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Self-powered PCM2902 (Elektronik)

verfasst von thunderbolt(R), Saarbrücken, 12.02.2013, 17:00 Uhr

Okay – genau, das was war auch mein Gedanke bzw. meine Rückschlüsse aus den Datenblättern.
In folgendem Dokument http://uk.farnell.com/images/en/ede/pdf/usb_dev_mistake.pdf
findet sich allerdings:

“Since self-powered devices have their own independent power supplies, they can be ON while the host is turned OFF. This causes a potential problem where the small pull-up voltage applied to D+ to enable USB device detection slowly charges up the entire host system and interferes with startup. Self-powered USB devices (including battery-powered devices) must either drive this pull-up directly from VBUS or turn it off via software control using a VBUS sensor.”

Nach Beschaltung des PCM2902 wie im Datenblatt dargestellt, wird dieser Pullup (1.5K) von VDDi (Pin 27) gespeist. Ich nehm jetzt mal einfach an das hier das obige geregelt wird? :confused:

Zu den Spannungsdifferenzen an verschiedenen Masseanschlüssen – PCM, externe Spannungsreferenz (LT1021-5) als auch der Messverstärker haben die gleiche Masse. :lookaround:

antworten

Gesamter Thread:

Self-powered PCM2902 - thunderbolt(R), 11.02.2013, 19:18
Self-powered PCM2902 - Hartwig(R), 11.02.2013, 22:33
Self-powered PCM2902 - thunderbolt(R), 12.02.2013, 17:00
Self-powered PCM2902 - Hartwig(R), 13.02.2013, 08:50
Self-powered PCM2902 - thunderbolt(R), 13.02.2013, 18:06
Self-powered PCM2902 - Hartwig(R), 13.02.2013, 23:57
Self-powered PCM2902 - thunderbolt(R), 14.02.2013, 15:04
Self-powered PCM2902 - PeterGrz(R), 14.02.2013, 15:42
Self-powered PCM2902 - Hartwig(R), 14.02.2013, 17:11
Self-powered PCM2902 - thunderbolt(R), 14.02.2013, 17:53
Self-powered PCM2902 - Hartwig(R), 14.02.2013, 20:19
Self-powered PCM2902 - thunderbolt(R), 18.02.2013, 17:36
Self-powered PCM2902 - Hartwig(R), 18.02.2013, 20:52
Self-powered PCM2902 - thunderbolt(R), 19.02.2013, 18:36
Self-powered PCM2902 - Hartwig(R), 19.02.2013, 23:00
Self-powered PCM2902 - Hartwig(R), 20.02.2013, 15:22
Self-powered PCM2902 - thunderbolt(R), 20.02.2013, 19:17
Self-powered PCM2902 - Hartwig(R), 20.02.2013, 19:44