IC heat disipation calculations

get a handle on the heat disipation calc's becuase I suspect it is over heating and shutting down.

Some chip makers (National, Texas, Linear) have good downloadable app notes on heat sinking.

D from BC

get a handle on the heat disipation calc's becuase I suspect it is over heating and shutting down.

How hot does the top of the package get? Does freeze spray fix the shutdown?

Glue a heatsink to the package and see if that helps.

What's your output current?

What is "Bucket design"?

John

ying to get a handle on the heat disipation calc's becuase I suspect it i= s over heating and shutting down.

P3063PG

I don't understand the question. The package has a 180=20 degree C temperature rise above ambient for each watt it=20 dissipates. Board layout can alter this a bit, since the=20 copper traces are the main path for heat to escape the chip.

By Bucket design, I assume you mean buck converter.

What output current is this chip supplying?

Is the chip being heated by proximity to the output diode?

get a handle on the heat disipation calc's becuase I suspect it is over heating and shutting down.

Something along the lines of:

Pd~= (Vin * Icc) + (VSWCE(DROP) * Iswitch(avg) * ton/(ton + toff))

Should come close (although it ignores losses during the darlington switching, so actual losses are going to be higher). VSWCE(DROP) is 1.3V max., 1.0V typical. Icc is 7mA max.

The SOIC package is not very good for power dissipation.

Best regards, Spehro Pefhany