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LM62460-Q1: Delivering 5A to varying load

Christoph Amann1
Prodigy 10 points
Part Number: LM62460-Q1
Other Parts Discussed in Thread: LM338

Hello everyone,

i have to deliver 5A to a varying load (between 1 ohm to 6 ohm) for about 1.2 seconds. My supply voltage is about 30V. On my first test circuit i used the LM338 voltage regulator and set it up as a current limiter like in the following figure:

The device works as intended and is limiting at 5A regardless of the load. The problem i have is that the device gets too hot on smaller loads so the thermal shutdown appears after about 100 ms depending on load. I need to provide it for atleast 1.2 seconds. And we dont have much space for a heat sink.

Now i was thinking about using an adjustable DC/DC stepdown converter or something similar. The idea is to adjust the output voltage to the amount i need for the 5A. I already looked through some step down converters but i only found ones where the output voltage is set by feedback with voltage divider on the output. Is there a device where i can set the output voltage via output-current like in the figure above with the LM338? Thanks :)

Best regards

Christoph

  • 0
    TI__Mastermind 47060 points

    Hi Christoph,

    As you mentioned, most of the step down converters are set to provide a fixed output voltage based on the feedback and internal compensation network. 

    I don't think there is anything in the DC/DC step down portfolio that can work in your application where you want output voltage to be set solely by a variable output current load.  

    You may want to start a new thread with the LM338 such that an apps engineer in the LDO team can help support your application. Perhaps they might have a new alternative device that works as intended but stays less hot.

    Regards,

    Jimmy