Cypress CY7C68000A Operational Modes, DPLUS/DMINUS Impedance Termination, OpMode10 Description

CY7C68000A

Operational Modes

The operational modes are controlled by the OpMode signals. The OpMode signals are capable of inhibiting normal operation of the transceiver and evoking special test modes. These modes take effect immediately and take precedence over any pending data operations. The transmission data rate when in OpMode depends on the state of the XcvrSelect input.

OpMode[1:0]	Mode	Description
00	0	Normal operation
01	1	Non-driving
10	2	Disable Bit Stuffing and NRZI
		encoding
11	3	Reserved

Mode 0 enables the transceiver to operate with normal USB data decoding and encoding.

Mode 1 enables the transceiver logic to support a soft disconnect feature that tri-states both the HS and FS transmitters, and removes any termination from the USB, making it appear to an upstream port that the device is disconnected from the bus.

Mode 2 disables Bit Stuff and NRZI encoding logic so ‘1’s loaded from the data bus becomes ‘J’s on the DPLUS/DMINUS lines and ‘0’s become ‘K’s.

DPLUS/DMINUS Impedance Termination

The CY7C68000A does not require external resistors for USB data line impedance termination or an external pull up resistor on the DPLUS line. These resistors are incorporated into the part. They are factory trimmed to meet the requirements of USB 2.0. Incorporating these resistors also reduces the pin count on the part.

Document #: 38-08052 Rev. *G Page 3 of 15

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