DOUT, LEDs, and Heat

[m00dawg]

I am working on creating a daughter-board for my LED Matrix which will include the shift-registers for the buttons and LEDs. But I'm having trouble getting things to work well if I put my SMD shift registers on the bottom of the board. I wanted to do this so that the SRs would not be sandwiched between the LED matrix board itself and the daughter-board, mostly due to worrying about heat.

Would heat be that much of a concern in this case? And, if so, could I just use transistors to avoid that problem?

I was thinking no since some heat will be transferred to the ground (and, if I have it, power) plane and it's still small levels of current. But wanted to make sure before I called my design good and ready for prototyping :)

[Janis1279]

Hi,

The SR's electrical parameters for the Dip16 and So16 cases are look very similar. Only a difference I found is in a Note1 at a page 8 from the attachment file.

Regards,

Janis

74HC595.pdf

[m00dawg]

I have a similar spec sheet (I think from TI) and yeah it's very similar. I noticed the range is -40 to 125C which I would obviously be within. Didn't know how that accounted for airflow but I'm guessing since I can't find it in the spec sheets that it's probably a non-issue.

[ilmenator]

Apart from voltage regulators and SID chips I would not worry about any components in the MIDIbox world being overly sensitive to (lack of) heat dissipation. Placing shift registers between two layers of PCBs (that are about a cm or so apart in any case) should be no problem at all.

[m00dawg]

Awesome! Thank you both for the advice!