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DS000002250A-page 15

USB2504/USB2504A

5.2.1

fer rate and 7-bit addressing) for protocol and electrical compatibility.

The Hub acts as the master and generates the serial clock SCL, controls the bus access (determines which device acts

as the transmitter and which device acts as the receiver), and generates the START and STOP conditions.

5.2.1.1

Implementation Characteristics

Please refer to the MicroChip 24AA00 DataSheet for Protocol and Programming specifics.

5.2.1.2

Pull-Up Resistor

The Circuit board designer is required to place external pull-up resistors (10K

 recommended) on the SDA/SMBDATA

& SCL/SMBCLK/CFG_SELO lines (per SMBus 1.0 Specification, and EEPROM manufacturer guidelines) to Vcc in

order to assure proper operation.

5.2.1.3

Slave address is 1010000.

5.2.2

IN-CIRCUIT EEPROM PROGRAMMING

The EEPROM can be programmed via ATE by pulling RESET_N low (which tri-states the Hub’s EEPROM interface and

allows an external source to program the EEPROM).

5.2.3

EEPROM DATA

Note:

Note:

10-bit addressing is NOT supported.

TABLE 5-1:

USER-DEFINED DESCRIPTOR DATA

Field

Byte

MSB:

LSB

Size

(Bytes)

Default

CFG

Self

(Hex)

Default

CFG

Bus

(Hex)

Description

VID

1:0

2

0424

0424

Vendor ID (assigned by USB-IF).

PID

3:2

2

4-port =

2504

4-Port =

2504

Product ID (assigned by Manufacturer).

DID

5:4

2

0000

0000

Device ID (assigned by Manufacturer).

Config Data

Byte 1

6

1

98

1C

Configuration data byte #1 for Hub options.

Config Data

Byte 2

7

1

90

90

Configuration data byte #2 for Hub options.

Non Removable

Device

8

1

00

00

Defines the ports that contain attached devices

(this is used only when Hub is part of a

compound device).

Port Disable

Self-Powered

9

1

00

00

Selects the ports that will be permanently

disabled

Port Disable

Bus-Powered

A

1

00

00

Selects the ports that will be permanently

disabled

Max Power

Self-Powered

B

1

01

01

Max Current for this configuration (expressed

in 2mA units).

Max Power

Bus-Powered

C

1

64

64

Max Current for this configuration (expressed

in 2mA units).