symbol [~]
I ran into this wiring symbol today and haven't been able to find out what it means. Somehow internet search of "criss-cross wire schematic symbol" wasn't especially fruitful.
Is this something I need to worry about or is this just a representation of a USB connection?
It looks like a solder bridge. Sometimes there can be a jumper that you need to put, sometimes it is just two very close pads that you join with a blob of solder.
Okay, that is an (unfortunately) typically crappy Chinese datasheet. No ratings at all that I can see on the diode.
One could begin to harbor doubts about its very existence, despite the usefulness of a diode in that position in certain ballast topologies (those with push-pull dual transistors, it's not in the right position for a general inductive load).
Here is a proper datasheet for a similar type of part (Fairchild FJP3307D) that actually shows ratings for the diode (Vf = 2.5V maximum at 3A & 25°C).
They don't say whether the diode is a separate part in the same package (as is done with some IGBTs) or whether it's an integrated feature, but that would be fairly easy to find out from a sacrificial sample or two.
Here is a schematic of the type of lamp that might benefit from such a component, from this manufacturer:
When Q1 turns off, then D3 conducts. Similarly when Q2 turns off then D2 conducts. Criss-cross.
Best Answer
That's showing the internal workings of a typical USB cable. The shield (top line) is connected to the chassis of both devices. USB Data- and USB Data+ are twisted together for better noise rejection, at the cost of increased capacitance between the two. Likewise, power (VBUS) and ground are twisted for the same reason.