TL783C voltage regulator confusion

[mkruger]

I'm looking at the TL783 voltage regulator from the top view. These are popular in 48v phantom power supplies.

The .PDF datasheet specifies that the right leg is IN, the middle is OUT, and the left is ADJUSTMENT. But the block diagrams in that same data sheet makes is seem like the adjustment is the middle leg, which would make this a lot easier to work with and compatible with my circuit board....

PDF: http://www.teadora.com/tl783vr.pdf

so does anyone know the proper leg assignment?

-mike

 

[PRR]

> datasheet specifies that the right leg is IN, the middle is OUT, and the left is ADJUSTMENT. But the block diagrams in that same data sheet makes is seem like the adjustment is the middle leg,

Block Diagrams are conceptual, NOT physical.

The block diagram is made to read easily.

The chip has to obey certain physical facts. The back of the die on a power device has to bond to the tab. With few exceptions, in an IC the back of the die is also the most negative pin in the IC. Yes, in the 783 the Adj pin is most negative but it is very low-current and they can float it down the 1.2V. And the standard lead-frame for TO220 has the tab connected to the center pin (for thermal balance, but really for historical reasons to do with the TO3 package).

Trust the picture on the first or last page of the datasheet. That's the physical reality.

Sorry, the center pin is the OUT. If your board disagrees, bend the pins UP and use insulated jumpers to bring them around to the right holes.

 

[mkruger]

thanks. i just wanted to make sure that there where no typos in the datasheet. this sucks, thime to make yet another board...

 

[PRR]

> i just wanted to make sure that there where no typos in the datasheet. this sucks, thime to make yet another board...

You should check the websites of several makers. TI.com had a newer version of that sheet. They have added some smaller surface-mount packages. but the TO220 is still pinned the same. Dig and you might find a second opinion from a second-source factory, but I bet it is the same pinout. TO220s are like that. (It is also why 78xx and 79xx have different pinouts: different most-negative power pin.)

> time to make yet another board...

If you are stuffing it yourself, just jumper it. Works fine.

If you are boarding for someone else to stuff, back to the FeCl.....