ADF4155 Int-N Mode

Hi ADI people,

Unlike ADF4159, there is no explicit control bit to disable the Σ-Δ modulator in ADF4155. Can ADF4155 be operated in true int-N mode? In the datasheet, it says: "If FRAC1 and FRAC2 = 0, the synthesizer operates in integer-N mode". If FRAC1 and FRAC2 are set to 0, does the Σ-Δ modulator keep running?