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LM334: Achieving higher currents than the LM334 supports

Intellectual 310 points

Replies: 8

Views: 228

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 ATL431LI for improved system performance in a p2p package or a ultra  small X2SON (1mm x 1mm x 0.4mm)

    Check out: Voltage Reference Design Tips For Data Converters a new app note that discusses voltage reference error and how it affects ADCs/DACs

  • 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 ATL431LI for improved system performance in a p2p package or a ultra  small X2SON (1mm x 1mm x 0.4mm)

    Check out: Voltage Reference Design Tips For Data Converters a new app note that discusses voltage reference error and how it affects ADCs/DACs

  • 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 ATL431LI for improved system performance in a p2p package or a ultra  small X2SON (1mm x 1mm x 0.4mm)

    Check out: Voltage Reference Design Tips For Data Converters a new app note that discusses voltage reference error and how it affects ADCs/DACs

  • In reply to Marcoo Z:

    Hi Marcoo,

    Thank you for your reply. That sounds great :)

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