# Help identify this component

What is this component? It's between two ICs, probably on a communication bus. One is a microcontroller and the other is some sort of memory. It's as small as an smd capacitor or resistor.

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 What's the pin 1 indication for? They're symmetrical. – Federico Russo Jul 24 '11 at 11:44

It's a (hand-soldered) quad resistor array. The resistors' value is indicated the same way it's done on single resistors: the first two digits for significant digits, and the third for the multiplier (power of 10). So 220 should be read as $22 \times 10^0 = 22\Omega$.

SMT resistor arrays exist in dual, quad and octal versions. They're often used on microcontroller buses, either in series with for example data lines, or as pull-ups for the address bus. Arrays are space-saving and cheaper than single parts. (Placing a part is several times more expensive than the cost of the part itself, so placing 1 array costs only 1/4 of placing 4 single resistors.) The quads are most often used, even for wider buses because they're easier to layout on complex boards. For the pull-ups there are resistor networks with one side of all resistors connected to a single pin.

Just like single resistors the arrays exist in different sizes, where the size is indicated in tens of mils (hundredths of inches). So a 0804 package is 80mils x 40mils (2mm x 1mm). Convex and concave pinouts exist.

There are also capacitor networks, as well as combined resistor-capacitor networks.
Manufacturers include Vishay, Yageo and Rohm.

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It's a quad 22.0 Ohm resistor........

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tricky. I've never seen quad resistors before. tnx – csadam Jan 24 '11 at 19:08
They are used alot on motherboards in our computers. There are also octal ones. – BarsMonster Jan 24 '11 at 19:14
Specifically, it's an isolated resistor array. Some resistors that appear similar can be bussed to provide X (usually 9 or 15) pull-ups in a small space with a minimal number of vias. – Nick T Jan 24 '11 at 20:33

Resistor network. A chip that contains resistors in a latter or isolated configuration.

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