Dropout voltage Buck Converter?

[jeff77789]

What is the dropout voltage for a LM2596 DC to DC buck converter?

for 5v 7805 voltage regulators i know that the output voltage drops around 6-7v depending on the regulator

but what about buck converters? does it work in the same way? does it even have a "dropout voltage?"


thanks!

 

[tpetar]

What is the dropout voltage for a LM2596 DC to DC buck converter?

for 5v 7805 voltage regulators i know that the output voltage drops around 6-7v depending on the regulator

but what about buck converters? does it work in the same way? does it even have a "dropout voltage?"


thanks!

You can see in datasheet this data for particulat part separately. For 7805 minimal voltage drop is 2,5V-3V. If input voltage is 20V and output is 5V (for 7805) voltage drop is 15V.

In other hands, there is LDO - low drop voltage regulators which can have minimal voltage drop starting from 0,2V to 0,5V.

Very important thing is to respect datasheet datas about max allowed current, power dissipation and max input voltage.

 

[jeff77789]

thanks wasnt quite sure how to read the graph at first lol but for me i think my voltage dropout would be around 1v if not 0.5v-0.8v because of low current draw

 

[tpetar]

If there is 1V difference or less like 0,5V-0,8V you can use LDO regulator or simple solution with rectifier diode which make voltage drop by 0,7V (1N4007 for up to 1A max, or you can use any other stronger). Schottky diode usually make less voltage drop from 0,4V-0,5V. Also you can use several diodes in serie, make experiment and try this, this is cheap to try. :wink:

 

[BradtheRad]

In its simplest form you can get under a tenth of a volt drop from a buck converter.
This is with a very light load, and long duty cycle.

Hence a long switch-On time will expose the output stage to practically full supply V.
The diode only creates a PN drop during switch-Off, not during switch-On.