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10.8V Pi 2 survives

Former Member

I am so surprised how strong the Raspberry Pi 2 is. I was attaching  a motor controller two it and accidentally connected a 10.8V battery to the 5V pin. The Pi turned off and wouldn't turn on, but after a few minuets, I tried again and it worked!

  • Almost nothing in the 'pi uses 5V.

     

    5V is just the power-rail where all power comes from. The Pi 2 has two or three switching regulators near the micro USB power connector and probably another one for the CPU core voltage inside the CPU.

     

    Even though some (Among others, the BCM2835) chips state: "5.5V Absolute maximum limit", that limit might be much higher. But by claiming that limit in the datasheet the manufacturer can later change things around and end op with the real limit lower, but still above 5.5V.

     

    Writing specifications is an art: You need to make the chips usable for the users, but also allow as many changes as possible for your company so that in the future a (forced or not) update will not move the chip outside the original spec.

    Microcontrollers have rules about "reserved" bits in registers. This way they can for example sneak a new peripheral in the running production of a chip. The customers pay for the setup-costs of the "chips with the new feature" while the engineers can test out their new silicon.

     

    Anyway, with the raspberry pi, just a bunch of "DCDC converters" is hooked up to the 5V rail. Those are more  tolerant of higher voltages than say a "5V HCT chip".