Regarding USB De-multiplexer + USB Hub

Appala Raju Gottipilli

Other Parts Discussed in Thread: TS3USB221A, TUSB2046B

Hi,

I need design like, USB 2:1 De-multiplexer (which has two inputs and one output) output should be connected to 1:4 USB Hub.

I mean, need to switch USB Hub between two USB Hosts based on some enable signal.

I selected ts3usb221a as a De-multiplexer and tusb2046b as a USB Hub. Can I use these two ICs for my requirement.

If not, Could you please suggest me best suitable ICs for my requirement.

And also, please provide me the schematic for this design.

I have a one query, while switching from one host to other, do we need to give reset to USB Hub chip?

What is the purpose of RESET input signal of USB Hub(tusb2046b).

Thanks,

Raju.

over 13 years ago

0 DHarmon over 13 years ago

TI__Genius 16460 points

Raju,

There is nothing wrong with your idea. The question becomes what SUB speed peripherals do you need to suport. the TUSb2046B supports USB full-speed (12 Mb/s) as its maximum data transfer rate. If you need USb high-speed (480 Mb/s) support, TI does not have such a hub.

We do not have a schematic showing these two devices working togther - attached is a reference design for the TUSB2046B as a self-powered hub.

When the switch is "thrown" to change which host PC is talking to the hub, it will go through a full re-enumeration on the new host system. Reset is only need to be changed if power-cycling.

2046-PlainSelfPower.pdf

0 Appala Raju Gottipilli over 13 years ago in reply to DHarmon

Intellectual 280 points

Hi DHarmon,

Thanks for the clarification. 12 Mb/s is ok for me.

Could you please provide me the schematic diagram for "TS3USB221A" USB switch also.

Thanks,

Raju.

0 DHarmon over 13 years ago in reply to Appala Raju Gottipilli

TI__Genius 16460 points

The TS3USB221A is supported by a different business unit and I have asked them to respond - you could also post your request in the Signal Switch forum which is closely monitored by that support team.

0 Eric Nachtigal over 13 years ago in reply to Appala Raju Gottipilli

TI__Prodigy 450 points

2350.scdu001a[1].pdf

Raju,

Attached is the EVM guide for the TS3USB221A. On page 7 there is the schematic for the EVM, the documentation also displays the EVM layout layers. Below is a link to the TS3USB221A EVM page if you would like to order a board to test.

http://www.ti.com/tool/ts3usb221aevm#descriptionArea

Regards,

Eric N.

0 Appala Raju Gottipilli over 13 years ago in reply to Eric Nachtigal

Intellectual 280 points

Hi Eric N,

Thanks for the reply. I have prepared schematic for this, based on your inputs.

Attached document here.

Could you please review it and provide me your suggestions or modifications.

Thanks,

Raju.

USB_SWITCH.pdf

0 Eric Nachtigal over 13 years ago in reply to Appala Raju Gottipilli

TI__Prodigy 450 points

Raju,

The only suggestions I would recommend is there is no need for the 10k resistor on Vcc unless you have a specific reason for using it. You many also wish to consider a 1uF decoupling cap on Vcc.

This is assuming the 3.3V LDO power supply is implemented correctly, if you are unsure of this I recommend using the part/design in the EVM guide.

Regards,

Eric N.

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Regarding USB De-multiplexer + USB Hub