AT43311

Features

Self-Powered Hub with Bus Power Controller

Full Compliance with USB Spec Rev 1.0

Full Speed USB Host Interface

Four Downstream Ports

Downstream Support for Full Speed and Low Speed Transfer Rates

Continual Monitoring of Port by System Host

Individual Port Power Control

USB Connection Status Indicators

6 MHz Oscillator with On-Chip PLL

Description

The AT43311 is a fully compliant USB hub chip with 5 ports, one upstream port and
four full/low-speed downstream ports. The AT43311 can be used as a stand alone or
can provide a simple and quick method of adding USB ports to an existing device.

As a repeater, the AT43311 provides upstream connectivity between the selected
function and the host. Connectivity involves setting up and tearing down connections,
handling bus faults, recovering from bus faults and detecting downstream device con-
nections and disconnections.

The AT43311 may also act as a hub controller managing the hub operations and
recording the status of the hub, bus transactions, and downstream ports. In this mode,
the AT43311 tracks and generates the bus enumeration, provides configuration infor-
mation to the host, provides individual port status to the host, and controls the port
operation based on host commands.

0738A-A

USB Hub

AT43311
Preliminary

Pin Configurations

SOIC/DIP/Cerdip

PWR2

PWR3

PWR4

VCC5

VSS

OSC1

OSC2

LFT

VCCA

OVL4

OVL3

OVL2

OVL1

VREF

GND

STAT4

PWR1

DP4

DM4

DP3

DM3

GND

DP2

DM2

VCC3

DP1

XDM1

DP0

DM0

STAT1

STAT2

STAT3

AT43311

Pin Description

Pin Type

Description

OSC1

Oscillator Input. Input to the inverting 6 MHz oscillator amplifier.

OSC2

Oscillator Output. Output of the inverting oscillator amplifier.

LFT

PLL Filter. For proper operation of the PLL, this pin should be connected through a
100

resistor and 10 nF capacitor to ground (V

) in parallel with a 2.2 nF capacitor

(see Figure 1Power Supply Connection).

VREF

Reference Voltage. This is an input pin that should be connected to an external
voltage source. VREF is used internally as the reference voltage by the overload
protection circuit to decide whether there is a problem with a port's power supply.

DP0

Upstream Plus USB I/O. This pin should be connected to VCC3 through an external
1.5K

pullup resistor. DP0 and DM0 form the full speed differential signal pin pairs

connected to the Host Controller or an upstream Hub.

DM0

Upstream Minus USB I/O

DP[1:4]

Port Plus USB I/O. These pins should be connected to VSS through external 1.5K

resistors. DP[1:4] and DM[1:4] are the differential signal pin pairs to connect
downstream USB devices.

DM[1:4]

Port Minus USB I/O. These pins should be connected to VSS through external 15K

resistors. DP[1:4] and DM[1:4] are the differential signal pin pairs to connect
downstream USB devices.

OVL[1:4]

Port Overload. These are the input signals used to indicate to the AT43311 that there
is a power supply problem with the port. If OVL is asserted, the AT43311 will assert
the corresponding PWR[1:4] pin and report the status to the USB Host.

PWR[1:4]

Power Switch. These are the output signals used to enable or disable the external
voltage regulator supplying power to the port. PWR[1:4] is de-asserted when a power
supply problem is detected at OVL[1:4].
For proper operation of PWR[1:4], an external pull-up resistor of 10K

to VCC5 is

required.

STAT[1:4]

Connect Status. These are output pins indicating that a port is properly connected.
STAT[1:4] is asserted when the port is enabled.

CC3

3.3V Power Supply, used for the USB interface

CC5

5V Power Supply, main power supply for the AT43311

CCA

5V Analog Power Supply

GND

Ground

AT43311

USB Hub Description

Hub Repeater

The hub repeater is responsible for port connectivity setup
and tear-down. The repeater also supports exception han-
dling such as bus fault detection and recovery, and con-
nect/disconnect detection.

When a SOP token is detected on the upstream port,
Port0, the AT43311 determines the speed of the transfer.
A USB hub must not propagate a full speed transfer to a
low speed port due to the possible misinterpretation of the
data. The AT43311 will propagate the packet to all enabled
downstream ports.

Note: See USB Specification for further detail on bus
states

The AT43311 supports downstream data signaling at both
1.5 Mbps and 12 Mbps. Devices attached to the down-
stream ports are either full speed or low speed depending
on which data line (DP or DM) is pulled high. If a port is
enumerated as low speed, the output buffers operate at a
slew rate between 75 ns and 300 ns. The AT43311 will not
propagate any traffic to that port unless it is prefaced with a
preamble PID. Low speed data following the preamble PID
is propagated to both low and full speed devices. The
AT43311 will enable low speed drivers within four full-
speed bit times of the last bit of a preamble PID, and will
disable the drivers at the end of an EOP. The upstream
traffic from any port to the host is propagated by Port0
using the full speed 4-20 ns slew rate drivers.

All ports are independently driven and monitored on the DP
and DM pins. The AT43311 detects or generates the `J',
`K', and SE0 bus signaling states. Each hub port has sin-
gle-ended and differential receivers on its DP and DM lines.
The ports' I/O buffers comply to the voltage levels and drive
requirements as specified in the USB Specifications Revi-
sion 1.0.

The Hub Repeater implements a frame timer that is timed
by the 12 MHz USB clock and is reset every time an SOF
token is received from the Host.

Hub Controller

The hub controller manages and records the operations of
the AT43311. During enumeration, the controller sends the
host the configuration information. The controller also
allows the host to retrieve the status of the downstream
ports, and power the downstream ports. The controller
applies power to the downstream ports on a per port basis.
After configuration, the controller will enable the power to a
downstream port upon a SetPortPower command by the
host. The controller supports two endpoints and a Control
Status register.

Serial Interface Engine
The Serial Interface Engine (SIE) converts data between
the serialized USB format and usable data for the controller
and repeater. To carry out these tasks, the SIE is able to
detect or generate USB signaling. Once a valid operation is
detected, the SIE translates the data depending on the
operation.

During a reception, the SIE will use the high speed clock
supplied by the PLL to help synchronize and separate the
synchronization information from the data. The data must
be decoded before the SIE may supply the packet ID to the
controller and repeater.

The USB protocol uses Cyclical Redundancy Check
(CRC), Non Return to Zero Invert (NRZI) data encoding
and bit stuffing to improve the reliability of data transfers.
The SIE must decode the NRZI and strip off the stuffed bit
to determine the actual data. The CRC information will be
used by the SIE to determine if a transmission error has
occurred. If an error has occurred, the SIE will correct the
data using CRC algorithms.

Control Status Register

Bit

Function

Value

Description

Hub configuration status

0
1

Set to 0 or 1 by a Set_Configuration Request

Hub is not currently configured
Hub is currently configured

Hub remote wakeup status

0
1

Set to 0 or 1 by ClearFeature or SetFeature request
Default value is 0

Hub is currently not enabled to request remote wakeup
Hub is currently enables to request remote wakeup

Endpoint0 STALL status

0
1

Endpoint0 is stalled
Endpoint0 is stalled

Endpoint1 STALL status

0
1

Endpoint1 is not stalled
Endpoint1 is stalled

AT43311

Status Change Register

Bit

Function

Value

Meaning

Hub status change

0
1