USB Type C standard - Page 1
Forum section: electronics / projects

author: tszaboo
author_rank: Super Contributor
timestamp: December 19, 2020, 04:42:36 pm
content: So the gurus at USB-IF gave as a standard. It was called USB. And it was good. 12mbit/s speed. Nice connectors. And everyone was making this connectors. It was through hole, the people could solder it. You could replace one connector with another. They were the same size, they were the same shape. They were standardized. They were universal. As the name suggested.Fast forward to 2016. A new cable and connector is introduced. It places back USB into the 3 dimensional space, where your cable is not in the so called USB-superposition (always the wrong way, until you observe it). The standard looked good on paper.And then they started making the connectors for it. I keep looking at datasheets, and footprints. The only thing that comes to my mind is this:"You Maniacs! You blew it up! Ah, damn you! God damn you all to hell!"So that so called universal connector exist in 7 pin configurations, 6,8,14,16,22 and 24 pins on it.It is either SMD with two rows of pins (forget manually soldering it). Sometimes you even have to mill out the edge of the board for it. Can I route this connector? Not unless you have 6 layers, all the connections needs to be criss-crossed, make sure to have good signal integrity. And dont place any vias under the connector, we all know why.It can be TH-SMD combination. Worst of both worlds, nothing to talk about. At least, here, you might have a chance to be able to route it.I just saw a connector, which is SMD, and of course it has pins on both sides of the board. The pick and place machine probably needs to be possessed, and the board house will love placing paste on both sides of the board at the same time.Some of these I cannot even create a footprint for. I'm looking at the recommended footprint, and it has overlapping pads. And they have pin A1 B1 A3 B4 and so on, and they forget to tell you which pin is which on the footprint.Is there a connector, which would be: I dont care about all the high speed crap, I just want my D+ D- 5V GND pins, and use the magic of reversible connector. The closest I've come to this was a 12 pin one, where I would only need two 5.1K resistor extra(or else).I've spent 2 hours finding two connectors with matching footprint. Because I refuse to vendor lock-in myself for a stupid connector. I don't think it exists! I think everyone deliberately made slightly different incompatible connectors, just to make our lives miserable.What happened here? Is this the punishment for something we made?

author: ConKbot
author_rank: Super Contributor
timestamp: December 19, 2020, 07:55:20 pm
content: Only thing worse than routing a USB-C is a micro-HDMI. All the misery and then some, none of the benefits. No high power available in a single cable, no repurposing the alternate mode for other things. Just dual-row SMD only with naff-all space for vias on the hidden row on a lot of versions, oh and you need inter-pair length matching too, but good luck finding electrical lengths of the two different rows in a datasheet. At least they were reasonable enough to have the power pin somewhere ok for routing the power trace to. (IIRC standard is tens of mA, but common practice is ~0.5A available to run active adapters)Also, USB-C is kind of a head scratcher when it comes to protecting from both ESD and adjacent-pin shorts. 20v protection for CC/SBU can be found. the coupling cap should protect the TX output somewhat (6.3v ceramic cap, 20v... super sketchy but can probably take it for short amount of time... maybe) Good luck on the RX inputs though. hopefully it faults out before it negotiates for higher power if you have conductive junk or damaged pins in a connector. Otherwise the 20v/2-3A is just gonna smoke an ESD diode, then the mux.

author: ejeffrey
author_rank: Super Contributor
timestamp: December 19, 2020, 09:02:33 pm
content: Quote from: blueskull on December 19, 2020, 04:53:25 pmNot just that but 40 Gbps while backwards compatible with 25 years of standard revisions down to speeds of 1.5 megabit. Oh, and it needs to deliver 100 watts. In either direction.It's a bit absurd that we are commonly plugging mice and keyboards into 40 gigabit connectors.

author: sleemanj
author_rank: Super Contributor
timestamp: December 19, 2020, 11:49:30 pm
content: The 12 pin ones should be fine, something likehttps://lcsc.com/product-detail/USB-Type-C_Korean-Hroparts-Elec-TYPE-C-31-M-14_C223907.htmlyou'll need the two pull downs if you intend to do USB-C to USB-C, but of course if you are only ever doing USB-A to USB-C then you wouldn't need them since they have nowhere to connect to the host anyway.But it's a couple of microscopic resistors straight to you ground plane so you might as well just add them.

author: jbb
author_rank: Super Contributor
timestamp: December 20, 2020, 06:28:37 am
content: Quote from: sleemanj on December 19, 2020, 11:49:30 pmYeah. And note you need twoseparatepulldowns,as the Raspberry Pi people were embarrassed to find out...

author: tszaboo
author_rank: Super Contributor
timestamp: December 20, 2020, 09:04:14 am
content: Quote from: sleemanj on December 19, 2020, 11:49:30 pmOh, I've seen that connector. that connector has pins right next to each other, with shared pad. Nice isn't it. You create the schematic create the footprint, scratch your head for like 5 minutes (why is there less pins on the PCB?),realize what happened, spend 30 minutes forcing your CAD package to do what is normally forbidden by design rules. And then give up, restart schematic.It is a connector called:"Reference Footprint for a USB 2.0 Type-C Single Row Right Angle Receptacle (Informative)"And then I wanted a compatible one, from Digikey. I found 3 that was ever so slightly different.One had different SMD pads, the other different mounting holes for the shielding, a third one had a slot hole for the locating pin. Why would you ever want a 0.6mm diameter slot hole for a locating pin?For microUSB, you can replace one with another without opening the datasheet.

author: sleemanj
author_rank: Super Contributor
timestamp: December 20, 2020, 10:39:24 am
content: Quote from: NANDBlog on December 20, 2020, 09:04:14 amYeah that's why it's specified as 12 pin and not a 16 pin, those 4 pairs on the outside are treated as 4 wide pins instead of 8 narrow ones.

author: Raj
author_rank: Frequent Contributor
timestamp: December 22, 2020, 01:56:55 pm
content: Good thing usb-c modules pcb exist (1.png)I mostly still use 2 pin b micro (2.png)