QFN20 breakout board
In my search for I2C GPIO extension boards I’ve now ordered some TI PCF8574 chips. These support 8 GPIO and 8 I2C addresses but no PWM. As I’ll potentially be wanting these for production use everntually - and because I want to buy the cheapest stuff available - I’ve gone for the VQFN20 package (PCF8574RGYR). This is a 3.5 mm x 4.5 mm chip with 2 pins on 2 sides and 8 pins on the other two sides.
The prototype breakout board is available to order on OSH Park below:
As with the QFN28 board, there’s silkscreen areas front for the chip name, and on the rear for a serial number.
I managed to find a .bxl CAD drawing of the package on TI’s website, downloaded the free copy of Ultra Librarian, exported to an Eagle scr, and then imported into an Eagle library. This saved me drawing it all myself in Eagle.
Looking at it now maybe I should have made it rectangular with 10 pins on each side. But I like squares.
A snip at $2.60 for 3 of these.comments powered by Disqus