Noob Q - LM337 SOIC: four Vin's?

[DaveC]

What is the purpose of having 4 pins assigned to Vin? Layout convenience?

http://www.ti.com/lit/ds/symlink/lm337l.pdf

Thanks.

 

[Phil Hobbs]

What is the purpose of having 4 pins assigned
to Vin? Layout convenience?

Heat sinking. You usually need a fairly big copper pour.

Cheers

Phil Hobbs

 

[Tim Wescott]

On Fri, 08 Apr 2016 09:15:19 -0700, DaveC wrote:

What is the purpose of having 4 pins assigned to Vin? Layout
convenience?

http://www.ti.com/lit/ds/symlink/lm337l.pdf

Thanks.

What Phil said -- the input of that chip is connected to the collector of
the output transistor, which is where most of the heat is generated. In
that package, the way you get heat out is through lots of pins.

This is a big driver for different linear regulators having different
pinouts -- because depending on the regulator layout, the heat-
dissipating portion of the circuit will be connected to different pins,
and the manufacturer wants to provide you a way to get that heat out.

--

Tim Wescott
Wescott Design Services
http://www.wescottdesign.com