# What is this SB component on schematics

Is the SB19 component a "jumper" (0-Ohm resistor)? On the board itself, some of these are placed, and some aren't, leading me to believe that's what they are. There aren't any 0's on them, though.

EDIT: I put 0-Ohm resistor in parentheses because some people thought I was asking if it was a jumper or 0-Ohm resistor, when I meant that it could be referred to by one name or the other. My bad on the wording.

• If you have access to the board you should be able to see what it is. There's no distinction between a jumper and a 0$\Omega$ resistor in, say, 0603 parts, just different names for the same thing. From "SB" (shorting block?) it could be that kind of thing, or something else entirely. – Spehro Pefhany Sep 23 '14 at 19:46
• It's just a little black SMD. No markings. – MrUser Sep 23 '14 at 19:48
• @MrUser likely a 0 ohm resistor then, ohm it out to be sure – ACD Sep 23 '14 at 19:48
• Zero ohm resistor, AKA jumper. Some have markings, some don't. – Spehro Pefhany Sep 23 '14 at 19:49
• surely SB stands for solder-bridge. – KyranF Sep 23 '14 at 20:03

It's a solder bridge.

I'm guessing that you're looking at schematic on page 37 of this document:

http://www.st.com/st-web-ui/static/active/en/resource/technical/document/user_manual/DM00039084.pdf

If so, then SB19 is documented in table 4.11 on page 20, under "Solder Bridges". This solder bridge allows you to add/remove the pulldown resistor on the BOOT1 signal.

• Solder Bridge. Aha. I wasn't looking at that exact document, but at another STM discovery datasheet. I should have RTFM, not looked at it. Thanks. – MrUser Sep 23 '14 at 20:15
• Interesting. I would call these solder bridges, not the SMT jumpers as shown in the photo. Maybe it loses something in the translation. – Spehro Pefhany Sep 23 '14 at 20:19
• I suspect at the schematic level, designers may use "bridge" and "jumper" nomenclature interchangeably given that they are electrically identical. – payne Sep 23 '14 at 20:21
• @payne It strikes me that perhaps (hard to tell from the photo) they may be designed to work either way and the ones that are installed by default (at the factory) are machine-populated with 0$\Omega$ resistors. That would be the most efficient approach- otherwise hand work would be required. – Spehro Pefhany Sep 23 '14 at 20:25
• Update: schematic is p28 not 37 in the document. I'm guessing the document changed. – Gabriel Staples Mar 8 '18 at 2:11