On the attachment there's a special diode D17 looks like a pair of zener diode facing each other. why use that instead of the normal diode clamp of D15 like shown? what's difference of D17 versus D15?
finally , what's F3? why that line in the middle? meaning variable?
what's this special diode on the Pi board
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Re: what's this special diode on the Pi board
F3 is fuse otherwise known as polyfuse they're designed break and reset when current usage exceeds their specified rating.
D17 is a TVS diode this prevents voltage spikes appearing on the +5v supply rail or if input voltage is too high and out of specification.
http://en.wikipedia.org/wiki/Transient- ... sion_diode
D15 is an ESD electrostatic discharge protection diode this stops nasty potential differences appearing at the SoC input / output pins when connecting to TV or audio amplifier.
http://en.wikipedia.org/wiki/Electrosta ... ive_device
Richard S.
D17 is a TVS diode this prevents voltage spikes appearing on the +5v supply rail or if input voltage is too high and out of specification.
http://en.wikipedia.org/wiki/Transient- ... sion_diode
D15 is an ESD electrostatic discharge protection diode this stops nasty potential differences appearing at the SoC input / output pins when connecting to TV or audio amplifier.
http://en.wikipedia.org/wiki/Electrosta ... ive_device
Richard S.
Last edited by redhawk on Sat May 31, 2014 8:37 pm, edited 1 time in total.
Re: what's this special diode on the Pi board
F3 is variable because polyfuses increase their resistance once over their "hold current" level. They effectively go open circuit (really just very high resistance) above their "trip" rating. When power is removed they slowly settle back to a low resistance state.