Skip to main content
Knowledgebase
Home
Renesas Singapore - Knowledgebase

What is the difference between Single- TT and Multi-TT?

Latest Updated:06/01/2006

Question:

For the USB hub controller, what is Transaction Translator? What is the difference between Single- TT and Multi-TT?

Answer:

The Transaction Translator (TT) is a temporally buffer to translate data transaction of target LS/FS device connected to downstream ports of hub to HS bus.
A "Single-TT" hub (also called "per hub") device has one TT in the controller, and a "Multi-TT" hub (also called "per port") device has one TT for each port in the controller.
"Multi-TT" hub enables 12 Mbps bandwidth for each downstream port theoretically.
In reality, many devices, such as PC-cam, USB speaker and storage device which may require higher bandwidth, can operate simultaneously under "Single-TT" hub, without performance trouble.
Suitable Products
USB2.0 Hub Controller
UPD720115
UPD720114
UPD720113
UPD720112
UPD720110A
UPD720110