Saturday, November 28, 2009

What are the different types of Resistor Networks


Had a page out on interfacebus showing a few different schematic diagrams of both Resistor Array and Resistor Networks in a 16 pin Dual In-line Package [DIP]. The page also linked to RC Networks in a 16-pin DIP, and a page which showed the Passive DIP components. Also have a page covering Derating Resistor Networks.

Anyway I added a new page to cover Resistor Networks in a 20-pin Leadless Chip Carrier [LLCC], or 20-pin LLCC Resistor Networks. I then added one to cover 16-pin LLCC Resistor Networks.  I think most of the text is all the same on each of the pages. All the schematics are the same, except for the pin out and the packages so why wouldn't the text be the same.

I just noticed that the dual-resistor termination package in a 16-pin LLCC case only has seven termination resistors, what bus uses just 7 bits of data? Same thing with the common-pin package which only has 15 resistors.

So now there's a page for 16-pin DIPs, a 16-pin LCC and a 20-pin LCC package each with three different styles of resistor interconnections.

Design hint. Resistor Networks are great because they save a lot of board space, but there are problems with these components.
First noise is easily passed from one resistor to the next because they are all in the same package.
Secondly, one resistor [in the package] my be located in the correct spot on the PWB, but in many cases all other traces need to be routed out of their way to reach the resistor package. Individual resistor packages can be placed in the exact location required, resistor networks can not. This may not matter in low speed systems but in high speed networks trace distance does matter.

Graphic; Resistor Array, 16-pin Lead-Less Chip Carrier, 8-resistors, no common connection.

1 comment:

Leroy said...

2/24/10 Looks like hits to pages relating to resistor networks are picking up a bit, it's about time.