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I'm designing a circuit and want to power it through a USB Micro B connector. I have already installed the connector on my board, but after connecting the USB female connector of the wire to my computer, I don´t get any voltage on the Micro USB B connector. How must I connect it? I used to use a USB B connector on my through hole prototype and it worked very good but it had only 4 pins. Can anyone help me?

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    \$\begingroup\$ You'll need to provide the datasheet of the connector for us to be of much help. \$\endgroup\$ – Adam Davis Jan 14 '14 at 0:58
  • \$\begingroup\$ If you don't want to wait for us, one way to solve your problem is to simply attach your board to a generic USB charger, then carefully probe all five pins to find out which two are ground and 5V. The data pins may have voltage on them, but shouldn't be connected to ground or 5V. Then use those pins, connect back to the computer, and verify that you've obtained the required voltage and current. \$\endgroup\$ – Adam Davis Jan 14 '14 at 1:10
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    \$\begingroup\$ Safer would be to cut the USB cable and do a simple resistance check between the red wire in the cable and one of the pins, and the black wire in the cable and one of the pins. Assuming your cable is USB spec compliant, it will follow the correct color code. \$\endgroup\$ – Adam Davis Jan 14 '14 at 1:16
  • \$\begingroup\$ Thanks The USB Micro B is P# 10118193-0001LF. You can find it in Digikey. I am lefting the pin 4 open. This is what I am doing: I connect the USB cable to my laptop, then I connect the USB micro B connector to the cable and I test the pin 1 (+5V) and 5 (0V) with my tester but I don´t get any voltage. The cable is all right because it is the same one I use to comunicate my cell phone with the computer and it works all right. Should this work? Must I try with another cable? I don´t want to cut the cable and connect only the red and black cable but, do you think I shoul do this? Thanks again \$\endgroup\$ – user35533 Jan 14 '14 at 14:00
  • \$\begingroup\$ I have just connect the connector to my cellphone wall charger and I reach the needed 5V. Unluckily, I need to reach the 5V connecting it to a USB port of my computer. What do you think that must be happening? \$\endgroup\$ – user35533 Jan 14 '14 at 21:42
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USB cables have 4 wires inside, normally black is GND and red is +5V and are at opposite sides of the connection e.g. 5V|D+|D-|GND probe with your multimeter to check which is which.

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  • \$\begingroup\$ Hello, the problem is that neither of them gives me 5V \$\endgroup\$ – user35533 Jan 14 '14 at 14:02
  • \$\begingroup\$ I don't know then, is the USB power coming from a wall wart or a USB port on your computer? \$\endgroup\$ – JMercer Jan 14 '14 at 21:00
  • \$\begingroup\$ I have just connect the connector to my cellphone wall charger and I reach the needed 5V. Unluckily, I need to reach the 5V connecting it to a USB port of my computer. What do you think that must be happening? \$\endgroup\$ – user35533 Jan 14 '14 at 21:42
  • \$\begingroup\$ I don't know if this is the case, but maybe the computer is cutting power because your device is drawing too high a current or maybe the computer doesn't power if the D+ and D- lines aren't connected? \$\endgroup\$ – JMercer Jan 14 '14 at 21:49
  • \$\begingroup\$ Test the output on the USB when it's plugged into the computer but not into your device \$\endgroup\$ – JMercer Jan 14 '14 at 21:49
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Attached is a clip of a schematic from a working product. Pin 1 is +5, Pin 5 is 0V. You can look up the datasheet for the connector (part number shown). Pins 2 and 3 are Data lines (D- and D+ respectively), which you didn't ask about.

Schematic image showing ZX62WRD-B-5PC

Pin 4 is used to select between host and client for OTG, and should be left open.

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  • \$\begingroup\$ This is what i am doing but I don´t get any voltage. Should I test the pins with the wall charger? \$\endgroup\$ – user35533 Jan 14 '14 at 14:35
  • \$\begingroup\$ Sure, give that a try. You could also try your computer after a reboot in case it has shut down the port power for some reason. \$\endgroup\$ – Spehro Pefhany Jan 14 '14 at 16:59
  • \$\begingroup\$ Hello, I have just connect the connector to my cellphone wall charger and I reach the needed 5V. Unluckily, I need to reach the 5V connecting it to a USB port. What do you think that must be happening? \$\endgroup\$ – user35533 Jan 14 '14 at 21:41
  • \$\begingroup\$ It was a problem with the USB cable. Please read my comments below. Thanks a lot for your help \$\endgroup\$ – user35533 Jan 14 '14 at 22:15
  • \$\begingroup\$ Just curious, why is the MH (metal hood?) connected to ground with a cap, instead of directly or with a resistor? \$\endgroup\$ – Paul Jul 16 at 5:04
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Spehro Pefhany and J. Mercer, Thank you all for your help. The problem was that the cable I was using doesn´t give 5v at the output. It gives only 0,3V. I couldn´t find the spec sheet but it has a label that says V8/V9 S/N: WT048000317 . I have just tried with 5 different cables and it worked all right with all of them. The fact that I am a beginer maked me ask the question in the forum but with your answers, you gave me confidence that I was doing everything all right. That really helped me to find the solution. Thank you all and keep like this. You are great!!!! Thanks again, Nicolas Cantera

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