MPL3115A2 3.3 vs 5v rails

General project help for Adafruit customers

Moderators: adafruit_support_bill, adafruit

Please be positive and constructive with your questions and comments.
Locked
User avatar
mrbandit_stg
 
Posts: 11
Joined: Mon Oct 04, 2021 5:03 pm

MPL3115A2 3.3 vs 5v rails

Post by mrbandit_stg »

FETS for 5V support
FETS for 5V support
FETS.png (5.25 KiB) Viewed 147 times
I'm looking at the MPL3115A2 breakout schematic. I am looking for a reality check.

It appears that if I connect the 3.3 pin to a 3.3v source, but NOT connect the 5V, the I2C lines should operate at 3.3v, because the output of the FETs are not being pulled to 5V. The FETS should conduct because the baes is pulled to 3.3v, therefore the FET is logically just a wire,

Is this correct? I need 3.3v, and would hate having to put a 5v power on the boards, along with the voltage level shifters.

Please advise ... yours ..., bandit

User avatar
adafruit_support_carter
 
Posts: 29150
Joined: Tue Nov 29, 2016 2:45 pm

Re: MPL3115A2 3.3 vs 5v rails

Post by adafruit_support_carter »

The 3vo pin is the power *output*. Do not apply power there. Power should be applied to the Vin pin.

For 3.3V usage, just power with 3.3V at the Vin pin.
https://learn.adafruit.com/using-mpl311 ... -2982486-2

User avatar
mrbandit_stg
 
Posts: 11
Joined: Mon Oct 04, 2021 5:03 pm

Re: MPL3115A2 3.3 vs 5v rails

Post by mrbandit_stg »

thanks! works like a champ!

Locked
Please be positive and constructive with your questions and comments.

Return to “General Project help”