SOT-23 breakout PCB

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parkview
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SOT-23 breakout PCB

Post by parkview » Wed Apr 28, 2021 5:37 pm

A SOT-23 footprint is used a lot in electronic printed circuit board (PCB) SMD layouts. They are quite small, around 1.5mm x 3mm long - excluding the metal pads. You can buy a huge range of MOSFETs, transistors and even diodes in that format. This board can be used for all of these, including N-MOS and P-MOS, NPN or PNP devices.

There have been times when I have wanted to test or check a SOT-23 based MOSFET on a breadboard, so that leaves me having to cut up a small piece of vero board and carefully solder the MOSFET into place:
MOSFET-vero.jpg
MOSFET-vero.jpg (33.21 KiB) Viewed 497 times
But it could all be easier if I had a small SOT-23 blank PCB that I could solder the device into place, so I created such a board:
SOT-23-PCB-front.jpg
SOT-23-PCB-front.jpg (9.95 KiB) Viewed 497 times

Only two resistors are usually needed, a low value gate resistor and a 10K to 100K ohm pull down resistor for N-MOS, or configured as a pull up for a P-MOS resistor. A transistor might use one or two resistors depending on the configuration being used. With horizontal pin headers for easy breadboard use, it will look something like this:
SOT-23-PCB-front.1.jpg
SOT-23-PCB-front.1.jpg (22.83 KiB) Viewed 497 times
On the back of the PCB, are pads for a gate based LED and a back-EMF protection diode that can be placed across the SOT-23 pads. This is a tiny PCB, so I will get a lot of these onto one PCB panel :D

parkview
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Location: Busselton
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Re: SOT-23 breakout PCB

Post by parkview » Sat May 29, 2021 2:22 pm

The SOT-23 Breakout PCB arrived the other day. I soldered up two AO3401 and two AO3400 SOT-23 MOSFETs onto some of the breakout PCB's. One thing I didn't take into account, is that I didn't leave enough 'white space' to carefully write the name of the MOSFET onto the PCB.
SOT-23-Breakout_Sml.jpg
SOT-23-Breakout_Sml.jpg (48.5 KiB) Viewed 457 times

These will work really well on a breadboard. The PCB is 1.6mm thick, at this magnification it looks so thick.

TimH
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Re: SOT-23 breakout PCB

Post by TimH » Fri Jun 18, 2021 2:07 pm

Nice - awesome little board, that ruler you gave me really helps put that photo in perspective :-)

parkview
Guru Maker
Posts: 522
Joined: Tue Jun 24, 2014 8:25 pm
Location: Busselton
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Re: SOT-23 breakout PCB

Post by parkview » Sun Jul 11, 2021 1:50 pm

This PCB has been superseded by a PCB that incorporates a DFN1006 and SOT-23 footprint breakout: viewtopic.php?f=9&t=2461#p3784 AND more importantly - space to write the name of MOSFET that's been soldered into place!

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