hi every body
iam trying to designed a 12-120 Dc-DC converter with 300mA output but it has voltage drop.
is there any body can help me?

 

Is the inductor 47uH? It is difficult to read the diagram.
What is the current rating of the inductor?

I cleaned up the diagram a bit:

 

It wont work, pin 4 should be connected to ground, and don't see the point of using pins 15,16 unless your sensing overcurrent..
Also your reference voltage on pin 2 is set at 1V, yet your sensing half of that on the output side so that will shutdown at 0.5V.

Recommend you make the 56K on pin 2 a 22K preset, make the two 1K resistors across the output 470k to positive and 10K to negative , this will give you an output voltage of 120V with the preset set at 14K.

 

thanks every body that help me to solved my problem. now my circuits dont have ane voltage droped but Another big problem has been arisen and it is mosfet burning. i will just send apart of my circuita (my mosfet gaite drive). i hope that the new picture bee clear..