What is the Common mode voltage range of ADA4522-2 ?

Question

Hi, 
 I would like to know the common mode voltage range of ADA4522-2. I am using this as a buffer. The supply voltage to the Op-Amp is ±5 V and my input would be near to 5V( assume 4.9V). What can be my possible output value.? 
 Thanks in advance.

FormerMember · Accepted Answer

C4 is BAD!!! Remove it!! If the op amp is a perfect voltage source, then the cap does nothing. 
 But op amps have a finite output impedance, so you create an R-C low pass which 
 gives phase shift and reduces stability, leading to oscillations. 
 Harry)

FormerMember · Answer

I would guess that the majority of your drift over temp comes from the resistors, especially R3. Is it a precision 
 resistor with a guaranteed tempco of less than 5 ppm/C?? 
 Harry

FormerMember · Answer

Before 1975, most op amps ran on +/-15V, and the IVR was +/-12V, or +/-10V or whatever. 
 So if you ran it on ground and +30V, the IVR was 3V to 27V. National invented the LM324, 
 which had a PNP input stage, so if you ran it on ground and +5V, the IVR was ground to 3.5V. 
 So the official definition of single supply is an op amp where the IVR includes the V- rail. 
 Having said that, all op amps will run on a single supply, but you have to watch out for the IVR. 
 Harry

FormerMember · Answer

For case 1, is the output voltage higher or lower?? (I'm guessing higher) 
 What is the input impedance of your meter? 
 Have you tried a different brand of meter? 
 What is the source impedance of the node you are measuring? 
 Harry

FormerMember · Answer

Don't know what your schematic is, but if you have a current source driving a 120k resistor, 
 and you put a 1Meg DVM across the 120k, the current source has a high output impedance 
 and supplies a fixed current, so some of the current goes through the 1Meg and you get a 
 lower voltage across the 120k. 
 Harry

EZAdministrator · Answer

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Emman.A · Answer

Hi Ashok, 
 Rail to rail output amplifier means that output of the amplifier can go almost equal to the supply rails (of course there will be few millivolts drops to the Vce or Vds of the output transistor). But this is not necessarily mean that this kind of amplifier is also a rail to rail input. 
 It is useful in achieving the maximum output signal swing with low supply voltage which results in increase of dynamic range. 
 Rail to rail input, on the other hand, means that the input can span the entire supply voltage range. 
 You can easily check it on the spec table and look for the input voltage range. 
 This is for the ADA4522:You can see that the input voltage needs 1.5V headroom from the positive supply rail. 
 
 This is for the AD8638: it need 2V headroom from the supply rail. This is also the reason why you only see 3V on the spice model. 
 
 Since your circuit is a buffer and your input voltage can reach up to the same level as your positive supply rail, then you may need an amplifier that is rail to rail input and rail to rail output. . 
 Now there are amplifiers that are both rail to rail input and rail to rail output like the ADA4091, ADA4084, etc. 
 But for the zero drift amplifier portfolio which are well known for ultra low offset and drift, only the ADA4528 is rail to rail input and rail to rail output amplifier but it can only go supply voltage of up to 5.5V. 
 There are also only 3 Zero Drift amplifier that can accommodate supply voltage of =>+/-5V but there are not rail to rail input. 
 What is your target accuracy specs in terms of offset and drift? 
 Also what is your minimum input voltage? 
 Are you expecting negative input voltage? 
 Because if not, then you can probably use the ADA4528 with V+ tied to 5V and V- tied to ground. 
 I hope this helps. 
 Best regards, 
 Emman

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What is the Common mode voltage range of ADA4522-2 ?