Voltage regulator chip stacking

[calin666]

Good morning everyone.
I have a project that I am working on thqt is pretty simple, and had a question about.
I have built a variable voltage regulator, using an NCP630A 3amp voltage regulator, with an input of 7.4 volts, and it works great.
However, I want to have a higher amp draw capability. Is it possible to stack that chip (like stacking FETs)? As in, stack two chips, and have a 6 amp draw capability?

 

[Harald Kapp]

Although this is possible, I don't recommend it. The chips have tolerances and you will need additional circuitry to balance the load.
There is another inexpensive trick using an external transistor and a few resistors. This should work with the NCP630A, too.

See also this thread.

Harald

 

[calin666]

Nice.
Usage for this is not going to be constant (maximum 15 second on, and that is rare, with an off for maybe 30 seconds, and so on).
I already use a heat sink as is. In addition to that I am already working with a pre printed board, and need to stay with it, and the size, etc.
I am working with this: http://www.madvapes.com/variable-voltage-regulator-board-kit-rev-3.html
If I do, end up just stacking, do you really think it would be that much of a problem?

 

[Harald Kapp]

If you insist, you can always try. But load balancing (or current balancing, for that) is required to ensure even distribution of the loads. Otherwise the chip with the highest output voltage (remember: tolerances) will be forced to deliver the max. current. Only when this chip starts dropping the output voltage due to current limiting will the other chip(s) start delivering noticeable current.

There are two disadvantages:
- uneven distribution of the load can lead to early demise of the chips with the highest share of the load
- regulation of the output voltage can be bad.