REF: BBONEBLK_SRM
BeagleBone Black System
Reference Manual
Rev A5.2
Page 61 of 108
Ethernet PHY Power, Reset, and Clocks
Figure 39
show the power, reset, and lock connections to the
LAN8710A
PHY. Each of
these areas is discussed in more detail in the following sections.
PHY_VDDCR
PHY_XTAL2
PHY_XTAL1
PHYX
REFCLKO
C135
0.1uf ,6.3V
C131
0.1uf ,6.3V
C132
0.1uf ,6.3V
R131
100,1%
R142
0,1%
FB4
150OHM800mA
1
2
R143
10,1%
C143
30pF,50V
U14
LAN8710A
nRST
19
XTAL1/CLKIN
5
XTAL2
4
GN
D
_E
P
33
VD
D
IO
12
VD
D
1A
27
VD
D
2A
1
VD
D
C
R
6
RXCLK/PHYAD1
7
R140 0,1%,DNI
C134
1uF,10V
C142
30pF,50V
Y3
25.000MHz
XTAL150SMD_125X196
1
2
C136
470pF,6.3V
R124
10,1%,DNI
R141
1M,1%,DNI
DGND
VDD_PHYA
VDD_3V3B
DGND
DGND
DGND
DGND
DGND
DGND
DGND
SYS_RESETn
3,11
RMII1_REFCLK
4
C133
10uF,10V
RCLKIN
Figure 39.
Ethernet PHY, Power, Reset, and Clocks
6.8.2.1
VDD_3V3B Rail
The VDD_3V3B rail is the main power rail for the
LAN8710A
. It originates at the
VD_3V3B regulator and is the primary rail that supports all of the peripherals on the
board. This rail also supplies the VDDIO rails which set the voltage levels for all of the
I/O signals between the processor and the
LAN8710A
.
6.8.2.2
VDD_PHYA Rail
A filtered version of VDD_3V3B rail is connected to the VDD rails of the LAN8710 and
the termination resistors on the Ethernet signals. It is labeled as
VDD_PHYA
. The
filtering inductor helps block transients that may be seen on the VDD_3V3B rail.
