About Mounting Precautions and Track Lenghts

Hie everyone,

I want to design a PCB Board of 100mm X 100mm.

In my Application, We are using oscillator pins. So, it is mentioned in Datasheet of Microcontroller that

The Components such as a resonator, resistors, and capacitors connected to the OSC1 (OSC3) and OSC2 (OSC4) pins should have the shortest connections possible.

But, the exact value of Shortest connection is not mentioned in datasheet.

Can anyone suggust me approxiamated length of Shortest connection On PCB Board

Regards,

Anirudh THABJUL
Hardware Engineer
Lansa Diffusion, Paris, France

Just start the board layout placing these as close as possible to the mentioned pins. I’d say 10 mm is too much already but it could still work depending on many factors.

I’m guessing, since the shortest connection is basically 0, they left it out. My preference (I’m guessing, like Dolganoff) is to start with the IC and distribute components around it, roughly in order of priority of placement/routing:

Crystals > Inductors > High speed comm lines (SPI, USB, etc) > Small decoupling caps (0.1uF-ish) > Medium decoupling caps (1~10uF) > Analog lines > PWM lines > GPIOs (non-frequency input/switching) > resistors / ferrites / diodes / etc

Of course every application requires specific handling / exceptions.

IMHO: If the oscillator lines end up over 10mm you’ve done something wrong from the start.

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thq for your valuable information…! :smile: