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Consider a 20-pin DIP IC with 2 rows, 10 pins in each row. For example, the Texas Instrument MSP430G2452 microcontroller. The measured distance between these two rows is just over 9 mm. On page 62 of the datasheet for this microcontroller, it reads a maximum distance of " 10.92 mm. " It does not state any other distance between the two rows except this maximum number.

At the same time, when searching through the Mouser website for a DIP socket, the only row spacing close to that number is "10.16 mm," but this is for a "22 position" DIP / SIP socket. How do I interpret this ? Does this information mean or imply that I should bend the pins of one of the rows of the microcontroller in order to make it fit the DIP socket ? Is this common practice ? Is this safe ?

Also, is it good practice to use a socket with the same amount of holes as the microcontroller, or does it not matter how many holes the DIP socket has as long as it has at least the same number of holes as there are pins on the microcontroller ? For that matter, will a difference between pin number of the microcontroller and hole number of the socket affect both the setup and functioning of the microcontroller ? Does the number of positions of a DIP socket need to match the pin count of an IC ??

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DIP packages are supplied with the leads spread beyond the proper spacing for footprints or sockets. The lead spacing should be 0.3" (7.62mm) for that package.

They are intended to be slightly compressed or formed before insertion. Both sides equally. This would be done by a machine in production (the machine would grab the part on the outside of the leads and compress it while holding it). By hand you can just push each side carefully (eg. against a sturdy antistatic mat) to form the leads. It will take a bit of practice to go just far enough.

There are tools, including motor-driven automated ones, that did the forming too, especially from back when DIP packages were more commonly used in production.

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While you can use a socket with (say) 24 or 28 pins and 0.3" lead spacing for that microcontroller, it's not good practice unless there's a good reason (such as upward compatibility) since it increases the chances of error occurring. Some of such errors may cause permanent damage to the MCU or possibly something else on the board.

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  • \$\begingroup\$ thanks for the post. wow, my logic was reversed. from what I understand from what you wrote and looking again at the Mouser site, I do see that there is a 20 position DIP socket with a row spacing of 7.62 mm. As you probably already noticed, I initially thought that I should widen the distance between the IC rows, but if I am following what you said I should actually reduce the distance between the rows with the intention of using the 20 position DIP socket. so to be sure, i should compress the rows a little and ONLY use the 20 position DIP socket. is that correct ? \$\endgroup\$ Commented Feb 18, 2024 at 4:11
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    \$\begingroup\$ That is correct. \$\endgroup\$ Commented Feb 18, 2024 at 4:13
  • \$\begingroup\$ If you use a socket that is too big you can insert the chip in the wrong position. To avoid that just buy the right size. But if you are prototyping and dont have the exact right size you can consider using the bigger size if you happen to have it and not the proper size... \$\endgroup\$ Commented Feb 24, 2024 at 1:59
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DIP ICs are normally supplied with the pins spread slightly. When the rows of pins are squeezed in to be parallel, they should be 0.4 inch (10.16 mm) apart, and will fit the socket you describe. We would normally use a socket with the same number of contacts as the part we want to put in it.

If you have a 20 pin IC and can only find 22 or 24 position sockets, you may use the larger sockets, but have to remember which contacts are unused, and not count those contacts when determining pin numbers for wiring the socket. You could cut off the unneeded contacts to avoid confusion.

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  • \$\begingroup\$ thanks for the post. i think the above answer from Spehro nailed it. also, just as clarification for future readers. remember, i wrote that the measured distance between the IC rows are just above 9mm. so squeezing them IN would not make them 10.16 mm apart. but i think you probably meant to write what Spehro wrote because you are in the right direction. i appreciate your effort though. \$\endgroup\$ Commented Feb 18, 2024 at 4:22
  • \$\begingroup\$ I suggested 0.4" (10.16mm) because you mentioned that the datasheet showed 10.92 mm - but I was worried about that because I don't recall seeing and DIP parts 0.4 wide - they are either 0.3 or 0.6", so I'll go with Spehro's answer. \$\endgroup\$ Commented Feb 18, 2024 at 5:07

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