34063 Circuit for DC-DC Power Conversion

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MC34063A
34063 is a DC-DC power conversion integrated circuit, which is widely used and widely available at low cost. It can be used for voltage up, down and polarity reversal. The polarity inversion efficiency is 65%, the boost efficiency is 90%, the boost efficiency is 80%, and the conversion efficiency is proportional to the working frequency filter capacitance. In addition, when the output power can not meet the requirements, such as > 250~300MA, the current can be enlarged by means of an external power amplifier tube, bipolar or MOS type diffuserYes.
Nominal meaning of peripheral elements and the formula for calculating their values:

Vout = 1.25V (1+R1/R2)

Ct (timer capacitance): determines the internal operating frequency. Ct=0.000 004*Ton (operating frequency)

Ipk=2*Iomax*T/toff

Rsc (current limiting resistance): Determines the output current. Rsc=0.33/Ipk

Lmin (inductance):Lmin=(Vimin-Vces)*Ton/Ipk

Co (filter capacitance): determines the ripple factor of the output voltage, Co=Io*ton/Vp-p (ripple factor)

Fixed value parameters:

Vces=1.0V. ton/toff=(Vo+Vf-Vimin)/(Vimin-Vces) Vimin: Minimum value when input voltage is unstable

Vf=1.2V Fast Switching Diode Forward Voltage Drop


Other manual parameters:

Parameter name symbol unit MC34063CW34063 IRM03A
Input voltage Vin V 2.5~40V 2.5~40V 2.5~40V 2.5~40V
Output voltage Vout V 1.25~40V 1.25~40V 1.25~40V 1.25~40V
Output current Iomax A 1.5A 1.5A 1.8A
Operating frequency f kHz 0.1~100KHZ 0.1~100KHZ 0.1~100KHZ 0.1~100KHZ
Power P W 1.25W 1.25W 0.9W
Working temperature Ta 0~70 degrees 0~70 degrees 0~70 degrees



Attentions in practical applications:

1: Fast switch diode IN4148 can be used, IN5819 must be used in high efficiency situations!

The voltage that 2:34063 can withstand, that is, the sum of input and output voltage cannot exceed 40V, otherwise it cannot work safely and steadily.