Filter
Top Products
USB 2.0 Hi-Speed Hub Controller
Datasheet
Revision 1.0 (3-11-09) 52 SMSC USB251x
DATASHEET
8.2.1.35 Register FFh: Status/Command
8.2.2 I
2
C EEPROM
The I
2
C EEPROM interface implements a subset of the I
2
C Master specification (Please refer to the
Philips Semiconductor Standard I
2
C-Bus specification for details on I
2
C bus protocols). The SMSC
hub’s I
2
C EEPROM interface is designed to attach to a single “dedicated” I
2
C EEPROM, and it
conforms to the Standard-mode I
2
C specification (100 kbit/s transfer rate and 7-bit addressing) for
protocol and electrical compatibility.
Note: Extensions to the I
2
C specification are not supported.
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.
8.2.2.1 Implementation Characteristics
The hub will only access an EEPROM using the sequential read protocol.
8.2.2.2 Pull-Up Resistor
The circuit board designer is required to place external pull-up resistors (10 kΩ recommended) on the
SDA / SMBDATA & SCL / SMBCLK / CFG_SEL[0] lines (per SMBus 1.0 specification, and EEPROM
manufacturer guidelines) to VDD33 in order to assure proper operation.
8.2.2.3 I
2
C EEPROM Slave Address
The slave address is 1010000.
Note: 10-bit addressing is NOT supported.
8.2.3 In-Circuit EEPROM Programming
The EEPROM can be programmed via ATE (automatic test equipment) by pulling RESET_N low
(which tri-states the hub’s EEPROM interface and allows an external source to program the EEPROM).
BIT
NUMBER BIT NAME DESCRIPTION
7:3 Reserved Reserved
2 INTF_PW_DN SMBus Interface Power Down
‘0’ = Interface is active
‘1’ = Interface power down after ACK has completed
1 RESET Reset the SMBus Interface and internal memory back to RESET_N
assertion default settings.
‘0’ = Normal Run/Idle State
‘1’ = Force a reset of registers to their default state
0 USB_ATTACH USB Attach (and write protect)
‘0’ = SMBus slave interface is active
‘1’ = The hub will signal a USB attach event to an upstream device, and the
internal memory (address range 00h-FEh) is “write-protected” to prevent
unintentional data corruption.