Hi, I am going to design a DC-DC boost converter which will input from 5V and output 12V/1A.
I have question that to produce 12V/1A, boost converter will be drawing atleast 5V/2A from input source.
What would happen if I connect the input of DC-DC to USB port of computer which will be able to only provide upto 500mA current. Will it Burn the USB port of my laptop ?
Can you please tell me if there is any safety feature which can help me preventing from damaging input source if it can’t supply the required current ?
In my application Input source can be USB port of laptop , USB adapter with 1A current and USB adpter with 2A current, but how DC-DC converter will sense how much current the input source can supply so that it will not draw current more than the source can supply.
Assuming 100% efficiency, since you need 12W (12V * 1A) of output power, that means that you’d require at least 2.4A (12W / 5V) of input current to support your application.
If we modify our assumption to say 90% efficiency, then the input supply would have to be rated for at least 2.7A (2.4A / .90).
In short, you must provide the converter with an input supply with a higher current limit for your application to work. Otherwise when the load transient happens the output will crash since there is not enough energy to keep it up.
As for the safety features, it’s possible to set the current limit of some boost converters so that they don’t trip over-current protections on the input supplies. It’s difficult to know how your USB ports are designed, but one would expect that they wouldn’t be damaged during this event. They simply won’t be able to sustain the 12V supply while it is loaded.