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DS00001898A-page 21

USB3280

The receivers connect directly to the USB cable. The block contains a separate differential receiver for HS and FS mode.

Depending on the mode, the selected receiver provides the serial data stream through the mulitplexer to the RX Logic

block. The FS mode section of the FS/HS RX block also consists of a single-ended receiver on each of the data lines

to determine the correct FS LINESTATE. For HS mode support, the FS/HS RX block contains a squelch circuit to insure

that noise is never interpreted as data.

7.6

USB 2.0 Transceiver

The Microchip Hi-Speed USB 2.0 Transceiver consists of the High Speed and Full Speed Transceivers, and the Termi-

nation resistors.

7.6.1

HIGH SPEED AND FULL SPEED TRANSCEIVERS

The USB3280 transceiver meets all requirements in the USB 2.0 specification.

The receivers connect directly to the USB cable. This block contains a separate differential receiver for HS and FS

mode. Depending on the mode, the selected receiver provides the serial data stream through the multiplexer to the RX

Logic block. The FS mode section of the FS/HS RX block also consists of a single-ended receiver on each of the data

lines to determine the correct FS linestate. For HS mode support, the FS/HS RX block contains a squelch circuit to

insure that noise is never interpreted as data.

The transmitters connect directly to the USB cable. The block contains a separate differential FS and HS transmitter

which receive encoded, bit stuffed, serialized data from the TX Logic block and transmit it on the USB cable.

7.6.2

TERMINATION RESISTORS

The USB3280 transceiver fully integrates all of the USB termination resistors. The USB3280 includes the 1.5kΩ pull-up

resistor on DP. In addition the 45Ω high speed termination resistors are also integrated. These integrated resistors

require no tuning or trimming. The state of the resistors is determined by the operating mode of the PHY. The possible

valid resistor combinations are shown in Table 7-1.

• RPU_DP_EN activates the 1.5kΩ DP pull-up resistor

• HSTERM_EN activates the 45Ω DP and DM high speed termination resistors

FIGURE 7-7:

RECEIVE TIMING FOR DATA PACKET (WITH CRC-16)