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In the Air Design Challenge - Pollen & Allergen Sensing – Post 4 (Preparing the InTheAir Power Board)

tomaja

Previous posts:

In the Air Design Challenge - Pollen & Allergen Sensing

In the Air Design Challenge - Pollen & Allergen Sensing – Post 1 (Pollen Sensor)

In the Air Design Challenge - Pollen & Allergen Sensing – Post 2

In the Air Design Challenge - Pollen & Allergen Sensing – Post 3 (AirVantage Intro)

 

Preparing the InTheAir Power Board

 

I’m having trouble with TI LaunchPads delivery but I have to make some advance here even without having them with me in order to complete the project on time.

First, I would like to say thanks to Christian Defeo for being very helpful and patient when it comes to shipping the material and resolving customs issues. Also, I would like to say thanks to who was kind enough to share his work on the solar Li-Ion battery charger based on TI’s BQ25504.

 

I chose to make a power supply board in form of a LP BoosterPack.

TI’s BoosterPack template was used to develop my own board that fits to Launchpads. This template can be obtained from the following page: Build Your Own BoosterPack for TI LaunchPad

For the actual PCB design I use Eagle PCB Design software provided by CadSoft - CadSoft EAGLE PCB Design Software - Circuit Board Design Software.

 

This PCB design will be my second real attempt in making a circuit design so I will have to be very careful. In my first attempt, I created a VFD clock based on MSP430G2553 and after my boards arrived back from manufacturer I realized that I made a couple of design errors. Luckily, those were small errors that I managed to resolve using a sharp knife and a small peace of wire image

 

InTheAir Power Board will host:

  • Battery charger powered by a solar cell
  • 3.3V power supply
  • 5V power supply

 

Lukasz’s battery charger circuit is used as the basis for my booster pack. I removed the connectors used for resistor connections.

At the moment, my board hosts the charger based on BQ25504 from Texas Instruments. After I made the following picture I realised that Lukasz's connectors are not 2.54mm pitch so I will change them for 2.54 pitched ones (kindly provided by Würth Electronics: Serie 2109 - 2.54mm Horiz. Entry WR-TBL - Product Catalog Electromechanical Components).

 

Here’s the current state of my Booster Pack:

image

 

EDIT: After I changed the connectors there's much more space left for other components:

image

I followed some advices on using vias to avoid making unwanted antennas.

 

For 3.3V supply, I will use TPS61291 Boost Converter.

For 5V supply, TPS61200 Boost Converter will be used.

Both components have very detailed data-sheets with example usage circuits. It will be fun to fit them on my board.

 

Eagle files will be uploaded as soon as I complete the design.

I’m sure more experienced guys will have some comments when I complete. I will wait a couple of days before I send it out for manufacture.

 

As for the soldering, I have a lot of experience there so I expect that will not be too much of a problem.

 

Dragan