why and when do we use DCM mode of DC DC converters

Dear All,
Can anybody tell me why and when do we use DCM mode of DC DC converters. Specifically Buck-Bosst converter?
Has it got anything to do with low power & low current applications. most of the converters i have encountered in low power application like energy harvesting, use converters in DCM mode. I was wondering why?

I hope the DCM is useless for DC-DC converters and it may not have any relationship with low current operation of the converters.
Regards,

DCM has a smaller inductor, and therefore cheaper. The resultant ripple is higher though.

DCM also avoids the LHP zero on boost derived converters. Thus feedback compensation is simpler to implement.

schmitt trigger said:

DCM has a smaller inductor, and therefore cheaper. The resultant ripple is higher though.

DCM also avoids the LHP zero on boost derived converters. Thus feedback compensation is simpler to implement.

Click to expand...

These are the main reasons.

A lot depends on the application and the power level.
If the output load can drop right down to near zero, then operating in DCM mode is unavoidable.

DCM is very easy to make stable under all operating conditions, and if the operating conditions can be pretty wide or unpredictable it can be a good choice.

If there is a fairly constant load, then CCM will usually lead to a much more efficient design because the peak current and ripple will be far less.

I recently built some 1.8Kw DCM buck boost converters for directly driving an inverter from some solar panels (without a battery).
The input voltage is all over the place from zero to about 255v.
Load goes from zero to 1.8Kw, and fluctuates as the inverter input current cycles through each half cycle.
DCM mode gives very fast response to sudden inverter load changes when big loads switch on and off, the transient response and regulation are fantastic.