TI MC33063ADE4 Step-Down PCB layout

Discussion in 'Analog & Mixed-Signal Design' started by sc0tch, Nov 7, 2018.

  1. sc0tch

    Thread Starter New Member

    Nov 6, 2018
    I'm Travis and this is my first post here. I am a software engineer building a small business. I am currently redesigning a product that is overly complex in the sense that it uses several junction boxes, PCB's, and the sensors signal is very noisy and requires allot of inaccurate "speculation" in the code to use this noisy signal. What the product does is measures beer flow through a draft beer systems lines using a driven impeller and a hall effect sensor. driven by a raspberry pi using 5V with a voltage divider to attenuate the signal to 3V4 . I currently have 8 sensors on the Pi, plus a thermal sensor, a display, and some switches and buttons.

    I'm working on a new PCB utilizes an MC33063ADE4 switching voltage regulator. The regulator will primarily be used to power a raspberry pi in my project. I am choosing to power the project using 12V AC-DC power supply and step this down to 5V to power my pi0w. I want to use 12 V for eight hall-effect water flow sensors which are rated from 3-12VDC. I want to supply 12V to the sensors for two reasons, one the distance the signal must travel over a 22AWG conductors in CAT5. And two the sensors appear to have a much cleaner square wave signal at 12V than they do at 5V or 3.3V. My plan is to then bring the signal down to 3.3V using a voltage divide before feeding it to the raspberry pi's GPIO.

    Mostly what i'm looking for is feedback if this is electrically correct, and if there is any advice in saving space in this circuit as real estate on this PCB will be at a premium, after the RJ45 connectors, voltage dividers, etc... are added.

    Also is it best practice to use a voltage divider from 12V down to 3.3V into GPIO or would it be better practice to drive a MOSFET with the 12V from the sensor at the gate and a 3V3 and the Pi's GPIO at Source and Drain.

    Thanks very much everyone!