[Martin Griffith]

http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1040,C1055,P86471

martin

 

[Martin Griffith]

Wow, that 'typical application' internal schematic is a new low for LTC.
What is it, germanium?

Cheers,

Phil Hobbs

Don't have a clue (quite normal).

martin

 

[Joerg]

http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1040,C1055,P86471

martin

Thanks, but rather not. Quote "Using series resistance between the power
supply and the input of the LT3085 also stabilizes the application.
As little as 0.1Ω to 0.5Ω, often less, is all that is needed to provide
damping in the circuit. If the extra impedance between the power supply
and the input is unacceptable, placing the resistors in series with the
capacitors will provide damping to prevent the LC resonance from causing
full-blown oscillation."

 

[Martin Griffith]

Thanks, but rather not. Quote "Using series resistance between the power
supply and the input of the LT3085 also stabilizes the application.
As little as 0.1? to 0.5?, often less, is all that is needed to provide
damping in the circuit. If the extra impedance between the power supply
and the input is unacceptable, placing the resistors in series with the
capacitors will provide damping to prevent the LC resonance from causing
full-blown oscillation."

I had to try

One day they will make one that you like

martin

 

[David L. Jones]

http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1003,C1040,C1...

What's the bet they have a patent pending? :->

Dave.

 

[Joerg]

I had to try

One day they will make one that you like

Maybe. But then it should not cost $2 and show zero stock at Digikey ;-)

Possibly someone should teach the movers and shaker in the semi biz to
hit the ground running and not come out of the gate too slow.

 

[Joerg]

It only manages low dropout if the control voltage is about 1.5 volts
above the power input voltage.

Well, that plus IIRC it needs a minimum load current. So does the LM317
but my roll-your-own versions don't.

Great, if you have it.

You could make it but then there comes a point where you might as well
design the whole regulator from scratch, and for less $$$.

John

who finally got the incredibly obtuse Linksys wi-fi thing to work. I
only had to reinit and reconfigure it six times.

Strange. Mine only needed one attempt. Hopefully it doesn't have a leaky
flash ...

 

[Joerg]

You don't believe the NPN output transistor symbol?

NPNs are too liberal ...

 

[Joerg]

My bad! Didn't read close enough. You _could_ use a charge pump to
accomplish such a task.

Ask CA politicians, they'll tell you how to do it without. Well, at
least up to now :-(

 

[Glen Walpert]

We recently "invented" the flying-capacitor "isolated" DC power
supply, using 300 volt SSRs in a DPDT configuration. They switch slow
enough that the spike situation should be pretty good, compared to
most dc/dc converters. And no transformers!

Have you seen Jim Williams AN-70 "A Monolithic Switching Regulator
with 100uV Output Noise"? He also trades switching speed (and a bit
of efficiency) for low noise.