power opamp?

[Joerg]

Don't know who is staying. I sent an E-mail to my last device model
contact... no response. So I'll call the rep and find out what's
going on.

The no response thing is unfortunately becoming somewhat normal. I am
still waiting for some app EE answers. More than a week now. They don't
even send an acknowledge email anymore and when I called I was told that
my case is "in progress". Things are not looking up for some US
semiconductor places unless they fix that, and pronto. Seems like mnany
of those companies aren't run by engineers anymore and that would be bad
news. For them, because us guys just move on. My clients don't want to
wait weeks.

 

[Jim Thompson]

Jim Thompson wrote: [snip]

Don't know who is staying. I sent an E-mail to my last device model
contact... no response. So I'll call the rep and find out what's
going on.

The no response thing is unfortunately becoming somewhat normal. I am
still waiting for some app EE answers. More than a week now. They don't
even send an acknowledge email anymore and when I called I was told that
my case is "in progress". Things are not looking up for some US
semiconductor places unless they fix that, and pronto. Seems like mnany
of those companies aren't run by engineers anymore and that would be bad
news. For them, because us guys just move on. My clients don't want to
wait weeks.

I complained too soon. My contact now has another job, and forwarded
my E-mail to the present keeper of IP, who replied just in the last
few minutes.

...Jim Thompson

 

[JosephKK]

I'll trade my entire stock of ferrite beads for one indecent model.

Did you make an assumption about gender or age?

 

[Rene Tschaggelar]

What's a good medium-power opamp? I need to source/sink at least 60
mA, with say +-7.5 volt supplies, and swing +-6 maybe. No particular
requirements otherwise.

I suppose I could boost a cheap SOT-23 opamp with a couple of cheap
SOT-23 emitter followers....


v+
|
c
\ +----Rb---b npn
\ | e
\ | |
\---------+----Rx----+-------
/ | |
/ | e
/ +----Rb---b pnp
c
|
v-

John,
you'll get better rail performance when you connect
a PNP above and an NPN below and pull their respecive
base from the supply through a resistor with the power
connections of the Amp itself. The current not provided
by the Amp is delivered by the Transistors.
What ist the requeired bandwidth?


V+ V+
| |
R e
+---b PNP
\ | c
\ |
\ |
--+-----
/ |
/ |
/ | c
+---b NPN
R e
| |
V- V-


Rene

 

[MooseFET]

John,
you'll get better rail performance when you connect
a PNP above and an NPN below and pull their respecive
base from the supply through a resistor with the power
connections of the Amp itself. The current not provided
by the Amp is delivered by the Transistors.
What ist the requeired bandwidth?

V+ V+
| |
R e
+---b PNP
\ | c
\ |
\ |
--+-----
/ |
/ |
/ | c
+---b NPN
R e
| |
V- V-

If you really want it to do rail to rail:

v+
| v+
R |
| e
\VCC----------------------b pnp
\ c
\ R1 |
\-------+--/\/\------+-------OUTPUT
/ ! |
/ -/\/\--GND !
/ R2 c
VEE---------------------b npn
| e
R |
| v-
v-

 

[Jim Thompson]

John,
you'll get better rail performance when you connect
a PNP above and an NPN below and pull their respecive
base from the supply through a resistor with the power
connections of the Amp itself. The current not provided
by the Amp is delivered by the Transistors.
What ist the requeired bandwidth?


V+ V+
| |
R e
+---b PNP
\ | c
\ |
\ |
--+-----
/ |
/ |
/ | c
+---b NPN
R e
| |
V- V-


Rene

Rene, You're way behind. I posted that configuration six days ago...

From: Jim Thompson <[email protected]>
Newsgroups: sci.electronics.design
Subject: Re: power opamp?
Date: Sun, 02 Mar 2008 14:50:36 -0700
Message-ID: <[email protected]>


...Jim Thompson

 

[Rene Tschaggelar]

Rene, You're way behind. I posted that configuration six days ago...

From: Jim Thompson <[email protected]>
Newsgroups: sci.electronics.design
Subject: Re: power opamp?
Date: Sun, 02 Mar 2008 14:50:36 -0700
Message-ID: <[email protected]>


...Jim Thompson

Sorry Jim,
you're right. I realized that after having read
a few more messages than I did at the beginning.

Rene

 

[Jim Thompson]

Jim Thompson wrote:
[snip]

Rene, You're way behind. I posted that configuration six days ago...

From: Jim Thompson <[email protected]>
Newsgroups: sci.electronics.design
Subject: Re: power opamp?
Date: Sun, 02 Mar 2008 14:50:36 -0700
Message-ID: <[email protected]>


...Jim Thompson

Sorry Jim,
you're right. I realized that after having read
a few more messages than I did at the beginning.

Rene

No problem. I'm glad someone else mentioned it. It's reasonably
stable when tied to the OpAmp output.

I used a similar configuration in the early '70's, no NPN, R to ground
from OpAmp output, PNP directly to load (not tied to OpAmp output),
741 OpAmp, to make LDO's for the TOW missile, built as a hybrid in a
TO-3 package ;-)

...Jim Thompson