Sunday, August 31, 2014


MC34063 is buck boost type of the smps IC . This IC comes in DIP ,SOIC and some other packages and requires minimal circuit for making it work. With just a timing capacitor  and LC external filter.The buck boost is ready to juice up the circuit.
The MC34063A Series is a monolithic control circuit containing the primary functions required for DC−to−DC converters. These devices consist of an internal temperature compensated reference, comparator, controlled duty cycle oscillator with an active current limit circuit, driver and high current output switch. This series was specifically designed to be incorporated in Step−Down and Step−Up and Voltage−Inverting applications with a minimum number of external components.
Here's the link for the datasheet of the IC. The datasheet includes all the required schematics and values for the IC to operate.

Here's a circuit with external switch with 2n3055 as the external switch as its internal switch can only handle 1.5A of current and limits the current to only 1/2 of 1.5A ie 750mA according to datasheet. 
The following circuit can make it pass about 7 amp output current as 2n3055 output current is 15A. The feed back network will control the output voltage.
This is a online MC34063 calculator.

Here's the 3d of the circuit.


  1. Cant work at 7 amper , must change the R1 resistor...

  2. Yes...i think so , i just need the circuit for about 5 amp max in my application, so it worked well. May be for 7 amp r1 should be changed ......have to check the datasheet.