Hello Vasile,
On Sep 1, 8:15 pm, vasile surducan <[email protected]> wrote: > Everything depends on the project status volume. For 100pcs an LDO of 1euro > is damn expensive. > At volume LDO (at 100pcs) must be in 0.15-0.2euro/pcs > If wrong choosed, 3.3V and 5V are an issue, you can see this after the first > 100 programming times... when need to switch jumpers. No probnlem with one > hobby board. I don,t understand what you mean, Who is going to build 100pcs ? > Thermal dissipation on 3.3V could be also a problem. Imagine a communication > bus at 120mA (maybe you don't need it, like RS485) and a common unstabilised > power supply of 9V input (need 4V dropout on common/inexpensive 5V LDO). The > 3V3 stab will dissipate 9V-3.3V =5.7V*0.12A = 0.7W You are right But, we need a LDO because we want to get the 3.3V out of the 5V so we also have 3.3V when we power the board from USB or serial. So Recalculating, you will have 1.7V*0.12A=0.204W looking at LD1117 datasheet Rthj-amb = 50 °C/W on a TO220 witch result in (0.204*50) = 10.2°C increase of temperature. So total temperature of the LD1117 will be at T ambient 22°C + 10.2°C = 32.2°C. This is not a big problem. What we need to describe in the manual going with Jaluino Medium is the power dissipation In the 5V regulator during the use of a relative high ac/dc PSU and than the possibility to add a heatsink . > Size can be another problem if 10% of your board is occupied with a TO220 > which is loaded with 1W. > For hobby it's good, but those hobby projects will be someday production > projects... I see this based on your complicated code. > Don’t see why, this is more a hobby/testing board, for production its much cheaper to design a board special for the application you need it for Greetz Richard --~--~---------~--~----~------------~-------~--~----~ You received this message because you are subscribed to the Google Groups "jallib" group. To post to this group, send email to [email protected] To unsubscribe from this group, send email to [email protected] For more options, visit this group at http://groups.google.com/group/jallib?hl=en -~----------~----~----~----~------~----~------~--~---
