Datasheet
78Q2120C
10/100BASE-TX
Transceiver
Page: 30 of 35 © 2009 Teridian Semiconductor Corporation Rev 1.3
FIGURE 1: TYPICAL APPLICATIONS CIRCUIT
Note 2: This application circuit is only
valid for the 78Q2120C09 revision.
Refer to Ordering Information for
revision identification.
R7 100
R3
49.9
1%
0603
C11
0.01
1.5KV
1808
R2
49.9
1%
0603
GND
R18
75
RXD3
INTERRUPT
RXD0
R1
5.1K
RXCLK
C2
0.1
LED10
68 ohm Impedance Traces
R17
75
GND
R8 100
C9 and C10 must be calibrated
in actual application board for
25.000MHz +/-50ppm.
TXEN
R9 100
LEDFD
J1
RJ45
1
2
3
4
5
6
7
8
9
10
TXCLK
R4
49.9
1%
0603
R12 100
R10 100
VCC
C1
0.1
LED100
VCC
CGND
C5
0.01
RXD2
COL
GND
R16
75
TXD1
R15
75
TXD0
R13
75
TXER
100 ohm
Impedance
Traces
Y1
25.000MHZ
50ppm
RXD1
LEDTX
Note 1
RXER
GND
C8
0.01
C12
0.1
GND
T1
TLA-6T103
TDK
SMT16
1
2
3
8
5
6
7
9
12
11
10
14
16
15
RD+
RD-
RDCT
NC1
RXCT
RX-
RX+
NC2
TXCT
TX+
TX-
TDCT
TD-
TD+
C4
0.1
LEDRX
GND
VCC
CRS
100 ohm
Impedance
Traces
C10
39pF
R14
75
RXDV
LEDL
1) Recommend to leave
pins 56 and 56 as NC for
78Q2120C09 device.
Connecting a resistor
between these pins as in
the 78Q2120C09 will have
no effect on this device
C9
39pF
TXD2
C6
0.1
R6 100
R11 100
LEDCOL
VCC
C3
0.1
U1
78Q2120C09-CGT
TSC
LQFP64
28
27
32
31
30
29
24
19
20
21
22
64
63
4
6
59
58
53
10
43
11
52
51
56
54
62
61
41
60
55
18
33
23
17
34
9
8
26
25
7
47
44
45
46
49
48
50
57
40
39
38
37
36
12
13
14
15
16
5
3
35
42
2
1
TXEN
TXCLK
TXD3
TXD2
TXD1
TXD0
RXCLK
RXD3
RXD2
RXD1
RXD0
PCSBP
VCC
CKIN
RST
XTLP
XTLN
GND
GND
VCC
VCC
RXIP
RXIN
NC
NC
TXON
TXOP
VCC
GND
GND
MDC
COL
RXDV
MDIO
CRS
GND
VCC
TXER
RXER
PWRDN
ANEGA
TECH2
TECH1
TECH0
LEDFDX
LEDBT
RPTR
VCC
LEDL
LEDTX
LEDRX
LEDCOL
LEDBTX
PHYAD4
PHYAD3
PHYAD2
PHYAD1
PHYAD0
GND
GND
INTR
GND
ISO
ISODEF
RESET
C7
0.01
MDIO
R5
49.9
1%
0603
TXD3
GND
MDC
VCC
GND
GND