Other Parts Discussed in Thread: LMK04906
Hi
We are successfully using an LMK04906 in our FPGA/ADC design. I am using it with a Crystek CVHD-950 100MHz VCXO.
Problem I have:
I found that the chip works fine as long as I do not program register R16. (XTAL_LVL). Reading the datasheet, I assume somehow writing to this register triggers it into xtal mode and overrides the vcxo functionality? This fact is not outlined in the datasheet or am I mistaken?
I use a VCXO and write incrementally (as described in the DS) registers R0--R16, R24...R30. set xtal_lvl to 0 (R16 value: 0x01550410).
The device then looses lock and won't get back to lock until reconfiguration. Writing only R0--R15, R24..R30 works just fine.
My configuration: (135MHz clock at clkin0, 125MHz clock out)
0x80160140,
0x80000320,
0x00000281,
0x80000322,
0x80000023,
0x00000284,
0x00000325,
0x05000006,
0x08000007,
0x01010008,
0x55555549,
0x114049AA,
0x17F1900B,
0x1B0C01AC,
0x2313604D,
0x1300000E,
0x8000800F,
//0x015504x10, <- this kills it
0x000000D8,
0x01010019,
0xAFA8001A,
0x1C0006DB,
0x0040051C,
0x0100033D,
0x0100033E
has anyone of you met similar problems? Or is it OK if I just don't touch R16. Suggestions?
thank you!