S i 5 3 4 1 / 4 0
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Preliminary Rev. 0.9
6. Pin Descriptions
Table 17. Si5341/40 Pin Descriptions
Pin Name
Pin Number
Pin Type
1
Function
Inputs
XA
8
5
I
Crystal Input
These pins are used for an optional XTAL input when operating
the device in asynchronous mode (i.e. free-run mode). Alterna-
tively, an external reference clock (REFCLK) can be applied to
these pins. See "4.3.1. External Reference Input (XA/XB)" on
page 22. An external XTAL or REFCLK is not needed when oper-
ating in synchronous mode when the device is locked to an exter-
nal input clock through the clock input pins (IN0 to IN2). These
pins can be left unconnected when not in use.
XB
9 6
I
X1
7
4
I
XTAL Shield
Connect these pins directly to the XTAL ground pins. X1, X2, and
the XTAL ground pins should be separated from the PCB ground
plane. Refer to the Si5341/40 Family Reference Manual for layout
guidelines. These pins should be left disconnected when connect-
ing XA/XB pins to an external reference clock (REFCLK).
X2
10
7
I
Notes:
1.
I = Input, O = Output, P = Power.
2.
The IO_VDD_SEL control bit (0x0943 bit 0) selects 3.3 V or 1.8 V operation.
3.
The voltage on the VDDS pin(s) determines 3.3 V or 1.8 V operation.
GND
Pad
IN1
IN1
IN_SEL0
IN_SEL1
SYNC
RST
X1
XA
XB
X2
OE
INTR
VDDA
IN2
IN2
SCLK
A0/
CS
SD
A/
S
D
IO
A1/SDO
VD
D
RS
VD
RS
VD
VD
DO0
OU
T
0
OU
T
0
FD
E
C
OU
T
1
OU
T
1
VD
DO2
OU
T
2
OU
T
2
FINC
LOL
VDD
OUT6
OUT6
VDDO6
OUT5
OUT5
VDDO5
I2C_SEL
OUT4
OUT4
VDDO4
OUT3
OUT3
VDDO3
VD
DO7
OUT7
OUT7
VD
DO8
OUT8
OUT8
OUT9
OUT9
VD
DO9
VD
D
FB
_
IN
FB
_
IN
IN0
IN0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
48
47
46
45
44
43
42
41
40
39
38
37
36
35
34
33
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
64
63
62
61
60
59
58
57
56
55
54
53
52
51
50
49
VD
DO1
Si5341 64QFN
Top View
R
SVD
R
SVD
GND
Pad
IN1
IN1
IN_SEL0
INTR
X1
XA
XB
X2
OE
RST
VDDA
VDDA
IN2
A0
/C
S
SDA/SDIO
A1/SDO
OU
T0
OU
T0
V
DDO
0
SCL
K
I2C
_
S
E
L
OUT1
OUT1
VDDO1
VDDO3
OUT3
OUT3
FB_I
N
FB_I
N
IN
0
IN
0
Si5340 44QFN
Top View
1
2
3
4
5
6
7
8
9
10
33
32
31
30
29
28
27
26
25
24
12
13
14
15
16
17
18
19
20
21
44
43
42
41
40
39
38
37
36
35
VDD
OUT2
OUT2
VDDO2
VDDS
LOL
LOS_XAXB
VDD
IN_SEL1
IN2
11
23
NC
22
VDD
VDD
34