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Original question:

TINA/Spice/LM340: LM340 and LM320

LM340: LM340T-12

wessel kooiman
Prodigy 30 points
Part Number: LM340
Other Parts Discussed in Thread: LM1085

i am searching for a lm340T-12 lt spice model, but cant find it on the site

Is this model available anywhere? 

  • 0
    TI__Mastermind 32600 points

    Hi Wessel,

    This LDO was made years before our spice model development efforts were initiated. As such, we do not have a model for this device.  All of our modern devices come with spice models available online.  If you can give me your requirements I can help recommend a more modern device if you would like.

    Thanks,

    Stephen

  • 0 in reply to Stephen Ziel
    Prodigy 30 points

    Hi Wessel,

    Thank you for your response. I'm planning to construct a linear power supply and require a suitable voltage regulator for the task.

    The desired output voltage is 12V, and I need a total power output of at least 20W, equivalent to 1.7A. I understand that 20W is relatively highfor a linear power supply, but I prefer to avoid a switching one.

    In most instances, the load will be well below 20W, but in some cases i need to controll a high power motor so the power must be there (power loss is no real problem).

    Thanks,
    Stefan

  • 0 in reply to wessel kooiman
    TI__Mastermind 32600 points

    Hi Stefan,

    What is your input voltage? 

    Thanks,

    Stephen

  • 0 in reply to Stephen Ziel
    Prodigy 30 points

    the input voltage of the power supply will be 230Vac and there is no transformer determined yet. 

    So there is still a lot of  freedom in the Dc input voltage

  • +1 in reply to wessel kooiman
    TI__Mastermind 32600 points

    Hi Wessel,

    20W load is not an issue for an LDO, it is the power dissipation across the LDO that makes a difference.  Can you use the LM1085? It comes in a fixed 12V option and is capable of 3A loading.  The dropout is 1.3V (typical) or 1.5V (maximum) at 3A. So if you can support around 14V on the input, you will have 2V of headroom (to account for tolerances on Vin and Vout).  Then you only have 3.4W dissipation across the LDO during those brief moments where 1.7A is needed to power the load.  The TO-220 package has low thermal impedance according to the JEDEC standard but if you really needed to, you could add a heat sink (but if the 1.7A peak load is brief and with a low duty cycle, this is probably not needed).

    Thanks,

    Stephen

  • 0 in reply to Stephen Ziel
    Prodigy 30 points

    Thanks a lot!
    But there is also no ltspice model for this? i can only find the pspice wich i can convert to ltspice.

    the broblem i have with this model is that it has 4 pin in stead of 3, and there is no real clear pinout 


  • 0 in reply to wessel kooiman
    TI__Mastermind 32600 points

    Hi Wessel,

    Due to the LTSpice license agreement, we are legally unable to assist with LTSpice questions.  We are unable to publish LTSpice models onto TI.com due to the license agreement for that software.  You can try taking the PSpice model published on TI.com and import it into LTSpice or any Spice simulator, or you can use PSpice for TI.

    Thanks,

    Stephen