Toinen merkittävä seikka on USP-portin antama virta.
Kokeilin erillisellä Hub:lla, jossa on oma virtalähde ja jaksaa syöttää paremmin, mutta ei siitä ollut apua, koska siellä on kaapelt nipussa, joten ne olisi pitänyt repiä auki.
Samsung 750 EVO SSD specs:
250GB:
Active Read/Write (Average): 2.4W / 2.8W, ---- =
0.56 A. 5 VDC syöttö. 3.3 VDC syöttö 0,85 A.
Idle: 50mW
Device Sleep: 6mW
Seuraava artikkeli kertaa miten eri SSD repii virtaa. Joten jos läppäri on suuniteltu 250 Gt SSD:lle, niin riittääkö se syöttämään 2 Tt:n SSD:tä ?
https://ssdsphere.com/ssd-power-consumption-comparison/Seuraavassa kerrotaan mitä saa tehä ja mitä ei.
https://electronics.stackexchange.com/questions/5498/how-to-get-more-than-100ma-from-a-usb-portI that it differs from motherboard supplier how good the power supply for the USB is. Some cheap B-brand manufacturers may just link the +5V of the power supply down to the USB port. Some better ones may actually include the whole package for overcurrent protection etc.
I got a sweex 4-port (el-cheapo, costed me like 10 euro's) USB hub so I don't have to get under the desk all the time for an USB connection. This sweex port clearly doesn't have any protection. I have smoked shorted MOSFET with it once, which its rated current was 3A.
Anyway, my point I want to make is that no matter what your project is, you probably will not want to get over 500mA of current drawn from a USB port. As a one off, maybe.. if you want to risk blowing it up on your own behalf. Certainly not for anyone else.
I'd like to think that the power provided by USB is mainly to make it possible to have communication with the real device. You might feature an isolation circuit to give better protection for USB hosts. I'd certainly not take USB as a universal 5V power supply, because adapters can do that much better (and in the long-term probably cheaper).
