Hi.
I'm designing a prototype with the ADP2108-3.0V.
Without load, I verified that the output voltage was equal to the input (5.0V).
Somewhere, in the data sheets I read that when the load current is zero, the device doesn't switch, so I decided to place a load of 330 ohms. Then the voltage that appears is 2.25V.
I have placed a load of 100 ohms and the voltage drops to 1 volt with a lot of noise, whereas when it is 2.25 V the noise is almost zero.
I have also read similar problems in other threads, so I put the input capacitor of 4.7 uF next to pin1 of the regulator and it seems that the problem was solved.
But when measuring the voltage on the 330 resistance I noticed that the voltage is 3.36 volts and the regulator is somewhat hot.
I have checked the PCB and it seems that there is no type of short circuit, the only load is the resistance.
Any comment or idea is welcome.
Here I captured an image of the output voltage.
Hi DominusDRR,
Can you send on the board files for your design (Schematic, Layout, BOM) for us to review. You can send it directly to my email if you want.
Also, do you have some scope shot of the switch node together with VIN and VOUT that you can share. (No load and with 330ohm load).
Thanks and regards,
Jefferson
Thank you very much for answering.
I attach the necessary information.
Input voltage of 5 V:
Vout (with 330 ohms load)
Voltage on terminal 4 (SW):
Vout with load:
The PCB is very small and there is not much space, possibly that's the reason:
The elements used are:
The inductor is: LQM21PN1R0MCHD:
https://www.mouser.ec/ProductDetail/81-LQM21PN1R0MCHD The output capacitor is: VJ0805G106KXQTW1BC: https://www.mouser.ec/ProductDetail/77-VJ0805G106KXQTBC
And input capacitor is:
https://www.mouser.ec/ProductDetail/77-VJ0805V475MXQTBC
Thanks again.
I forgot the schematic:
Thank you for the files.
What caught my attention was the layout where I noticed that the SW node (encircled with blue) has three connections rather than having only one (inductor only) - can you clarify. Also, I noticed that the GND pin is connected to a very thin trace and don't see any local via that will connect it to a GND plane to keep the VIN - CIN - GND & SW - L - COUT -GND loop short.
Can you provide me with a snapshot of the layers (on the ADP2108 site) for me to see the connections clearly.