VSC8641XKO Vitesse Semiconductor Corp, VSC8641XKO Datasheet - Page 70

• Manufacturer Part Number: VSC8641XKO
• Description: IC PHY 10/100/1000 100-LQFP
• Manufacturer: Vitesse Semiconductor Corp
• Type: PHY Transceiverr

Specifications of VSC8641XKO

• Number Of Drivers/receivers: 1/1
• Protocol: Gigabit Ethernet
• Voltage - Supply: 2.5V, 3.3V
• Mounting Type: Surface Mount
• Package / Case: 100-LQFP
• Case: TQFP
• Dc: 07+
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: 907-1031

Table 51.
4.5
4.5.1
Revision 4.3
August 2009
CMODE Resistor Values and Resultant Bit Settings (continued)
Using resistors with the CMODE pins can be optional in designs that access the device’s
MDC/MDIO pins. In designs that do this, all configurations otherwise affected on the
device by using the CMODE pins can be changed using the regular device register
settings, and all the CMODE pins can be pulled to VSS (ground). However, the
PHYADDR[4:0] still requires CMODE configuration.
EEPROM
The VSC8641 device EEPROM interface makes it possible to set up the device to self-
configure its internal registers based on the information programmed into and stored in
an external device. To accomplish this, the EEPROM is read on power-up or de-assertion
of the NRESET bit. For field configuration, the EEPROM can also be accessed using
VSC8641 device registers 21E and 22E.
The EEPROM used to interface to the VSC8641 device must have a two-wire interface. A
device such as the Atmel part AT24CXXX is suggested.
As defined by the interface, data is clocked from the VSC8641 device on the falling
edge of EECLK. The device determines that an external EEPROM is present if EEDAT is
connected to a 4.7 kΩ external pull-up resistor. The EEDAT pin can be left floating or
grounded to indicate that no EEPROM is present.
EEPROM Contents Description
When an EEPROM is present, the VSC8641 device looks for the command header,
0xBDBD at address 0 and 1 of the EEPROM. The address is incremented by 256 until
the header is found. If the header is not found or no EEPROM is connected, the
VSC8641 device bypasses the EEPROM read step.
When an EEPROM is present, the VSC8641 device waits for an acknowledgement for
approximately three seconds (in accordance with the ATMEL EEPROM protocol). If there
is no acknowledgement for three seconds, the VSC8641 device aborts its attempt to
connect to the EEPROM and reverts to its otherwise normal operating mode.
After the header value is found, the two-byte address value shown in the following table
indicates the EEPROM word address where the base address location for the device is
located. At the base address location, the next set of bytes indicates where the
configuration data contents to be programmed into the VSC8641 device are located. At
the programming location, the first two bytes represent the total number of bytes (11
bits long, with MSB first) where the Total_Number_Bytes[10:0] is equal to the number
of SMI writes multiplied by 3 (one byte for SMI port and register address and two bytes
With CMODE
Pin Tied To
VDD33
VDD33
VDD33
VDD33
With 1%
Resistor
8.25 kΩ
12.1 kΩ
16.9 kΩ
22.6 kΩ
Value
Bit 3 (MSB) to:
Set
1
1
1
1
Bit 2 to:
Set
1
1
1
1
Bit 1 to:
Set
0
0
1
1
VSC8641 Datasheet
Bit 0 (LSB) to:
Configuration
Set
0
1
0
1
Page 70