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PSU5 LM323K Replacement

Availability: In stock

  • Buy 5 for $7.95 each and save 12%
  • Buy 10 for $6.95 each and save 23%
  • Buy 20 for $6.25 each and save 31%
PSU5 LM323K Replacement is available for purchase in increments of 1

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This is a 5V 3A switch-mode voltage regulator. It is a high-efficiency replacement for popular three-terminal LM323K linear regulators and it is pin-to-pin compatible with the common and now obsolete LM323K linear regulators. The mechanical design allows the PSU5 to fit anywhere where an LM323K was used. The bottom of the PCB is ground, just like the case of the LM323K. The maximum continuous output current is 3A and at room temperature the PSU5 does not need a heatsink to maintain this current indefinitely. All the required capacitors are included on the module, no external capacitors are required and additional input capacitors do no harm. The output voltage guaranteed to be within +/-1% as the load varies. The module has a (tiny) trim potentiometer and the voltage is factory adjusted to within 50mV of 5V with a 12V input and a 1A load. The original LM323K had a rather loosely specified output voltage and it could vary by as much as 250mV without load and at room temperature. Many designs incorporated some circuitry to raise the output voltage to prevent under voltage resets of microprocessors. The PSU5 LM323K replacement design can be adjusted by up to 500mV in either direction with the trim pot to ensure compatibility with almost all circuits that used the LM323K. The module has thermal shutdown and current limit protection. The absolute maximum input voltage is 20V. The PSU5 can be mounted on existing heatsinks, even ones that use sockets under the heatsink. The hole diameters and pin diameter is exactly the same as the original package dimensions.


  • Drop-in replacement of the obsolete LM323K or equivalent linear voltage regulator.
  • Guaranteed 3A output current.
  • Identical input voltage range of 7.2V to 20V
  • Suitable for use in Pinball machines and video game consoles
  • High efficiency switching regulator design reduces power disspation with superior voltage regulation compare to the LM323K.
  • Thermal shutdown and current limit protection
  • Board dimensions are identical to the TO3 package of the LM323K.
  • Heatsinks are optional.
  • All components are mounted on one side of the PCB
  • Highest component is the inductor at 5mm above the PCB.
  • Available with or without pins.
  • Gold plated pins and PCB to withstand harsh environments over the long term.
  • Can drive inductive loads such as solenoids and DC motors.
  • 500kHz Switching Frequency
  • Made in the USA
  • The photographs show an LM323K next to the PSU5 module for a size comparison.
  1. Works great for pinballs Review by Pierre

    Installed several of these on pinball machines, especially on WPC89 power driver boards. Works exactly as expected, with a word of warning though : it's necessary to use metal screws and nuts to maintain continuity between component and solder side. The first time I installed one of these, it didn't work at all, because the small washer under the factory nut was shorting with a small SMD resistor - at least short circuit protection works. So I reajusted the nut and it worked absolutely fine.

    For my second try, I decided to use plastic nuts to avoid shorting the resistor. I only had 1,40 V on the +5V test point. I took the board apart only to realise continuity was missing for the "casing" of the regulator.

    So : for pinball machines, use the factory METAL screws + washer AND make sure the nut isn't shorting the SMD resistor the closest to the mounting hole. (Posted on 4/5/18)

  2. Great Product Review by Pintech

    I've used over a Dozen of these now with NO problems. Adjustable voltage is a plus and it runs very cool. (Posted on 3/28/17)

  3. Wow!! Review by Alain

    Finally solved my reset problem on the Williams pinball have been working on. I changed 4 times the LM323K with new ones, with the exact same result, the voltage kept falling down to 4.78v after a few minutes. I install the PSU5 and wow! what a change. The voltage never drop below 5.00v.
    For now on I only buy the PSU5 instead of the original LM323K and will tell all my friends about your products.

    Thank you (Posted on 6/9/16)

  4. Where's the Beef? Review by Ralph

    I can't find a data sheet to provide full info on using this module. At least it would be useful to provide a part number for the chip used. I can see the board is bigger than the TO-3 package it replaces. I would need to have full mechanical details before I could use this device.

    I give this device a C- until they provide a data sheet. (Posted on 10/3/15)

  5. Lovely device! Review by th_in_gs

    I bought one of these not to replace a LM323K, but to use in a new project.

    I couldn't be happier. It's very easy to interface with, and runs very cool, even with a 2A draw. It's small, and looks very neat too, which I always like.

    Would definitely recommend. (Posted on 8/1/14)

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