KSZ8851SNL-Eval Evaluation Board User’s Guide
Rev. 1.1
Micrel, Inc.
April 21, 2010
9/11
4.3 Power Supply and Test Point Definition
The KSZ8851SNL-Eval is supplied from ex5.0V DC power through a Header (pin 1 at
JP1), this +5.0V DC input is converted to both +3.3V with a Micrel LDO voltage regulator (U3,
MIC5209BM) for 3.3VA analog power and VDD (option for 3.3V, 2.5V or 1.8V) with a Micrel LDO
voltage regulator (U4, MIC5209BM) for VDD_IO digital power. The KSZ8851SNL contains an
in1.8V LDO, to provide its core, analog and PLL voltages.
The KSZ8851SNL-Eval has four test points. They are defined in the following Table 4.
Test Point
Definition
TP1
1.8V digital core voltage output measurement from
KSZ8851SNL internal LDO
TP2
3.3V Power supply measurement for VDD_IO
TP3
3.3VA Power supply measurement for VDD_A3.3
TP4
5.0V External power supply 5.0V_IN measurement
Table 4. KSZ8851SNL-Eval Test Point Definition
4.4 RJ-45 Connector and Transformer
The RJ-45 Jack (J1) connects to standard CAT-5 Ethernet cable to interface with 10Base-
T/100Base-TX Ethernet devices. The LAN interface on the KSZ8851SNL is connected to a
transformer (T1) with 50 ohm termination resistors for both TX+/- and RX+/- differential pairs. The
line side of the transformer is connected to the RJ-45 connectors (J1).
J1 also supports Auto-MDIX and Auto-Negotiation / Forced Modes.
4.5 EEPROM and LED Indicators
It is optional in the KSZ8851SNL to use an external EEPROM. The EED_IO (JP2) must be pulled
high (Jumper: ON) to use external EEPROM.
An external serial EEPROM with a standard microwire bus interface is used for non-volatile
storage of information such as the host MAC address. The KSZ8851SNL can detect if the
EEPROM is either a 1KB (93C46) or 4KB (93C66) EEPROM device. The EEPROM must be
organized as 16-bit mode.
The KSZ8851SNL EEPROM format is given in Table 5.
WORD
15 8
7 0
0H Reserved
1H
Host MAC Address Byte 2
Host MAC Address Byte 1
2H
Host MAC Address Byte 4
Host MAC Address Byte 3
3H
Host MAC Address Byte 6
Host MAC Address Byte 5
4H – 6H
Reserved
7H-3FH
Not used for KSZ8851SNL (available for user to use)
Table 5. KSZ8851SNL EEPROM Format
