5. Pin Description
8
7
6
1
2
3
VDDO
CLKOUT3
CLKOUT2/REFOUT2/
OE
VDD
XIN/CLKIN
XOUT
Si51218
4 5
VSS
CLKOUT1/
REFOUT1/OE
Figure 5.1. 8-Pin TDFN
Table 5.1. Si51218 8-Pin Descriptions
Pin # Name Type Description
1 VDD PWR 2.5 to 3.3 V power supply.
2 XOUT O Crystal output. Leave this pin unconnected (floating) if an external
clock input is used.
3 XIN/CLKIN I External crystal and clock input.
4 CLKOUT1/REFOUT1/OE I/O Programmable CLKOUT1 or REFOUT1 output or OE control in-
put. The frequency at this pin is synthesized by the internal PLL if
programmed as CLKOUT1. If programmed as REFOUT1, the out-
put clock is a buffered output of the crystal or reference clock in-
put.
5 VSS GND Ground.
6 CLKOUT2/REFOUT2/OE I/O Programmable CLKOUT2 or REFOUT2 output or OE control in-
put. The frequency at this pin is synthesized by the internal PLL if
programmed as CLKOUT2. This output clock can also be the buf-
fered output (REFOUT2) of the crystal or reference clock input. It
is powered by the V
DDO
pin (pin 8).
7 CLKOUT3 O Programmable CLKOUT3 output. The frequency at this pin is syn-
thesized by the internal PLL. It is powered by the V
DDO
pin (pin 8).
8 VDDO PWR 1.8 to 3.3 V output power supply to CLKOUT2/3 (pin 6/7).
Si51218 Data Sheet
Pin Description
silabs.com | Smart. Connected. Energy-friendly. Rev. 1.1 | 7
