So i designed a board with drv8316 and encountered a problem with the buck of the DRV8316 by default when the nsleep pin is pulled high it should output 3.3v right?. From what i read in the datasheet it says like that but i get 2.5v only. I have attached the schematic below
Also if you could point out the mistakes, inefficiencies or how i could improve my design would be really helpful.
Thank you,
Kavin
Does it work when the USB is plugged in? Otherwise it looks like you’re trying to pull nSLEEP high using the output of the 3V regulator, which is powered by the buck, which doesn’t turn on until nSLEEP is pulled high by some other source. It baffles me how the hardware designers could have overlooked such an obvious paradox. Surely it wouldn’t have been impossible to invert the polarity on that pin so you pull it low to activate the buck.
What is the purpose of the eight 10nF capacitors between +BATT and GND? Are they supposed to be 10uF for a bit of bulk capacitance?
Hmm, hopefully someone who’s actually used it before can advise then.
I have used it before, and the buck worked for me.
As Deku pointed out the bulk capacitance has to be higher, but you’ve already mentioned it’s just a typo.
The “chicken and egg” problem we already discussed on discord, and you’ve tried different methods of pulling nsleep high.
The diode D2 is marked Zener type in schematics but I think it should be a schottky or just a normal diode.
The circuit around Q1, I’m not sure I agree with it 100% but it should work as long as VDD is just a small amount higher than VBUS…
At which places in the circuit are you measuring the 2.5V?
Thanks for the looking into it. I have found the issue thanks to you but i don’t know what happened the buck was indeed generating 3.3V but the output of the SM3407 was only 2.5V. I tried removing the diode connecting it to the VBUS and it worked. I don’t understand why that happened.
Is there a better way to isolate the USB and the BUCK of the DRV???
