[SOLVED] [URGENT] Boost Converter voltage drop.

[amayilsamy]

I design Boost converter using MC34063A.

Input Voltage= 5 V to 12 V. Output = 35 V @ 20mA

Load Resistance= 2.2 KOhm.

While I Connect a load in output that time Output voltage automatically reduced at 18 V.

View attachment Circuit 2_bot.bmp

View attachment Circuit 2_top.bmp

 

[tpetar]

What parts did you use. What coil and with what current rating you use?

You didnt show values of resistors in circuit. Probably you have problems in circuit parts values.

Post photo of your PCB with parts, and complete circuit with parts values what you have.

 

[amayilsamy]

I'm using 170uH Toroidal Type Coil that is locally made.

And other values As the same in the Schematic.

 

[tpetar]

From picture I'm not sure that inductor have 170uH.


Check this calculator for circuit values:

MC 34063 Step-Up/Down Calculator
**broken link removed**

I'm using 170uH Toroidal Type Coil that is locally made.

And other values As the same in the Schematic.

View attachment 91974

View attachment 91973

I didnt saw R1 and R values in schematic document ? These values set you output voltage.


;-)

 

[amayilsamy]

Resister R1 Value is = 1 K. R2 100 K pot

 

[amayilsamy]

There was problem in Inductor Coil . Now I changed the Coil Its working good.

 

[tpetar]

I'm glad to see that this works. Now check maximum output current.

:wink:

 

[amayilsamy]

Now working in 78% efficiency . And the maximum 30 mA. :smile:

 

[tpetar]

Its ok for MC34063.