
Why is this happening?

over 5 years ago

0 Adam Mc Gaffin over 5 years ago

TI__Mastermind 30000 points

Hello,

You do not need external circuitry for the AMSEL GPIO event. You can reference the Host Interface document for more details (link below). The AMSEL GPIO event is a push-pull output event, so you do not need any external circuitry.

https://www.ti.com/lit/ug/slvubh2b/slvubh2b.pdf

0 Ricky Chan over 5 years ago in reply to Adam Mc Gaffin

Prodigy 60 points

Hello，

To achieve a mid-rail voltage（AMSEL = M）needs pull-up and pull-down in AMSEL？

Another question：

When will the PD controller recognize the DP input， and then set the corresponding voltage of AMSEL。Is there a timing diagram。

Best Regards.

0 Adam Mc Gaffin over 5 years ago in reply to Ricky Chan

TI__Mastermind 30000 points

Hello Ricky,

There is no mid-rail option for this GPIO event.

There is not a timing diagram. This can be measured using an EVM, programing the relevant GPIO with the AMSEL event, connecting a DP capable device, ad measuring the time from when voltage is presented on VBUS and this GPIO either goes high or low

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TPS65987D: AMSEL signal level question