SMSC LAN9303, Руководство пользователя, Страница: 4 / 10

LAN9303 Evaluation Board User Manual
Revision 1.0 (05-28-09)
USER MANUAL
SMSC LAN9303
4
2.1 Jumpers
The following tables describe the default settings and jumper descriptions for the EVB9303. These
defaults are the recommended configurations for evaluation of the LAN9303. These settings may be
changed as needed, however, any deviation from the default settings should be approached with care
and knowledge of the schematics and datasheet. An incorrect jumper setting may disable the board.
Note: A dashed line in the Settings column indicates the board’s default jumper setting.
2.1.1 JP1 - JP6
2.1.2 JP7 - JP18
Jumpers JP7 through JP18 set various functions of the LAN9303. They can also be used as GPIOs,
LED drivers, or interrupts. When used as LED drivers, as they are on the EVB9303, they are
connected a specific way to set the strap value to a “1”, and another way to set the strap value to a
“0”.
Figure 2.2 illustrates the schematic connections with the LED1 circuit as a pull-up, and the LED2
circuit as a pull-down. To illuminate LED1, the LAN9303 will drive the cathode of the LED1 low. To
illuminated LED2, the LAN9303 will drive the anode of the LED2 high.
The JP7 - JP18 jumpers must be configured in pairs to identical settings in order to realize the LED1
circuit or the LED2 circuit. The pairings are as follows:
„
JP7 & JP13
„
JP8 & JP14
„
JP9 & JP15
„
JP10 & JP16
Table 2.1 Jumpers JP1 - JP6
JUMPER DESCRIPTION SETTINGS
JP1
C5V DC power
supply
1---2
IN: C5V brick output to power
plane
OUT: Disc5V brick power
JP2 Power switch enable jumper
1---2 Enable power switch
2 3
Disable power switch, force power ON
always
JP3 C3.3V jumper 1---2
IN: C3.3V regulator output to
+3.3V power plane
OUT: Disc3.3V regulator
JP4 MDIO pull-up/down jumper
1---2 Connect MDIO to 1.5K pull-up to +3.3V
2 3 Connect MDIO to 2.5K pull-down to GND
JP5 MDC pull-down jumper 1---2
IN: Connect MDC to 10K pull-down
OUT: Disconnect MDC from 10K pull-
down
JP6 I
2
C connect jumper
1 2 Pins 1 and 2 are +3.3V
3---4 Connect I
2
C EEPROM to SDA
5---6 Connect I
2
C EEPROM to SCL
7---8 Pins 7 and 8 are GND