Low current 5v voltage regulators?

[bioroids]

Hi everybody:

 Does anyone knows about a low quiescent current voltage regulator?

 According to the 78L05 datasheet it consumes like 6mA, a little too much for a low current pedal design I'm trying to make. I need it to deliver no more than 5 or 6mA to the effect (the 78L05 can give up to 100mA)

 Any help is welcomed.

 And while we are at it, how can I calculate the duration of a 9v battery on a 6mA consumption?

 Thanks a lot

 Luck

 Miguel

[Mark Hammer]

I don't know anything about a low quiescent current regulator chip though there must definitely be some because there are all manner of digital thingies that need to run reliably off a steady 5v (very often a pair of 3v lithium cells) for very long periods of time.  Of course, those sorts of applications may make such chips SMT types which may well be the larger stumbling block.

You don't need to restrict yourself to 3-pin regulators, though.  There are all manner of regulation circuits out there using discrete components that can probably do what you want without involving too much more in the way of parts or cost.

How long can a battery last?  Batteries are often rated in ampere hours.  So a 3000maH battery (unlikely to be found in a 9v package) could supply 3 amps for an hour, 3ma for a thousand hours, 10ma for 300hrs, and so on.  I have no idea what the ampere-hours rating is on any of the name brand 9v's but you could probably find out.  I wouldn't expect much luck with any of the no-name generic types unless you had very good industry connections.  Many industrial suppliers will list ampere hours in their catalogs, though, for all the big names like Eveready, Duracell, Rayovac, and Mallory.

[cd]

An alkaline 9V is around 500mAh, carbon zinc around 250mAh.  That rating though is usually down to 1.2V.  The useful range for a guitar effect might be down to 8V, so take the mAh rating with a large grain of salt.

[bioroids]

Thanks for the info!

Mark, I like the idea of using discrete components to do the regulation, can you point me to any circuit? Maybe the standard zener-transistor circuit? I'll google for that also

I don't have any industry connections, so all I can do is check the Web. Or may be interesting also to run some tests on a few batteries.

Cd, that raises another question:

How low can get the battery and still expect the effect to work? I suppose it varies with the effect.

As a user, I think 7v may be a reasonable number, what do you guys think?

Good luck

[gez]

I use National's LP2950CZ-5.0 in just about everything I build nowadays - well, it seems like that!

Quiescent current is a mere 75 uA and they're low drop.  Data sheet here:

http://www.lynxmotion.com/images/data/lp2950.pdf

They're slightly noisy and need filtering (simple RC combo does the trick), but they do the job really well.

[bioroids]

Great info! I wonder if I can find those here

Thanks

Miguel

[gez]

The company who linked to the data sheet are in the US and sell them for $0.95, perhaps you could order from them?

http://www.lynxmotion.com/Search.aspx?txtSearch=LP2950CZ-5.0

[Paul Perry (Frostwave)]

Elko - Arrow
Constitucion 3040
Capital Federal , Buenos Aires C1254AAZ  tel: +54 11 6777-3500
fax: +54 11 6777-3500

That's the local National Semi distributor!

[bioroids]

Thanks Paul!

They have the regulator indeed, and not too expensive (0.6 U$S if I recall correctly) so I think I'm gonna try it soon.

Thanks Gez for the info!

Luck

Miguel