SI5341 Datasheet, PDF (42/56 Pages) Silicon Laboratories – LOW-JITTER, 10-OUTPUT, ANY-FREQUENCY, ANY-OUTPUT CLOCK GENERATOR

Si5341/40
Table 18. Pin Descriptions
Pin Name
Inputs
XA
XB
X1
X2
IN0
IN0
IN1
IN1
IN2
IN2
FB_IN
FB_IN
Pin Number
Pin Type¹
Si5341 Si5340
Function
8
5
9
6
7
4
10
7
63
43
64
44
1
1
2
2
14
10
15
11
61
41
62
42
I
Crystal and External Clock Input
I
These pins are used to connect an external crystal or an external
clock. See section “5.3.1. XA/XB Clock and Crystal Input” and
“Figure 11. XAXB External Crystal and Clock Connections” for
connection information. If IN_SEL[1:0] = 11b, then the XAXB input
is selected. If the XAXB input is not used and powered down, then
both inputs can be left unconnected. ClockBuilder Pro will power
down an input that is set as "Unused".
I
XTAL Shield
I
Connect these pins directly to the XTAL ground pins. X1, X2, and
the XTAL ground pins must not be connected to the PCB ground
plane. DO NOT GROUND THE CRYSTAL GROUND PINS. Refer
to the Si5341/40 Family Reference Manual for layout guidelines.
These pins should be left disconnected when connecting XA/XB
pins to an external reference clock.
I
Clock Inputs
I
These pins accept both differential and single-ended clock sig-
nals. Refer to "5.3.2. Input Clocks (IN0, IN1, IN2)" on page 30 for
I
input termination options. These pins are high-impedance and
I
must be terminated externally. If both the INx and INx (with over-
strike) inputs are un-used and powered down, then both inputs
I
can be left floating. ClockBuilder Pro will power down an input that
I
is set as "Unused".
I
External Feedback Input
I
These pins are used as the external feedback input (FB_IN/
FB_IN) for the optional zero delay mode. See "5.5.13. Zero Delay
Mode" on page 36 for details on the optional zero delay mode. If
FB_IN and FB_IN (with overstrike) are un-used and powered
down, then both inputs can be left floating. ClockBuilder Pro will
power down an input that is set as "Unused".
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 for the serial interface pins, control input
pins, and status output pins. Refer to the Si5341/40 Family Reference Manual for more information on register settings.
3. If neither serial interface is used, leave pins I2C_SEL, A1/SDO, and A0/CS disconnected and tie SDA/SDIO and SCLK
low.
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Rev. 1.0