Resistor packs on DOUT/DIN

[John_Swenson]

Having just spent the weekend building 4 DOUT boards and 2 DIN boards I'm greatly in favor of converting the current board design into using resistor packs rather than individual resistors. I know the parts are probably a little more expensive and somewhat harder to get, but putting in what seemed to be thousands of resistors was not fun! (not to mention blistering)

Any thoughts on this from others?

Thanks for considering it,

John S.

[Synapsys]

Hi,

I use resistor packs all the time. For DIN I use the bussed type that have a common connection to all resistors in the pack since the resistors are used as pull-ups. For DOUT I use the isolated type where each resistor in the pack is separate. I find that using resistor packs makes for a more compact PCB since the pins are on 2.54mm centers (the same as an IC). As far as cost, an 8 resistor pack is around $0.32 USD.

Since the 74HC165 chips on the DIN have four inputs on each side of the chip I use a five-pin resistor pack (4 resistors) one on each side of the chip. The 74HC595 chips on the DOUT have seven output pins on one side of the chip and one output on pin 15. For these I use two 8 pin packs (4 resistors each) on one side of the chip since routing pin 15 across is very easy.  :)