AlGeorge
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Hi I have a job to provide a LED signal when event occurs. It needs plenty of LED brightness which means we have to use Red and Green LED only. Also, the main problem is no LED are happy with 3v driven by PIC micro - they are below the output curve - 4.5v is much better.
I dont believe that there is any need of series limiting resistor at 3v button cell supply; am confident that the PIC is more than capable of handling the few ma when switched on, despite all app note showing series resistors. When the PIC is set as output, it has series resistors in the drive output in any case.
Interested in any others comments on this typical scenario, bearing in mind minimum parts count for maximum LED output, with constraint being it must be button cell and preferably only one battery (more than one leads to reliability problems in battery connectors, and discharge linearity.
Cheers,
Alistair George.
I dont believe that there is any need of series limiting resistor at 3v button cell supply; am confident that the PIC is more than capable of handling the few ma when switched on, despite all app note showing series resistors. When the PIC is set as output, it has series resistors in the drive output in any case.
Interested in any others comments on this typical scenario, bearing in mind minimum parts count for maximum LED output, with constraint being it must be button cell and preferably only one battery (more than one leads to reliability problems in battery connectors, and discharge linearity.
Cheers,
Alistair George.