differences between shunt and series voltage references?

Aside from series vs. shunt, some ADCs are quite demanding as far as the reference output impedance goes.

This is a pretty accurate (0.05%) and stable (and low current) reference for the price:

Best regards, Spehro Pefhany

--
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Yes.

Does one have a major advantage over the other? Thanks for your

You have to compare the specs for noise and disturbance rejection. The series reference often uses less current than a shunt reference fed by just a resistor, if the raw voltage varys over a wide range.

Look here: Understanding Voltage-Reference Topologies and Specifications [

]

--
Guy Macon

Just to add another option...

I also like the National LM4120 for A-D references. I am using this as a reference for an existing A-D subsystem (not high speed, I must admit

- system voltage monitoring in this application).

I am using the LM4120AIM5-4.1 which has the following specs:

180mV dropout at 1mA (worst case, typical = 120mV) +/-5mA sink OR source 50ppm tempco Output noise voltage 20uV p-p 0.1Hz - 10Hz, 36uV p-p 10Hz - 10kHz Zo < 1 ohm for F < 10kHz ( at Iout = 1mA)

Comes in a nice SOT23-5 package.

Cheers

PeteS

I strongly suggest you look for *any* other brand; Maxim has the bad habit of advertising vaporware.

But the dropout voltage is so high, it cannot be fed from the +5V rail, here is a brand new reference REF3240

it needs only 100mV for an output current of 8mA, and just 1mV if the current is 1uA.

--
ciao Ban
Bordighera, Italy

Robert Baer wrote in news:NeqAe.6294$ snipped-for-privacy@newsread1.news.pas.earthlink.net:

Do you mean that they advertise alot of products that they never bring to market? I noticed they had a couple really nice SOT-23 V-regs - and then I realized that I couldn't find a distributor for *any* of the accurate ones. I also noticed they don't have samples available for these parts - so it seems to me that any parts that they have samples available for available... Thus I was lookin at the Maxim MAX6126:

.06% initial accuracy and it comes in a 8-uMAX package. (it says .02% on the above page but the 4.096 8-uMAX part is .06% if you look at pg. 16 of its datasheet) It does need a couple external components though (some small capacitors). It also seems to be available as a sample - though I couldn't find any distributor that stocked it. This is not a big deal as a total of

6 of these units will be made. I have made a sample request of this part - I guess I'll have to see if it actually comes.

Does that look like a good choice?

-Michael

Guy Macon wrote in news: snipped-for-privacy@corp.supernews.com:

Thanks - that was very helpful. I had been looking for something like that and just couldn't find it for some odd reason.

-Michael

I wanted to emphasize this. I've had to follow a reference with an op-amp.

Jon

Maxim does not have the best reputation for delivering on their 'products', especially in their reference stuff.

Even though they have claimed to me in the past that they have 'changed their ways' and will ship even if you don't want to buy 100k units of something, I have found their delivery very spotty. That can be a big problem if your system fundamentally relied on the function of the device you want from them, and they blithely quote 8-14 weeks lead time, when their reps etc. have promised there is sufficient stock on hand for the build you wanted to schedule in 3 weeks.

I always try and find an alternative (or multiply sourced) part when I see Maxim on the datasheet / suggested list.

Cheers

PeteS

If you do not mind waiting for a long time or possibly forever...