for cost reasons, current carrying capacity is often boosted by using a pass transistor ('2905, '3055) around the regulator instead of paralleling devices. you can parallel the devices, however -- it's just a few centimes more expensive.
If you decide to parallel these regulators, place a small resistor (0.1 or 0.22 ohm) in series with each output. This will make them happier in sharing the current.
National Semi's product folder on the LM317 shows how to boost current capacity -- they use a super-matched pair of transistors (because it was a device they manufactured) -- you can use MJE2955, 3055.
If you decide to parallel these regulators, place a small resistor (0.1 or 0.22 ohm) in series with each output. This will make them happier in sharing the current.
National Semi's product folder on the LM317 shows how to boost current capacity -- they use a super-matched pair of transistors (because it was a device they manufactured) -- you can use MJE2955, 3055.
Hi,
for the positive supply you can replace 3 LM317 by one LM338T or K.
The T-version comes in a TO220-case and K means TO3.
The negative branch will become more difficult, because there are afaik no regulators of more than 3 A.
In the LM317 and LM337 datasheet (NatSemi) are applications with paralleled devices to increase their current capability.
Onra
for the positive supply you can replace 3 LM317 by one LM338T or K.
The T-version comes in a TO220-case and K means TO3.
The negative branch will become more difficult, because there are afaik no regulators of more than 3 A.
In the LM317 and LM337 datasheet (NatSemi) are applications with paralleled devices to increase their current capability.
Onra
jackinnj said:
this is the way I would prefer, too
for the positive LM317 you use a PNP TO3 transistor
for the negative LM337 you use a NPN TO3 transistor
Here is link to such a project with description:
LM317T Voltage Regulator with Pass Transistor
An externally hosted image should be here but it was not working when we last tested it.
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