power regulator efficiency

[sweethomela8]

Is there any issues with choosing a switching power regulator that can provide a lot more current than a circuit needs...

for example..

I chose a linear tech, switching regulator capable of delivering up to 8 amps max.
What if the circuit only needs 1 or 2 amps, based on the datasheet the efficiency of the regulator is much lower (60-70 %) around that current consumption. Will my circuit still work if this is the case? How does the efficiency affect the circuit?

 

[eldhose555]

For a (or any) circuit, the supply current should be greater than or equal to what the ckt needs for its proper working.

for example..

I chose a linear tech, switching regulator capable of delivering up to 8 amps max.

this means ur regulator have the capacity to drive a circuit which needs 8A current.

 

[dick_freebird]

Oversizing the regulator might cost you a little efficiency,
but realize there are often current demands that are more
than your datasheet test condition might indicate. For
example, some circuits draw more current during power-up
than in normal powered activity. And many devices' specs
ignore load current, and so on. You will want some upside.
Questions are, how much and how well do you know?

 

[FvM]

Apparently you are talking of a switching mode regulator (SMPS). Particularly synchronous designs that are forced to continuous mode may show a considerable effiency drop at lower currents. As said, the available current overhead may be desirable anyway. There are also controllers, that provide an additional "efficiency mode" at light loads, keeping the high efficiency over 2 or even three orders of current magnitude. But there's no free lunch. You usually pay with higher switching noise at lower currents.