AT43312A-SU View Datasheet(PDF) - Atmel Corporation

Part Name

Description

Manufacturer

AT43312A-SU

Self- and Bus- powered USB Hub Controller

Atmel Corporation 

Port Status Pin

Hub Controller

AT43312A

Figure 3. Bus Powered Hub Power Supply

BUS_POWER

GND

U1

AT43312A

LPSTAT

U2

PORT POWER

IN

OUT

SWITCH

GND

To

Downstream

Device

The STATx pins are signals that is not required by the USB specification. Its function is

to allow the hub to provide feedback to the user whenever a device is properly con-

nected to the port. An LED and series resistor connected to STATx can be used to

provide a visual feedback. If an overcurrent condition is detected at a port, the STATx of

the offending port will alternately turn on and off causing an LED to blink. The LED will

continue to blink until power to the offending port is turned off by the host or until the hub

is re-enumerated.

The default state of STATx is inactive. After a port is enabled AT43312A will assert the

port’s STATx. Any condition that causes the port to be disabled inactivates STATx.

Note:

The I/O Pins of the AT43312A should not be directly connected to voltages less than

VSS or more than the voltage at the CEXT pins. If it is necessary to violate this rule,

insert a series resistor between the I/O pin and the source of the external signal source

that limits the current into the I/O pin to less than 2 mA. Under no circumstances should

the external voltage exceed 5.5V. To do so will put the chip under excessive stress.

The Hub Controller of the AT43312A provides the mechanism for the Host to enumerate

the Hub and the AT43312A to provide the Host with its configuration information. It also

provides a mechanism for the Host to monitor and control the downstream ports. Power

is applied, on a per port basis, by the Hub Controller upon receiving a command, Set-

PortFeature[PORT_POWER], from the Host. The AT43312A must be configured first by

the Host before the Hub Controller can apply power to external devices.

The Hub Controller contains two endpoints, Endpoint0 and Endpoint1 and maintains a

status register, Controller Status Register, which reflects the AT43312A’s current set-

tings. At power up, all bits in this register will be set to 0’s.

9

1255G–USB–05/06

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