Thats internal in PSOC unless you wanted to use an external reference. Allow
for the option to bypass to a fixed pin the internal reference to minimize ref
noise at high resolutions. There is a dedicated pin for this use to implement
the Vref bypass.
2) Protection circuits
To protect pins from transients that try to take pin > Vdd + .5 or < Vss - .5.
These transients can cause latchup of PSOC or at least unpredictable
3)Internal Boost Regulator
For operation on singler cell battery applications, or very low voltage rail
that you need to boost to allow PSOC to run at a higher voltage.
Some useful references -
http://www.cypress.com/?rID=43337 AN61290 - PSoC® 3 and PSoC 5LP Hardware Design Considerations
http://www.cypress.com/?rID=39677 AN57821 - PSoC® 3, PSoC 4, and PSoC 5LP Mixed Signal Circuit Board Layout Considerations
http://www.cypress.com/?rID=40247 AN58827 - PSoC® 3 and PSoC 5LP Internal Analog Routing Considerations
http://www.cypress.com/?rID=39974 AN58304 - PSoC® 3 and PSoC 5LP – Pin Selection for Analog Designs
Use a board with 2 mill copper so you can replace the parts you burn out. Use single sided board.
Use a separate 5 volt and 3.3 volt regulator and put current limiting resistors in line. You will most probably use components with different voltage levels.
Put current limiting resistors or use opto couplers on all IO. This is where you will fry most parts.
Get in the habit of using cable connectors that are shrouded. A DB25 connector on the board with a plug that has removable pins works well and is durable.
Some boards can be hard to program if there is already a program running that uses IO such as PWM or I2C or something of the sort so if you can put headers and jumpers on all io pins.
Thank you for helping me!
You suggested using a separate 5 volt and 3.3 volt regulator. I get confused for this part. Could I only design 3.3 volt power for my board. Is 5 volt necessary? Thank you:)