In Si5350A, is it possible to directly bypass XA(XTAL) input clock signals to output pad, without via PLL route? ClockBuilderPro could not be configured this PLL Bypassed Output.
Yes, it is possible, but you need to manually edit the register file.
For all its bloated size, ClockBuilder is quite brain-dead and lacking in full user controls.
It can export a table like this
0x0010[3:2] CLK0_SRC 3 0x3
but cannot read a simple ascii file that has that field edited.
3:2 CLK0_SRC[1:0] Output Clock 0 Input Source. These bits determine the input source for CLK0. 00: Select the XTAL as the clock source for CLK0. This option by-passes both synthesis stages (PLL/VCXO & MultiSynth) and connects CLK0 directly to the oscillator which generates an output frequency determined by the XTAL frequency. 01: Select CLKIN as the clock source for CLK0. This by-passes both synthesis stages (PLL/VCXO & MultiSynth) and connects CLK0 directly to the CLKIN input. This essentially creates a buffered output of the CLKIN input.
Thank you for providing the information. I will confirm the feasibility and details regading the custom configurations, to our tech support purson.
Si5350 does support PLL bypassed output. While CBPro doesn't support PLL bypass function currently(Si5350 is pin controlled chip and customer need customize the part number according to their frequency plan through CBPro). If you need set some outputs with PLL bypassed mode, please create saleforce case with your frequency plan to ask for application engineer's help as short term solution. For long term, I have requested to add PLL bypass mode in CBPro for Si5350 internally.
With the support of our agency's FAE person, I could confirmed that the custom projects configuring PLL bypass mode are available on Si5350A. We believe that the PLL bypass mode is useful such as PRO-AV equipments and/or some of SoC devices, that is required very low-jitter clock sources. Thank you for your cooperations.
Currently, we are verify the amount of jitter added by clock input sources (such as XTAL and/or TCXO) and Si5351A device by using Si535x-B20QFN-EVB.