*** NE1 know why Power-One uses the LM723 pins 1,8 and

[rob1234]

seems like 14 on their open frame linear supplies.
The Data sheet shows NC for those pins.
I've heard that some enginers use NC pins to keep the chip at a certain temperature, but I'm sure that is not the reason here.
Anyone have a schematic for any power-one linear supplies ?
Thanks

 

[Optikon]

seems like 14 on their open frame linear supplies.
The Data sheet shows NC for those pins.
I've heard that some enginers use NC pins to keep the chip at a certain temperature, but I'm sure that is not the reason here.
Anyone have a schematic for any power-one linear supplies ?
Thanks

Why are you sure that is NOT the reason?

Being a linear regulator, you can probably assume it is for heatsinking purposes as those pins serve no function for the operation. They are likely tied to the ground plane.

And strictly speaking, this practice is not to keep the chip at a certain temperature (the environment, load & device geometries determine that) but rather to assist in heat transfer for more effective cooling. The only actual temperature on the part to stay below is the maximum junction temperature rating of the device. Also operating at lower temperatures offers better reliability.

 

[rob1234]

Its for sure not the reason here, if you have a power one lying around, look at those pins, it has a bypass cap, resistor, well you get the idea.
Do you have any idea what those pins on the lm723 could be used for other than what we have discussed? Pins 1,8 and 14.
Heat transfer lets say is one, there has to be other reason.
Thanks for your reply, I like sharing opinions and ideas.
Rob.

 

[Sebi]

NC mean: No internal Connection, only a pin on the package. Most of case irrelevant when You connect it to GND or V+.
Sometimes some manufacturers made connection with neighbor pin, without notice!
So i not recommend to use these pins.

 

[Optikon]

Its for sure not the reason here, if you have a power one lying around, look at those pins, it has a bypass cap, resistor, well you get the idea.
Do you have any idea what those pins on the lm723 could be used for other than what we have discussed? Pins 1,8 and 14.
Heat transfer lets say is one, there has to be other reason.
Thanks for your reply, I like sharing opinions and ideas.
Rob.

Ok if not for heat, here is another idea, it might be for a drop in replacement of another type of regulator in the same package. In the drop in part, these pins might be used for the function. This idea gives power one the option ot use two different parts possibly..I've seen it done before.

 

[rob1234]

Ok, now these are good reasons

Many thanks for opinions, they are good one.