Built a DC-DC boost converter 12-22v based on LM2577-adj. Seems to burn-out after three
startups from 12V Battery. Ideas?
startups from 12V Battery. Ideas?
DC-DC boost converter burning out LM2577-adj - detective work needed.$?
- Thread starter Katecooper
- Start date
It looks good to me.
Is the current rating high enough on the inductor.
If you apply 12 volts to the input and adjust the potentiometer to 0 ohms then the 12 volts (minus a diode drop) will be applied to the FB pin.
I can't find a voltage limit for the FB pin in the data sheet but for other regulators it is only a few volts. Put a resistor in series with the pot so that only a couple of volts go to the FB pin when 22 volts is on the output and the pot is adjusted to 0 ohms.
Also, if you adjust the pot to 50 K ohms the switcher will try to output over 60 volts. This is very near the maximum the part allows. You need to increase the 1K ohm resistor to give a lower output voltage when the pot is set to 50K.
My wild guess is you can use about 5 k Ohms for the resistor from FB to ground and about 47K in series with the pot. Make sure you verify these values before trying them because they could easily be wrong.
I can't find a voltage limit for the FB pin in the data sheet but for other regulators it is only a few volts. Put a resistor in series with the pot so that only a couple of volts go to the FB pin when 22 volts is on the output and the pot is adjusted to 0 ohms.
Also, if you adjust the pot to 50 K ohms the switcher will try to output over 60 volts. This is very near the maximum the part allows. You need to increase the 1K ohm resistor to give a lower output voltage when the pot is set to 50K.
My wild guess is you can use about 5 k Ohms for the resistor from FB to ground and about 47K in series with the pot. Make sure you verify these values before trying them because they could easily be wrong.
And what is the minimum output current needed?
