TUSB4041I-Q1: Power supply

Antonio Bardi

Part Number: TUSB4041I-Q1

On a board prototype I included a TUSB4041I-Q1 to provide multiple USB ports from a single USB port coming from an NXP i.MX8 CPU.
The problem is that the device is not seen by the CPU (running Linux)
Checking device supplies, I measured around 1.8V on the 1.1V supply pins.

1. Bad supply? No, opening the supply connections I found that the DC/DC is working correctly (1.1V and 3.3V).
2. Device malfunction? Maybe. Supplying 3.3V pins only, I found the undesired 1.8V on the 1.1V device supply pins (unconnected to its 1.1V DC DC output)
3. Device Ground pad not correctly soldered? Maybe.

The question is:
is the ground pad the only device connection to Ground?
Is there a simple electrical test to check that the Ground pad is correctly soldered?

Thanks

-Antonio-

over 5 years ago

0 Brian Zhou over 5 years ago

TI__Guru*** 145460 points

yes, only has pad ground for this device. not sure there is a test to check pad connection. but what is the timing for 3.3v and 1.1v?

0 Antonio Bardi over 5 years ago in reply to Brian Zhou

Prodigy 50 points

Thanks Brian.
About the timing, from TI datasheet:

"The VDD33 (3.3V) and VDD (1.1V) have no power-on relationship unless GRSTz is only connected to a capacitor to GND. Then VDD must be stable minimum of 10 μs before the VDD33."

But this is not my case (I have the GRSTz reset line pulled up).

-Antonio-

0 Brian Zhou over 5 years ago in reply to Antonio Bardi

TI__Guru*** 145460 points

since GRSTz has internal PU, the external Cap sill keep it low for a while wwhen power up. Can you take a waveform?

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TUSB4041I-Q1: Power supply