Boosted Circuit Based on MC34063

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asa1995's picture
Boosted Circuit Based on MC34063


I’m a novice,and I want to ask for some advice about the boosted circuit based of MC34063A. ( the datasheet of MC34063A

The inputted voltage is 5V when the output is 30V, current is 70mA and the oscillation frequency is 33K.

The diode I chose is IN5819(SS14)

timing capacitor /Ct=1047 pF

peak current Ipk=1029 mA

current-limiting resistance /Rsc=0.292ohm

electrical inductance /Lmin=102 uH

filter capacitor /Co=33 uF

R=180 Ohm

R1=2.7k R2=62k (29.95V)

I don’t know why the texting output voltage is more than 29V after I built the circuit. But quickly the voltage will be pull down. As a matter of fact,the current is just about 10mA. And the MC34063 was so hot.

Could anyone help me out? Thanks a lot.