TUSB7340: TUSB7340 throughput

Viktorija Cecil

Part Number: TUSB7340

Team,

My customer has a question regarding the TUSB7340 PCIe to 4 port USB3/2 host controller IC:

Looking at the block diagram provided it appears that this IC is configured as a USB3/USB2 root hub with 4 ports rather than 4 independent USB3/2 controllers. The reason this is important is that the throughput limitations of a single controller with 4 ports severely restricts the possible data throughput for USB2 operation. Specifically I want to know is if I have 4 USB2 devices all trying to operate at high speed (480Mb/s), will the chip support this throughput, or will it throttle it down to 25% of that due to the 4:1 nature of the internal hub?

Thanks

Viktorija

over 8 years ago

0 Elias Villegas M. over 8 years ago

TI__Guru* 76130 points

Hello,
The USB 2 protocol grant full bandwidth to every downstream device (theoretically), this will change if the downstream devices are for example Isochronous, in that case the bandwidth will be distributed evenly on the four devices, in other words the available bandwidth is more related to the USB specification rather than this Device.
Regards

0 Chris Wagner over 8 years ago in reply to Elias Villegas M.

Prodigy 30 points

If I understand your response correctly, the TUSB7340 acts the same way that a 4 port USB2 hub does. Any individual port can be supported at full bandwidth, but if the downstream ports are all operating simultaneously, the total bandwidth of the 4 downstream ports is limited to 480Mb/s so the net bandwidth for each port is effectively reduced to ~120Mb/s.

0 Elias Villegas M. over 8 years ago in reply to Chris Wagner

TI__Guru* 76130 points

Correct.

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TUSB7340: TUSB7340 throughput