Voltage regulator issue

[Luca]

In my custom PCB i used this regulator with this schematich that i found on the datasheet but the voltage is unstable (+-1V).
What can i do?

 

[PaulS]

Your schematic seems to be copied OK from the datasheet's Typical Application Schematic.
Did you follow the PCB Layout Guide as recommended in the datasheet? These regulators can be picky on the PCB layout.
Did you check/measure the actual component values on your PCB?
Did you use the recommended coils/diode?
Did you check with an oscilloscope on the different signals?
Is something running hot?

Paul

 

[Luca]

I checked the actual component but i didn't followed the layout guides cause i am a noob i its the first time i am usig this smd kind of components.
BTW i don't have acces to oscilloscopes

 

[PaulS]

but i didn't followed the layout guides

That may be the issue - PCB layout is critical.

Paul

 

[PaulS]

What you could do is purchase an MP1584 module (they are cheap and available everywhere) and solder that on your PCB for a first test.

Paul

 

[Luca]

Hi, i built another board and now the voltage is stable but not quite at 5V. Its a little lower like 4.9V. Is it a problem for teensy, servoes and other boards(the say that the VIN should be 5V but pls tell me that 4.9 is good, i don't want to make another board)

 

[PaulStoffregen]

4.9V is fine.

 

[Luca]

Thank you, you literally stopped me from having an hearth attack. Thanks