USB3500 datasheet(25/46 Pages) SMSC

25 / 46 page

Hi-Speed USB Host, Device or OTG PHY With UTMI+ Interface

Datasheet

SMSC USB3500

Revision 1.0 (04-04-05)

DATASHEET

6.4

USB2.0 Transceiver

The SMSC Hi-Speed USB2.0 Transceiver consists of four blocks in the lower left corner of Figure 2.1

on page 9. These four blocks are labeled HS XCVR, FS/LS XCVR, Resistors, and Bias Gen.

6.4.1

High Speed and Full Speed Transceivers

The USB3500 transceiver meets all requirements in the USB2.0 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.

6.4.2

Termination Resistors

The USB3500 transceiver fully integrates all of the USB termination resistors. The USB3500 includes

two 1.5kΩ pull-up resistors on DP and DM and a 15kΩ pull-down resistor on both DP and DM. In

addition the 45Ω high speed termination resistors are also integrated. These integrated resistors

require no tuning or trimming by the Link. The state of the resistors is determined by the operating

mode of the PHY. The possible valid resistor combinations are shown in Table 6.1. The RESISTOR

SETTINGS signals shown in the table are internal to the USB3500.

■

RPU_DP_EN activates the 1.5kΩ DP pull-up resistor

■

RPU_DM_EN activates the 1.5kΩ DM pull-up resistor

■

RPD_DP_EN activates the 15kΩ DP pull-down resistor

■

RPD_DM_EN activates the 15kΩ DM pull-down resistor

Figure 6.7 Receive Timing for Data Packet (with CRC-16)

USB3500 Datasheet(PDF) 25 Page - SMSC Corporation