Silicon Laboratories SI5351A/B/C - Manual (Page 36)

S i 5 3 5 1 A / B / C
36 Preliminary Rev. 0.95
Reset value = 0000 0000
Register 22. CLK6 Control
Bit D7 D6 D5 D4 D3 D2 D1 D0
Name CLK6_PDN FBA_INT MS6_SRC CLK6_INV CLK6_SRC[1:0] CLK6_IDRV[1:0]
Type R/W R/W R/W R/W R/W R/W
Bit Name Function
7 CLK6_PDN Clock 7 Power Down.
This bit allows powering down the CLK6 output driver to conserve power when the out-
put is unused.
0: CLK6 is powered up.
1: CLK6 is powered down.
6 FBA_INT FBA MultiSynth Integer Mode.
Set this bit according to ClockBuilder Desktop generated register map file.
5 MS6_SRC MultiSynth Source Select for CLK6.
0: Select PLLA as the source for MultiSynth0.
1: Select PLLB (Si5351A/C only) or VCXO (Si5351B only) MultiSynth0.
4 CLK6_INV Output Clock 6 Invert.
0: Output Clock 6 is not inverted.
1: Output Clock 6 is inverted.
3:2 CLK6_SRC[1:0] Output Clock 0 Input Source.
These bits determine the input source for CLK6.
00: Select the XTAL as the clock source for CLK6. This option by-passes both synthe-
sis stages (PLL/VCXO & MultiSynth) and connects CLK6 directly to the oscillator
which generates an output frequency determined by the XTAL frequency.
01: Select CLKIN as the clock source for CLK6. This by-passes both synthesis stages
(PLL/VCXO & MultiSynth) and connects CLK6 directly to the CLKIN input. This essen-
tially creates a buffered output of the CLKIN input.
10: Reserved. Do not select this option.
11: Select MultiSynth 0 as the source for CLK6. Select this option when using the
Si5351 to generate free-running or synchronous clocks.
1:0 CLK6_IDRV[1:0] CLK6 Output Rise and Fall time / Drive Strength Control.
00: 2 mA
01: 4 mA
10: 6 mA
11: 8 mA