Choosing an op amp

Thread Starter

edvard_m

Joined Dec 1, 2009
6
Hi everyone,

I have a 1mA DC current that I am going to run through a 100ohm resistor to convert to a voltage and send to input of an opamp. I need low noise so I can detect at least a 10uA change in the DC current. I searched digi-key and there are so many that seem to work for my application. Does anyone have any suggestions for specific surface mount parts to look into that are low noise with good dc characteristics? Also, I need it to run from a single voltage supply of 3V or less.

Thanks,
ed
 

SgtWookie

Joined Jul 17, 2007
22,230
Have a look at this one...
Datasheet: http://cds.linear.com/docs/Datasheet/20545fc.pdf
http://www.linear.com/pc/productDetail.jsp?navId=H0,C1,C1027,P2439
LTC2054 - Single/Dual Micropower Zero-Drift Operational Amplifiers
FEATURES
Supply Current 150μA (Max per Amplifier)
Guaranteed from –40°C to 85°C
Offset Voltage 3μV (Max, –40°C to 85°C)
Offset Voltage Drift 30nV/°C (Max, –40°C to 85°C)
Guaranteed Specifications from –55°C to 150°C (LTC2054MP)
Common Mode Input Range from V– to V+ – 0.5V
Output Swings Rail-to-Rail
Voltage Gain: 140dB (Typ)
PSRR and CMRR: 130dB (Typ)
Input Bias Current: 1pA (Typ, 25°C)
Noise: 1.6μVP-P (0.01Hz to 10Hz Typ)
Supply Operation:
2.7V to 6V (LTC2054/LTC2055)
2.7V to ±5.5V (LTC2054HV/LTC2055HV)
Low Profile (1mm) SOT-23, MS8 and 3mm × 3mm × 0.8mm DFN Packages
You really haven't given a lot of detail about your application, but this opamp has very low drift and only 3uV offset maximum over op temp range, low power, low noise; and it fits your 3v single-supply and SMT/SMD requirement as well.
 
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