Hello team,
I have a question about LMX2594.
My customer has two EVMs and set 12GHz output setting along with datasheet recommendation; VCO_SEL=4, VCO_DACISET_STRT=300 and VCO_CAPCTRL_STRT=1.
However, two EVMs show different VCO selection behavior like below table. One EVM behaves that VCO5 is always selected. but another EVM shows that VCO is selected alternately between VCO4 and VCO5 ever time FCAL_EN is sent.
EVM#1 | 1st | 2nd | 3rd | 4th | 5th | 6th |
rb_VCO_SEL | 5 | 4 | 5 | 4 | 5 | 4 |
rb_VCO_CAPCTRL | 183 | 1 | 183 | 1 | 183 | 1 |
rb_VCO_DACISET | 195 | 235 | 195 | 235 | 195 | 235 |
EVM#2 | 1st | 2nd | 3rd | 4th | 5th | 6th |
rb_VCO_SEL | 5 | 5 | 5 | 5 | 5 | 5 |
rb_VCO_CAPCTRL | 182 | 182 | 182 | 182 | 182 | 182 |
rb_VCO_DACISET | 227 | 228 | 228 | 229 | 229 | 229 |
Settings are; Oscin=125MHz, Fpd=62.5MHz, N divider=192, Fvco=12GHz VCO output, integer mode, PFD_DLY_SEL=1, FCAL_LPFD_ADJ: Fpd>=10, FCAL_HPFD_ADJ: Fpd<=100, CAL_CLK_DIV: Div2.
Although I think VCO5 has to be selected at 12GHz output, Is there any missing requirement?
Best regards,