Subject: Re: Current Feedback Amp Questions
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Date: Tue, 24 Sep 2002 06:18:04 GMT
NNTP-Posting-Date: Tue, 24 Sep 2002 08:18:04 MET DST
> They suggested that part because of the high current output (1.1 A). The
> I need is only 1 or 2, so the minimal gain limit won't be a problem.
> The other device I was looking at was the Burr Brown OPA547 which is about
> same price as the LT1210 but can deliver only 0.5 A. I have an
> where I will need to deliver between 0.2 and 0.6 A depending on the
> installation. I'd like to use the LT1210, but am concerned about the
> sensitivity to the loads.
> To be more specific, the system I am designing will drive analog
> At some sites there is only one indicator but at others, there are as many
> seven. Some sites have a few feet separating the displays while at
> they may be three floors apart with thin (lilke 24 gage) wires connecting
> In other words, the system will see a variety of resistive and possibly
> capacitive loads.
> Should I trust the LT engineer?!?
I know that applications engineers tend to push their parts into any design.
But this is quite strange to recommend a 35MHz part for DC, which consumes
around 50mA and has a lot of offset and noise. I do not know the price of
this gadget, certainly quite a bit.
Instead use a discrete output stage (AOE pg.186) with a normal precision
opamp. This is not short circuit proof, but if you choose separate power
regulators for this stage, they will limit the current to 1.5A.
You should also have a look at integrated audio power amps, which can
deliver the current at little cost. Have also a look at National Semi for
LM12 and Silicon General for SG1173.
Another disadvantage with a single sourced part is, any moment it can be
discontinued and then you have to do the above anyways.