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Hello i have what looks to be a PNP transistor.The marking code on it is U3W with the numbers 65 rotated 90 degrees next to U3W.Its a Sot-23-3 package,refer to image of schematic of how its connected.

Pin A and Pin B are from a RS-485 transceiver,and another note the A,B pins are used to send DMX512 data across it.

Firstly could this be a transistor based on how its connected?If it is do you happen to know the part#,or company,etc?Any input is appreciated thanks.enter image description here

http://www.ti.com/lit/ds/symlink/sn65176b.pdf

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closed as unclear what you're asking by Voltage Spike, PeterJ, Dmitry Grigoryev, Daniel Grillo, winny Aug 8 '17 at 7:40

Please clarify your specific problem or add additional details to highlight exactly what you need. As it's currently written, it’s hard to tell exactly what you're asking. See the How to Ask page for help clarifying this question. If this question can be reworded to fit the rules in the help center, please edit the question.

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    \$\begingroup\$ Your schematic says it's NPN, but your text says it's PNP. Which is it? \$\endgroup\$ – ThreePhaseEel Aug 2 '17 at 2:21
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    \$\begingroup\$ You're sure it's not a dual diode, used for over and/or undervoltage or ESD protection? \$\endgroup\$ – The Photon Aug 2 '17 at 2:30
  • \$\begingroup\$ Yeah, I was thinking dual TVS diode myself...but if it's reading like a PNP, then it's the wrong way 'round to be a dual TVS... \$\endgroup\$ – ThreePhaseEel Aug 2 '17 at 2:36
  • \$\begingroup\$ Not that a simple common-cathode dual (zener/tvs/...) diode would work for RS-485, but there are lots of different kinds of protection parts out there. \$\endgroup\$ – The Photon Aug 2 '17 at 2:43
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    \$\begingroup\$ @ThreePhaseEel It is a PNP. \$\endgroup\$ – user155600 Aug 2 '17 at 3:24
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It seems likely the part is some kind of ESD and/or over-voltage protection device.

For example, something like CDSOT23-SM712, which has asymmetric clamping voltage that seem to be pretty well matched to RS-485 (which can go to +12 V positive but only -7 V negative).

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  • \$\begingroup\$ FWIW, WU3 rather than U3W would likely be Nexperia's PESD15VS2UT but this wouldn't deal well with negative signal voltages. \$\endgroup\$ – The Photon Aug 2 '17 at 3:02

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