LM1117 Output Voltage adjustment

[vaibhavpawar]

Hi... I am newbie to Power Supply design.

I am using LM1117 - 5 Volt ( LM1117MPX-5.0 ) Texas IC in my application. Datasheet is saying dropout voltage is 1.2V.
Is it means we have to apply 5V+1.2V = 6.2V at input pin to get 5V. And if above is true, then if I apply 12 V, then considering dropout voltage I will get 12-1.2=10.8V at output.?

If it is true, then operating input voltage is suggesting 15V.

Pls suggest If we apply 15 V at input, then what voltage we will get if we use LM1117-5V. Is it 5V fixed or (15-1.2=13.8V).

Thanks in advance.

 

[ud23]

lm117 5 voltage will give you output 5v -DOvoltage for given input from 7v to mentioned max input voltage.so if supply is 12 or 15 v output is around 4.8 v.

 

[schmitt trigger]

A voltage regulator is precisely that...a regulator!

It will maintain a constant output voltage all the way from its maximum input to the dropout voltage; and from its minimum to its maximum load.....with proper heatsinking, of course.