5

SP5301DS/10

SP5301 Universal Serial Bus Transceiver

© Copyright 2000 Sipex Corporation

DESCRIPTION

The SP5301 is a half-duplex Universal Serial

Bus (USB) differential transceiver that interfaces

with the VHDL Serial Interface Engine (SIE)

from the USB developer's conference. The

SP5301 is designed to allow digital logic to

communicate with the physical layer of the

Universal Bus.

The USB is a cable bus that supports data

exchange between a host computer and a wide

range of peripherals. Attached peripherals share

USB bandwidth through a host scheduled token

based protocol. The USB allows peripherals to be

attached, configured, used, and detached while

the host and other peripherals are in operation.

This is referred to as dynamic, or hot, attachment

and removal. USB attributes include lower costs,

hot plug-and-play with dynamic attach-detach

capabilities, ease of design and use, multiple

peripherals, guaranteed latency, and guaranteed

bandwidth.

The USB is specified to be an industry standard

extension to the PC architecture with a focus on

Computer Telephony Integration (CTI),

consumer, and productivity applications. The

architecture of the USB protocol can ease the

expansion of PC peripherals, provide a low-cost

solution that supports tranfer rates up to 12Mbps,

and can fully support real-time data for voice,

audio, and compressed video.

The USB protocol can provide protocol flexibility

for mixed-mode isochronous data transfers and

asynchrounousmessaging.Guaranteedbandwidth

and low latencies are appropriate for many

telephony and audio applications. A 12Mbps bus

covers the mid-speed and low-speed data ranges.

Typically, mid-speed data types are isochronous

and low-speed data comes from interactive

devices. Isochronous communication can only

be used by full speed devices.

THEORY OF OPERATION

The USB protocol can support multiple

connections for up to 127 physical devices

composed of many diverse functions. This makes

the SP5301 an ideal solution for multidrop

applications. This lower protocol overhead

results in high bus utilization. An isochronous

workload may utilize the entire USB bus

bandwidth. The USB protocol reflects a robust

capability of dynamic insertion and removal of

devices identified in user perceived real-time.

This PC plug and play quality preserves the

marketable synergy with the PC industry, being

a simple protocol to implement and integrate

into existing operating systems.

The SP5301 contains a differential driver

and a differential receiver in a half-duplex

configuration. The driver is enabled by the OE

pin. If OE is asserted LOW, the driver is active

and the D- and D+ pins drive USB signals. The

differential receiver is also controlled by the OE

pin. If OE is HIGH, while SUSPEND is LOW,

the receiver is active and the driver is in tri-state.

In this receive mode, the D- and D+ pins are now

receiving USB signals.

The typical driver output voltage swing for

D- and D+ of the SP5301 will be less than +0.3V

for the LOW state and greater than +2.8V for the

HIGH state.

The SP5301 is a USB differential interface with

very high receiver input sensitivity. This makes

data virtually immune to noise on the USB

pipeline. The +90mV minimum receiver input

sensitivity of the SP5301 ensures recovery of

even severely attenuated signals.