Al salaam a'alaykum Bob

16 Nov 03 09:41, Bob Lawrence wrote to David Drummond:

 DD>> I had thought of using a "simple series regualtor" but this is
 DD>> intended to be used at my "country weekender" where I don't
 DD>> have mains. Battery life _is_ a consideration. 

 BL>  I haven't got the data sheets, but those little low-voltage IC
 BL> switch-modes struggle to get 50% efficiency, and at 50% to get 6.3 at
 BL> 3A you'll put in 12.6 at 3A... so what's the difference with a series
 BL> regulator? Even if you got 70% (a miracle, IMO) you'd put in 2.2A...

How does NatSem claim 70-80% efficieny for this thing then? (Later: yeah,
false advertising).

 BL>  The series regulator has other advantages (besides keeping your feet
 BL> warm on a cold night). The VCR motors take a high starting current
 BL> before they get the wheels turning, and that's *just* what a
 BL> switch-mode doesn't like.

What VCR? 

This is to run a small DVD player, which came with a mains switch-mode PSU.

Regards,
David

--- Msged/LNX TE 06 (pre)