ADP2120 operating in a discontinuous mode when synchronized.

The circuit is synchronizing correctly. The schematic is essentially the same as the application circuit in the data sheet (figure 50) with L= 2.2uH inductor, Cin = 2x 1u, Cout = 2x 10u. The circuit appears to be operating in the Discontinuous conduction mode, not the PFM mode. I've inserted a couple scope shots of the switch waveforms.

As is, the circuit is generating a lot of low frequency noise. I believe this is due to the varying pulse width modulation. I want to get it to operate in the Continuous conduction mode where there should be less modulation of the inductor current. I *think* that increasing the inductor value should accomplish this. I would appreciate any info or links to any ADI documents that can offer insite into this.

The circuit is synchronizing correctly. The schematic is essentially the same as the application circuit in the data sheet (figure 50) with L= 2.2uH inductor, Cin = 2x 1u, Cout = 2x 10u. The circuit appears to be operating in the Discontinuous conduction mode, not the PFM mode. I've inserted a couple scope shots of the switch waveforms.

As is, the circuit is generating a lot of low frequency noise. I believe this is due to the varying pulse width modulation. I want to get it to operate in the Continuous conduction mode where there should be less modulation of the inductor current. I *think* that increasing the inductor value should accomplish this. I would appreciate any info or links to any ADI documents that can offer insite into this.