heating up of the MC34063AP IC

hi, am so greatful for whatever your doing cause its wonderful. well i was trying to come up with a charge regulator for a 12V,7Ahr sealed lead acid battery. i used the mc34063 IC as a step-down together with its associated electronic components as in the systematic lay out in the step-down configuration.

i supplied the regulator with 20VDC and i wanted 14.7VDC out and a current of 0.8A.

it regulated the voltage very well and i think the current too.

however it heat up in 1.5munites just after i had connected the battery on it; and the temperature shot to 210 o F in 4 minutes.

As the temperature goes high, the current from the power supply decreases and the current to the battery also decreases.
i tried cooling the IC by attaching a heat sink on to it but still the temperature shot up to 230 o F. i beg for any solutions and advice on what to do.

 

hi harald. thanks for the respond. am greatful. well the schematic is simillar to the one the link below though at co i used 100uF, the inductor is 15uH, R1=1.2K, R2=13.2K and Rsc=.o15

 

well, thanks so much KrisBluesNZ for the advise, that good information but can you do me a favour and send me a list of some of the switching regulators you recommend me to use and can be better for my exercise. thank you very much.

 

oh really, am sorry well the schematic is . and please can you give me advise on which will be the best components for the circuit. i have just began this and i would like to learn more, if possible you can send me a pdf where i can read. i just used a drawing of this schematic to construct this circuit. otherwise thank you so much for your advise.

 

thanks for the reply,
well i used the 15uH cause its what i had and i thought trying it out just to see if it could work. for CT i still used the 470pF.

just to ask you, could you give me any directions on how i can cool an inductor. the reason as to why am asking you such a favour is where i am in Uganda its really difficult to find electronic components, the suppliers here only have a few of them. i really would like to learn more of practical electronics but am limited by the fact that i have to make orders to outside manufacturers to import most of the components. here i beg you if you could recommend me to good suppliers of good electronic components cause feck products are too much this side.

thanks for all you am really great full for your time

 

cool steve, thanks for the advise, how ever still my problem stands that i can afford getting the right inductors in ma country. in most cases i have to order from out (importing) but i really find it hard getting the right supplier.


I like that idea of making ma own inductor though i have no idea on what to do . i beg if you could give me some crue on how to cool them that would be cool. you can even send may be a pdf to ma email address ([email protected]) i will be great full.

thank you.