AD9520-5 PLL

I haven't found the way to set the prescaler of AD9520-5 to 1. In datasheet says that prescaler in fixed division can be set to 1, 2 or 3. But also below the "VCO/VCXO Feedback Divider N: P, A, B, R" says that P can be 2, 4, 8, 16 or 32. I have a 100 MHz VCXO connected to CLK input and I tried to start phase detector working at this frequency (reference clock is the same 100 MHz from external generator). If I set STATUS pin control = 4 or 1 (prescaler output or N divider output) I see divided by 2 frequency. If I set STATUS pin control = 2 (R divider output) I see 100 MHz. Bits 0-2 of 016 register = 0. Bit 0 of 1E1 register is 1 (bypass the VCO divider). Where's true?