Joachim....I was looking at simulation and BCP53/56 and it seems that we could improve noise performance by choosing different parts there.
I know you guys use the BC parts however these don't come as SMT parts.
Do you have any recommendation as far as SMD (TO261) is concerned?
I know you guys use the BC parts however these don't come as SMT parts.
Do you have any recommendation as far as SMD (TO261) is concerned?
Dual Die
BCM847BS, BCM857BS
SSM2212 and SSM2220
individuals
BC846B/C, BC856B/C (65V)
BC850B/C, BC860B/C (45V)
BCM847BS, BCM857BS
SSM2212 and SSM2220
individuals
BC846B/C, BC856B/C (65V)
BC850B/C, BC860B/C (45V)
interesting.
Thank you to you both.
Which one is better?
Also I have a question: some of the BJTs on the mirror have to dissipate 250mW, do you think that a SOT 23 package would be suitable for that?
Thank you to you both.
Which one is better?
Also I have a question: some of the BJTs on the mirror have to dissipate 250mW, do you think that a SOT 23 package would be suitable for that?
true, however don't want to unecessary parallel more BJT to complicate structure even more.
The beauty of this is its simplicity.
Do you think that 250mW is too much for a SOT23?
this one looks good too but I can see a SMT part for it
http://www.fairchildsemi.com/ds/SS/SS9014.pdf
http://www.fairchildsemi.com/ds/SS/SS9014.pdf
250mW is a lot for SMD.
I do not know if cooling helps.
There are cooling fins for SMD opamps that could work.
I do not know if cooling helps.
There are cooling fins for SMD opamps that could work.
should we go TO92? but that would be too much for it too, wouldn't it?
Yes cooling for OP AMPS seem to be a viable option too.
thanks for posting this ap note.
Here is a quote from it, which is basically all we need in this case
"The most cost effective approach of designing layout 2 0.066 square inches copper pad directly under the package, without occupying additional board space, can increase the maximum power from approximately 1.1 to 1.3W."
I am surprise that doubling the pad top and bottom doesn't yeald to better results!!!
Where would the heat from the bottom go? I believe I have seen someone do an smd pad with through holes/vias and pads on both sides. I can see how this might possibly increase cooling due to tunnel effect of the holes, but it is a guess.
yeah that's what I mean. It's unclear on the document where vias are, it almost look like they had bottom pad with no vias, but that wouldn't make any sense, so I am assuming the test had proper vias.
Either way if I can achieve 1.1W with only top pad I can use bottom for routing and I don't need more than 0.5W dissipation anyway and the 50% margin is what I uausally try to aim on my designs for reliability (wherever and whenever it's possible)
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