Gregory's ServerOn second thought, the isolated DCDC converter on my board only has functional isolation, and this already seriously limited the working voltage of the entire system. It's kind of pointless to design the rest of board for reinforced isolation per IEC 60950. I guess it's time to remove the slots. #electronics
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 There are more gotchas. > Clearance: 8 mm Then the 8 mm clearance is immediately violated, officially, in the recommended footprint at the end of the datasheet. #electronics #usb Another pitfall is the IPC-2221 standard in most PCB calculators. Its clearance requirement can get ridiculous for some use cases because of the stepwise definition, yet insufficient for other uses cases (reinforced insulation). "Friendship ended with IPC-2221, now IEC 60950 is my best friend!" #electronics PCB ordered. Added common-mode chokes at both sides of the isolated converter hopefully to suppress some noise across the barrier. Also removed the slot - the SIP DCDC module only has functional isolation, so increasing the creepage distance further is pointless... #electronics Hopefully I won't accidentally kill myself later in the dielectric withstand voltage test by the 3000 volts HiPot tester. LIke many on the Fediverse, https://ihatebeinga.live is a thing, but a HiPot tester is just a terrible way to die. #electronics My USB 2.0 isolation board is working. The Texas Instruments chip ISOUSB211 works as advertised, it really is the first USB 2.0 high-speed (480 Mbps) galvanic isolation chip on the open market. I'll release all the design files tomorrow. #electronics #usb TI ISOUSB211 development board design is now public. This TI chip is the first ASIC capable of doing USB 2.0 High-Speed (480 Mbps, not 12 Mbps) galvanic isolation on the open market. As always, #Lain must be loved. https://notabug.org/niconiconi/isousb211 #electronics #usb |
After closer inspection, it turned out that the astonishing 1500 volts (AC) & 2100 volts (DC) "Maximum Isolation Working Voltage" boasted by Texas Instruments is only an industry standard for digital isolation *components*, while authentic, it's not for complete *systems*.
When you actually use the system-level safety standards used by national regulators like IEC 60950 and IEC 60664, you'll find in a real application, the 8 mm creepage distance at the chip package limits the working voltage to no more than 800 volts AC (Material Group 1, Pollution Degree 2, Reinforced Insulation). So much for the marketing.
> The large print giveth and the small print taketh away. -Tom Waits
> The nice thing about standards is that you have so many to choose from; furthermore, if you do not like any of them, you can just wait for next year's model. - Andrew S. Tanenbaum
#electronics #usb
After closer inspection, it turned out that the astonishing 1500 volts (AC) & 2100 volts (DC) "Maximum Isolation Working Voltage" boasted by Texas Instruments is only an industry standard for digital isolation *components*, while authentic, it's not for complete *systems*.
When you actually use the system-level safety standards used by national regulators like IEC 60950 and IEC 60664, you'll find in a real application, the 8 mm creepage distance at the chip package limits the working voltage to no...