AleksorsistMar 20
Tearing down the world's spiciest e-stim toy
Show threadAleksorsist
The processor had a really strange thermal pad made up of ferrite material, anyone know why this would be used over a normal style thermal pad? I haven't seen this kind of thermal pad before
Mar 20 at 5:49pmMastodon for Android
Show threadAleksorsistMar 20
Was gonna trace out JTAG and whatnot but got sniped by making an xy digital microscope gantry. Not gonna be poking around any ICs with this but it should result in nice high res sitched board images
Show threadThunderbolt93Mar 20
@aleksorsist maybe to prevent the MCU from EMPing itself during discharge (pull the magnetic field lines into the ferrite instead of the silicon)
Show threadAdrian StuderMar 20
@aleksorsist maybe electromagnetic shielding?
Show threadJanaMar 20
@aleksorsist making sure the discharge does not flip a bit or two, not sure which AED model you have there, but a typical biphasic defibrillator can discharge >300J, which typically means >1500V switched. A lot of potential for EMI interference, and an application where a bitflip could mean a much stronger discharge than intended
Show threadJanaMar 20
@aleksorsist I lost my big defibrillator capacitor :( such beautiful danger-objects
Show threadThunderbolt93Mar 20

@janamarie @aleksorsist I have bank of 10x 350uF 1500V caps under my desk ☠

haven't used them for anything (exploding wires, electromagnetic shenanigans) but they were cheap

Show threadDarrell HarmonMar 20

@aleksorsist It's an EMI absorber like this: https://www.kgs-ind.com/products/emc/ferrite-core/sheets-tiles/sd/

Those big QFPs are awful for EMI with the long bond wires.

EMI Suppression Ferrite Tiles: SD Series - KITAGAWA INDUSTRIES America, Inc.

High performance, sintered ferrite tiles for CPU’s high density. Solid ferrite plates designed for EMI absorption on ICs, CPUs, and bus drives running at high clock speeds.

KITAGAWA INDUSTRIES America, Inc.
Show threadAleksorsistMar 20
@dlharmon aaah, makes sense, thanks!