ADA4530-1 Datasheet, PDF (1/51 Pages) Analog Devices – Femtoampere Input Bias Current Electrometer Amplifier

Data Sheet
Femtoampere Input Bias Current
Electrometer Amplifier
ADA4530-1
FEATURES
Low input bias current
±20 fA maximum at TA = 25°C (guaranteed at production test)
± 20 fA maximum at −40°C < TA < +85°C
± 250 fA maximum at −40°C < TA < +125°C (guaranteed at
production test)
Low offset voltage: 50 μV maximum over specified CMRR range
Offset drift: 0.13 μV/°C typical, 0.5 μV/°C maximum
Integrated guard buffer with 100 μV maximum offset
Low voltage noise density: 14 nV/√Hz at 10 kHz
Wide bandwidth: 2 MHz unity-gain crossover
Supply voltage: 4.5 V to 16 V (±2.25 V to ±8 V)
Operating temperature: −40°C to +125°C
APPLICATIONS
Laboratory and analytical instrumentation:
spectrophotometers, chromatographs, mass
spectrometers, and potentiostatic and amperostatic
coulometry
Instrumentation: picoammeters and coulombmeters
Transimpedance amplifier (TIA) for photodiodes, ion
chambers, and working electrode measurements
High impedance buffering for chemical sensors and
capacitive sensors
GENERAL DESCRIPTION
The ADA4530-1 is a femtoampere (10^−15 A) level input bias
current operational amplifier suitable for use as an electrometer
that also includes an integrated guard buffer. It has an operating
voltage range of 4.5 V to 16 V enabling it to operate in conven-
tional 5 V and 10 V single supply systems as well as ±2.5 V and
±5 V dual supply systems.
It provides ultralow input bias currents that are production
tested at temperature to ensure the device meets its perfor-
mance goals in user systems. The integrated guard buffer is
provided to isolate the input pins from leakage in the printed
circuit board (PCB), minimize board component count, and
enable ease of system design. The ADA4530-1 is available in an
industry-standard surface-mount 8-lead SOIC package with a
unique pinout optimized to prevent signals from coupling
between the sensitive input pins, the power supplies, and the
output pin while enabling easy routing of the guard ring traces.
The ADA4530-1 also offers low offset voltage, low offset drift,
and low voltage and current noise needed for the types of
applications that require such low leakages. To maximize the
dynamic range of the system, the ADA4530-1 has a rail-to-rail
PIN CONNECTION DIAGRAM
ADA4530-1
+IN 1
GRD 2
IC 3
V– 4
8 –IN
7 GRD
6 OUT
5 V+
NOTES
1. IC = INTERNAL CONNECTION. THIS
PIN MUST BE CONNECTED TO V–
OR LEFT UNCONNECTED.
Figure 1.
output stage that can typically drive to within 30 mV of the
supply rails under a 10 kΩ load.
The ADA4530-1 operates over the −40°C to +125°C industrial
temperature range and is available in an 8-lead SOIC package.
1000
100
V_SY = 10V
V_CM = V_SY/2
RH < 10%
–40°C TO +125°C LIMIT
–40°C TO +85°C LIMIT
10
1
0.1
II_BB+–
0.01
0.001
0
10 20 30 40 50 60 70 80 90 100 110 120 130
TEMPERATURE (°C)
Figure 2. Input Bias Current (IB) vs. Temperature, VSY = 10 V
Rev. A
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