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LM334: Achieving higher currents than the LM334 supports

Prodigy 250 points

Replies: 8

Views: 162

Part Number: LM334

Could someone recommend a good component that achieves a constant current of 50mA (so ideally a higher maximum output current not to run it at maximum load).

The LM334 has a limit of around 10mA, and I couldn't find more components on Texas Instruments that support higher currents...

  • Hi Luke,

    Are you looking for a current source or current sink?

    IF you are looking for a current source, our best way is to use a LM4041-N ADJ and a FET to make a current source.

    I would use a TL431 and a FET to make a current sink.

    Both of these solutions are a bit bigger but they can provide you with a high current alternative to the precision LM334.

    -Marcoo

     

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    If you feel your thread is resolved, please selected Answered.

    If you are using the TL431, check out the new TL431LI and its low Iq counterpart ATL431LI for improved system performance in a p2p package.

    Check out: Designing with the improved TL431LI for how to calculate worst case error on all '431 devices.

    Check out: Designing with the ATL431LI in Flyback Converters for tips and tricks on how to lower standby Iq to meet DoE and CoC regulations.

  • In reply to Marcoo Z:

    I need a current source, so I will check out the LM4041! ONLINE i have also found an LM317 being used as a current source, would you suggest that? It seems to be a similar concept to what you suggested.

  • In reply to Luke Galea:

    Hi Luke,

    The LM317 does work as a current source. Nice find, we have such a large portfolio it can be difficult to find devices.

    Both solutions work. The LM4041-N adj will provide a more accurate current over temperature but if you don't need the high precision then the LM317 will work.

    -Marcoo

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    If you feel your thread is resolved, please selected Answered.

    If you are using the TL431, check out the new TL431LI and its low Iq counterpart ATL431LI for improved system performance in a p2p package.

    Check out: Designing with the improved TL431LI for how to calculate worst case error on all '431 devices.

    Check out: Designing with the ATL431LI in Flyback Converters for tips and tricks on how to lower standby Iq to meet DoE and CoC regulations.

  • In reply to Marcoo Z:

    Cheers! That's why I use these forums since people having experience can guide me better :) I'll have a look at the accuracy of the LM314 and see if it's enough.

  • In reply to Luke Galea:

    Could somebody kindly explain the purpose of the 2N2905 and 2N3964 please? And whether a 12V supply can be used instead of 15V?

    Thanks!

  • In reply to Luke Galea:

    Could somebody kindly explain the purpose of the 2N2905 and 2N3964 please? And whether a 12V supply can be used instead of 15V?

    Thanks!

  • In reply to Luke Galea:

    Hi Luke,

    These PNP are in a darling ton configuration for higher current gain. The LM4041-N can only source up to 12mA and thus this limits the maximum current through the 2N2905. With the 2N3964, the 12mA is current boosted with this additional stage which allows a higher maximum current source.

    -Marcoo

    ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

    If you feel your thread is resolved, please selected Answered.

    If you are using the TL431, check out the new TL431LI and its low Iq counterpart ATL431LI for improved system performance in a p2p package.

    Check out: Designing with the improved TL431LI for how to calculate worst case error on all '431 devices.

    Check out: Designing with the ATL431LI in Flyback Converters for tips and tricks on how to lower standby Iq to meet DoE and CoC regulations.

  • In reply to Marcoo Z:

    Hi Marcoo,

    Thank you for your reply. That sounds great :)