TS3USB221: TS3USB221 issue

GARETH OU

Guru 11905 points

Part Number: TS3USB221

The TS3USB221RSER schematic is shown in the diagram below. It is used to switch between USB 2.0 D+/D- and UART debug TX/RX outputs to the USB Type-A connector.

The UART (UART1_TX_3V/UART1_RX_3V) is connected to the CPU i.MX6 via a 3.3V/1.8V level shift IC. The USB 2.0 (USB_HUB_DP2/USB_HUB_DM2) is connected to the USB HUB as shown in the diagram below.

The HUB's power source is connected to the CPU i.MX6.

Phenomenon Description:

1. When powered off, if a USB flash drive is plugged into the Type-A connector and the device is powered on, the TS3USB221RSER has a certain probability (20%~50%) of causing the USB HUB to fail.

2. The same test with a keyboard/mouse plugged in fails.

3. Removing R434 (UART1_TX_3V defaults to 3.3V, suspected to be a source of interference) and 1D+... After grounding, the circuit tested normal 1800 times.

What are the possible causes and suggested solutions?

usb hub.jpg

1 month ago

0 Nir Gilgur 1 month ago

TI__Mastermind 23505 points

Hello Gareth,

To make sure I understand, you have the TS3USB221 powered off while you plug in a USB flash drive and then turn it on. In other words the TS3USB221 is powered off while having USB signals present on its I/Os, Is that correct?

Also, what do you mean by failure? Is the mux not passing the signals?

Thanks,

Nir

0 TT_Chin 1 month ago in reply to Nir Gilgur

Expert 2065 points

Hi Gareth,

For this case, if we remove R434 and R435 to disconnect 1D+(Pin1) and 1D-(Pin2) of TS3USB221, any concerns for the two floating Pins?

Sincerely,

Chin

0 Nir Gilgur 1 month ago in reply to TT_Chin

TI__Mastermind 23505 points

Hello,

Today and tomorrow are TI U.S. Holidays.
Responses will be provided on Friday.

Thanks,

Nir

0 Nir Gilgur 1 month ago in reply to TT_Chin

TI__Mastermind 23505 points

Hello,

No major concern if these pins are floating.
Might see some very small additional noise.

Thanks,

Nir

0 TT_Chin 1 month ago in reply to Nir Gilgur

Expert 2065 points

Hi Nir,

Roger that,thanks!

Sincerely,

Shichin

0 TT_Chin 1 month ago in reply to Nir Gilgur

Expert 2065 points

Hello Nir,

I suppose that there is no power/signals sequence needed between VCC, nOE and all input signals; does it make sense?”

Sincerely,

Chin

0 Nir Gilgur 1 month ago in reply to TT_Chin

TI__Mastermind 23505 points

Hello Chin,

Yes you are correct, there is no need for a specific power on sequence.
nOE and the I/Os are not dependent on the VCC voltage level.

Thanks,

Nir

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TS3USB221: TS3USB221 issue