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R-2R Resistor Network

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BobW

Active Member
I was looking at ordering a Bourns 4610X-R2R-103LF R-2R resistor network to make a simple D/A converter, but the specs left me puzzled.

Here is the datasheet:
http://www.bourns.com/docs/Product-Datasheets/R2R.pdf

On the left side of the first page, under the heading "Product Characteristics" standard tolerance is given as ±2%. That's all it says about tolerance anywhere in the document. It says nothing about variance between individual resistors within the network. I'm guessing that is the net tolerance of network, but not the variances of the individual resistors. I would assume that the network would still give a resolution of less than half the least significant bit, or else the network would be of no practical use. I'm still puzzled why they wouldn't give numbers for the resolution of the network. How would you interpret this?
 

AnalogKid

Well-Known Member
Most Helpful Member
In general, I've found that resistor network absolute accuracy is ok, but the relative tracking is much better. Some networks have a separate spec line for this, a tracking error percentage.

ak
 

BobW

Active Member
That's what I figured. I'm surprised how little information is provided on the Bourns datasheet. Anyway, I guess I'll find out shortly. I ordered a few of them, and they should be here tomorrow.
 

BobW

Active Member
They arrived today, and they work like a charm. I needed to get true D/A out from a PIC, and PWM isn't suitable for this application. I used a 74HC595 8 bit shift register with the R-2R network and linearity looks pretty good.
 

JonSea

Well-Known Member
Most Helpful Member
If memory serves, the error of the elements in a resistor network will be the same as the overall error.
 
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