34063 used for DC-DC supply convert circuit

Published:2011/12/1 20:17:00 Author:May | Keyword: DC-DC supply convert | From:SeekIC

34063 is a kind of intergrated circuit which is used for DC-DC power supply converter.It canbeused for voltage boost, step-down and polarity reversed. The highest polarity reversed effect is 90%, the highest step-down effect is 80%, conversion efficiency and work frequency filter capacitorare indirect proportion. Moreover, when output power can not reach therequired value, for example, when >250~300MA, it can enlarge current through the method of external expansion power tube, andambipolar or MOS expansion current tube is ok.The peripheral cell nominal meaning and their value computing formula:Vout (output value)=1.25V(1+R1/R2)Ct (timing capacitor):decide internal operating frequency. Ct=0.000004*Ton (work frequency)Ipk=2*Iomx*T/offRsc (current-limiting resistance):decide output current. Rsc=0.33/IpkLmin(inductance): Lmin=(Vimin-Vces)*Ton/IpkCo ( filter capacitor): decide output voltage ripple factor, Co=Io*ton/Vp-p(ripple factor)fixed value parameter:Vces=1.0V ton/toff=(Vo+Vf-Vimin)/(Vimin-Vces) Vimin: minimum value when input voltage unsteadinessVf=1.2V high-speed switch diode forward voltage drop



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