The switching regs use ac don't they ?
If so, how would you run them from battery ?

----- Original Message -----=20
From: "SkinTech" <jan.didden@SKINTECH.BE>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Sunday, July 22, 2001 7:26 PM
Subject: Re: [PICLIST] [OT]: How to reduce power consumption for battery =
operated circuits?


> Hi John,
>=20
> Actually if the current drain is zero, the regulator consumes only its =
own
> standby current, it doesn't 'syphon off' the excess voltage in any =
way. It
> does carry the same current as the load, so if you draw 1 amp, the =
excess 2
> volts (which will appear across the reg) will waste 2v * 1 amp =3D 2 =
watts.
> The load gets 5v * 1 amp =3D 5 watts, giving you some 71% efficiency =
(only).
> This is independent of the load current. You get much better mileage =
with
> one of the modern switching low voltage regs, they have almost 100%
> efficiency (well yes, almost...).
>=20
> Cheers, Jan Didden
>=20
> ----- Original Message -----
> From: "John Waters" <john_fm_waters@HOTMAIL.COM>
> To: <PICLIST@MITVMA.MIT.EDU>
> Sent: Sunday, July 22, 2001 6:17 PM
> Subject: [OT]: How to reduce power consumption for battery operated
> circuits?
>=20
>=20
> > Hi All,
> >
> > For a battery operated circuit, we want the power consumption to be =
as low
> > as possible, but if the circuit involves a microcontroller, we will =
need a
> > voltage regulator like the 78L05 or 7805 to keep the 5V stable. =
Since the
> > supply voltage is at least 2V higher than the 5V, part of the =
current will
> > be bypassed through the regulator, in other words, the regulator
> "consumes"
> > some power even when there is no or little current demanding by the
> > microcontroller circuit itself.
> >
> > Is using the regulator unavoidable? What is the usual methods to =
reduce
> > power consumption for a battery operated microcontroller circuit?
> >
> > Thanks in advance!
> >
> > John
> >
> >
> >
> >
> >
> > _________________________________________________________________
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>=20
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>=20
>=20
>=20

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