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PSU5 LM323K Replacement

PSU5 LM323K Replacement

Weight: 0.0 lb
Regular price $8.95 USD
Regular price Sale price $8.95 USD
Sale Sold out

5V 3A switch-mode voltage regulator, high-efficiency replacement for the obsolete LM323K. 20V Maximum Input

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.

For pinball machines or application with large electrolytic capacitors preceding the LM323K consider using the PSU5_NN instead of this module.


  • Drop-in replacement of the obsolete LM323K and LM78H05K  or equivalent linear voltage regulator.
  • Guaranteed 3A continuous 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 dissipation with superior voltage regulation compared 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.
  • Sold with pins soldered in place.
  • 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.
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