Precision, Dual-Channel, JFET Input
Rail-to-Rail Instrumentation Amplifier
AD8224
FUNCTIONAL BLOCK DIAGRAM
FEATURES
Two channels in a small 4 mm × 4 mm LFCSP
Low input currents
16 15 14 13
25 pA maximum input bias current
2 pA maximum input offset current
High CMRR
94 dB CMRR (minimum), G = 10
84 dB CMRR (minimum) to 10 kHz, G = 10
Excellent ac specifications and low power
1.5 MHz bandwidth (G = 1)
AD8224
1
2
3
4
12
11
10
9
–IN1
RG1
RG1
+IN1
–IN2
RG2
RG2
+IN2
5
6
7
8
14 nV/√Hz input noise (1 kHz)
Slew rate 2 V/μs
750 μA quiescent current per amplifier (maximum)
Versatility
Figure 1.
Rail-to-rail output
Table 1. In Amps and Difference Amplifiers by Category
Input voltage range to below negative supply rail
4 kV ESD protection
4.5 V to 36 V single supply
2.25 V to 18 V dual supply
Gain set with single resistor (G = 1 to 1000)
High
Perform. Cost
AD82201 AD85531 AD628
AD8221
AD8222
Low
High
Mil
Low
Digital
Gain
Voltage Grade Power
AD620 AD6271 AD82311
AD6231
AD629
AD621
AD524
AD526
AD624
AD8250
AD8251
AD85551
AD85561
AD85571
APPLICATIONS
Medical instrumentation
Precision data acquisition
Transducer interface
1 Rail-to-rail output.
Differential drive for high resolution input ADCs
Remote sensors
GENERAL DESCRIPTION
The AD8224 is the first single-supply junction field effect
transistor (JFET) input instrumentation amplifier available in
the space-saving 16-lead, 4 mm × 4 mm LFCSP. It requires the
same board area as a typical single instrumentation amplifier
yet doubles the channel density and offers a lower cost per
channel without compromising performance.
Designed to alleviate this problem, the AD8224 can operate on a
18 V dual supply, as well as on a single +5 V supply. The device’s
rail-to-rail output stage maximizes dynamic range on the low
voltage supplies common in portable applications. Its ability to run
on a single 5 V supply eliminates the need for higher voltage, dual
supplies. The AD8224 draws a maximum of 750 μA of quiescent
current per amplifier, making it ideal for battery-powered devices.
Designed to meet the needs of high performance, portable
instrumentation, the AD8224 has a minimum common-mode
rejection ratio (CMRR) of 78 dB at dc and a minimum CMRR
of 74 dB at 10 kHz for G = 1. Maximum input bias current is
25 pA and typically remains below 300 pA over the entire
industrial temperature range. Despite the JFET inputs, the
AD8224 typically has a noise corner of only 10 Hz.
In addition, the AD8224 can be configured as a single-channel,
differential output instrumentation amplifier. Differential
outputs provide high noise immunity, which can be useful when
the output signal must travel through a noisy environment, such
as with remote sensors. The configuration can also be used to
drive differential input ADCs.
With the proliferation of mixed-signal processing, the number of
power supplies required in each system has grown.
For a single-channel version, use the AD8220.
Rev. 0
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