Is internal oscillator is less battery drainer ? is it “professional” enough to use internal for mass production?
I made some rough measurements with a 328P running a blank sketch at 5V and room temperature:
328p, 5V, room temp, blank sketch loaded
14.5mA - 16MHz xtal, full swing, fast rise (F7 D9 07)
13.4mA - 16MHz xtal, low power, fast rise (FF D9 07)
11.1mA - 8MHz xtal, full swing, fast rise (F7 D9 07)
9.7mA - 8MHz xtal, low power, fast rise (FF D9 07)
8.6mA - 8MHz internal (lfuse:C2 hfuse:D7 efuse:07)
I’ve never been able to find this information in the datasheet. The supply current for 5V and 8MHz is listed as 5.2mA typical and 9.0mA maximum.
Setting a lower capacitor, hurt the final frequency that stay const on 8Mhz-xMhz , or is it causing an unstable frequency ?
It will likely work fine but may run a tiny little bit faster than 8Mhz. Or it might turn out that 15pF is the perfect added capacitance for your board.