GL852 USB 2.0 MTT HUB Controller

©2000-2007 Genesys Logic Inc. - All rights reserved.

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USB2.0 HOST/HUB

REPEATER

TT

USPORToperating

in HS signaling

HS vs. FS/LS:

Traffic channel

is routed to TT

HS vs. HS:

Traffic channel is

routed to REPEATER

DSPORT operating

in HS signaling

DSPORT operating

in FS/LS signaling

TT

Figure 5.2 - Operating in USB 2.0 scheme

5.12 DSPORT logic

DSPORT (downstream port) logic implements the control logic defined in section 11.5 of USB

specification Revision 2.0. It mainly manipulates the state machine, the connection/disconnection detection,

over current detection and power enable control, and the status LED control of the downstream port.

Besides, it also output the control signals to the DSPORT transceiver.

5.13 DSPORT Transceiver

DSPORT transceiver is the analog circuit that supports high-speed, full-speed, and low-speed electrical

characteristics defined in chapter 7 of USB specification Revision 2.0. In addition, each DSPORT

transceiver accurately controls its own squelch level to detect the detachment and attachment of devices.

5.2 Configuration and I/O Settings

5.2.1 RESET# Setting

GL852 integrates in the pull-up 1.5K

resister of the upstream port. When RESET# is enabled, the internal

1.5K

pull-up resister will be disconnected to the 3.3V power. To meet the requirement (p.141) of the USB

2.0 specification, pull-up resister should be disconnected while lacking of USB cable power (Vbus).

Therefore, we suggest designing the RESET# circuit as following figure to meet the requirement mentioned

above.