• Resolved

LM2587 typical boost regulator application


Recently I bought several LM2587-ADJ/NOPB, and now I meet some problems with application provided by datasheet.

Input 6V, 1A, DC source. The output side we connect 100ohms power resistor.

Actually, the circuit behaves well with no load, the output voltage is exactly like what we set 12V. However, as 100ohms resistor connect to the output side, the output voltage drop significantly, like 6-8V, and sometimes the chip gets hot and burns out.

Ask for help! How to set the output voltage when we get a load.

  • In reply to Marc Davis-Marsh:

    for the load 330R (the current is 106mA), the circuit is working fine. Switch ON and OFF, no problem. Please check the waveform.

  • In reply to Zhongwen Jin:

    For the issue of turning on with the load.  I think the combination of your large output capacitor and the 51ohm load is causing your input supply to crash during startup.

    Your input supply has to charge up both the input caps, output caps and load  during start up, and if it doesn't finish ramping up before the part starts switching and drawing even more current it can collapse.

    Try reducing your output capacitor from 1200uF to 220uF or 330uF.

    Try this and then we can see if we can optimise your performance.


  • In reply to Marc Davis-Marsh:

    I have tried 470uF and 110ohms at the output end. But the circuit fails to turn ON with this load.

    I am not sure where is wrong in my circuit. Basically I am doing a circuit in the datasheet. Please see the picture below. It says 36V @ 2A. Rightnow, i can only get 212mA working while using a 165ohms load.