Need 5 amp linear regulator spice model

Thread Starter

ElectricSpidey

Joined Dec 2, 2017
2,879
Hello...

I know this is a shot in the dark, but I would like to get my hands on a spice model for a 5 amp linear voltage regulator, either of the following will do.

LM138K

LM338K

I’ll even take the non “K” version.

Don’t need the symbol, I can probably swing that…just the .sub or .lib file. (but I’ll take both…)

I know one of these comes with PSpice but there doesn’t seem to be any in the wild.
 

eetech00

Joined Jun 8, 2013
4,037
Hello...

I know this is a shot in the dark, but I would like to get my hands on a spice model for a 5 amp linear voltage regulator, either of the following will do.

LM138K

LM338K

I’ll even take the non “K” version.

Don’t need the symbol, I can probably swing that…just the .sub or .lib file. (but I’ll take both…)

I know one of these comes with PSpice but there doesn’t seem to be any in the wild.
Hi

I have one for LTspice.

eT
 

Aadrik

Joined Dec 15, 2014
8
eetech00,
I don't see any .sub file in the zip. I see a text file but I am not sure what to do with it. I am new to LTSpice so I'm sorry if this seems like a simple question.
 

Audioguru again

Joined Oct 21, 2019
6,776
Why do you need to simulate a voltage regulator? Use a battery instead. In a simulation both do the same things.
The simulation of the voltage regulator might show it limiting the maximum current. Is that what you want?
 

Aadrik

Joined Dec 15, 2014
8
Why do you need to simulate a voltage regulator? Use a battery instead. In a simulation both do the same things.
The simulation of the voltage regulator might show it limiting the maximum current. Is that what you want?
I am testing a schematic I was given and the values that they put are not quite lining up with what I am getting when I am doing the math myself. I wanted to simulate the circuit to see if maybe I was just doing in wrong.
 

Audioguru again

Joined Oct 21, 2019
6,776
I am testing a schematic I was given and the values that they put are not quite lining up with what I am getting when I am doing the math myself. I wanted to simulate the circuit to see if maybe I was just doing in wrong.
You did not post the schematic and resistor values that are producing trouble. The resistors for an LM338 are the same as for an LM317.
The datasheet for the LM338 clearly shows 120 ohms and also shows the voltage across it. Ohm's Law tells you the current in both resistors and adding the voltages gives the output voltage. Simple.
 

Aadrik

Joined Dec 15, 2014
8
You did not post the schematic and resistor values that are producing trouble. The resistors for an LM338 are the same as for an LM317.
The datasheet for the LM338 clearly shows 120 ohms and also shows the voltage across it. Ohm's Law tells you the current in both resistors and adding the voltages gives the output voltage. Simple.
My math checks out. The values that they put on this schematic are not correct. I can get the voltage they are saying but not the current, or, I can get the current and not the voltage. Not sure where they came up with this values. Unfortunately I can not post the schematic. Thanks for the help though.
 

Audioguru again

Joined Oct 21, 2019
6,776
The datasheet clearly shows that its maximum output current depends on the voltage from its input to its output:
With 10V, it produces at least 5A, typically 8A continuously, or typically 12A for 0.5ms.
With 30V, it produces 1A maximum and less current at 35V.
 
Also consider the (obsolete) Linear Tech LT338A, as an improved LM338K although the datasheet shows the same for output current. There might be LT Spice models for it. At this power level, people use a buck-converter to get away from the heat.
LT338A current limit.JPG
 
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