Re: More than 60% efficiency 5W travel charger



dagmargoodboat@xxxxxxxxx wrote:
Fred Bloggs wrote:

Bob J. wrote:

Hi all,

This efficiency is under 58%.

http://my.dreamwiz.com/jyeonsuk/qna/0106021801.jpg

My questions are two.

One is that it can be increased more than 60% efficiency?
The other is that are there any other way not using MCU with more than
60% efficiency?

This is a battery charger supply with MCU controlled constant voltage,
constant current mode. The most direct route to efficiency improvement
is through a modern LDO in CV mode with tight preregulation by the PWM
regulator, with low loss current monitoring and limiting operation. See
Linear Technology for the applicable class of regulation feature
availability.


Why not dump the linear regulator altogether and do as Tim suggests,
controlling and using the switcher directly to charge the battery?
That saves cost and cuts dissipation too.

Cheers,
James Arthur


The circuit is an off-line battery charger that uses an MCU together with linear components to execute some kind of multistage battery charger algorithm such as CC->CV->CV,trickle w/cutout at Imin; it very well could be for LiPo. The so-called efficiency probably degrades somewhat during the low output current CV trickle phase due to the regulator circuit overhead, and is not a constant.

.

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