why does a type opamp have so many different types of packages/pins?

Hi Hai,

many customers always wish the smallest package to save board space. With every step of inovation the package becomes smaller and smaller. But there are still the older boards which have the OPAmps in a bigger package. As board layout making is very expensive and time consuming, many consomuers need to get the older parts in the bigger packages. That's why a whole spectrum of packages is offered at the same time ranging from DIP8 to PWSON.

The package also has an effect on solderability. The smaller the package the harder to solder. The PWSON package even needs a pad at the bottom side of package to be soldered onto the board for meachnical reasons. This is realy hard to accomplish by hand soldering.

The package also has an effect on the thermal properties. The "junction to ambient thermal resistance" hugely differs from package to package. So when you plan an application where the OPAmp has to dissipate lots of heat, you should have an eye on this topic.

And when it comes to high speed OPAmps, finally, the smallest package should be preferred. But even here the thermal properties of package can play a role, if the OPAmp has to dissipate lots of heat.

For any other application the package size doesn't play a relevant role usually. But it can make a difference in board space whether you take single, dual or quad OPAmps. I personally prefer dual OPAmps in the most cases because they offer an optimal compromise and allow a space saving routing of the feedback path circuitry and supply decoupling. Quad OPAmps, on the hand, can often result in a "swollen" layout when it's difficult to come close to the pins of package because of very many feedback components.

Kai