[TriEmbed] Ground Confusion
Charles McClelland
chip at mcclellands.org
Wed Apr 30 18:38:06 CDT 2014
To all,
I have been looking at a way to improve my battery life for my trail traffic counters. I am currently using a linear power supply and with Sleep and other power savings methods, I can easily get a week on battery with 4 AA batteries (my board operates at 3.3V with very low average current and I estimate a 150mA max).
However, I want to do better:
- For the SD Card sensor - to go a week on just three AA cells
- For the wireless sensor - to go 6 months with a 6V lantern battery
I started looking at Texas Instrument’s buck-boost switching power supply chips and using their WeBench tool, designed this circuit.
What is better, TI sent me three of these chips for free!
My question is in how I am translating their schematic into an EAGLE file I can ask OSHPark to make for me. The schematic has both Control Ground and Power Ground. And the design report says "Use a common ground node for power ground and a different one for control ground to minimize the effects of ground noise. Connect these ground nodes at any place close to one of the ground pins of the IC.”
I decided to use a Sparkfun solder jumper which is normally closed to make the connection between GND and pGND. But do any of you know a better way - or could you take a look at my EAGLE files and tell me if I did this right?
Here are all the files on drop box - https://www.dropbox.com/sh/9qdzturvffr66do/3QMS0SvYHP
Thanks for the help. If this works, happy to share the design for those who are looking to get more life out of their batteries.
Chip
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