AD8224_15 Datasheet, PDF (1/28 Pages) Analog Devices – Precision, Dual-Channel, JFET Input, Rail-to-Rail Instrumentation Amplifier

Data Sheet
Precision, Dual-Channel, JFET Input,
Rail-to-Rail Instrumentation Amplifier
AD8224
FEATURES
Two channels in a small 4 mm × 4 mm LFCSP
Custom LFCSP package with hidden paddle
Permits routing and vias underneath package
Allows full bias current performance
Low input currents
10 pA maximum input bias current (B Grade)
0.6 pA maximum input offset current (B Grade)
High CMRR
100 dB CMRR (minimum), G = 10 (B Grade)
90 dB CMRR (minimum) to 10 kHz, G = 10 (B Grade)
Excellent ac specifications and low power
1.5 MHz bandwidth (G = 1)
14 nV/√Hz input noise (1 kHz)
Slew rate: 2 V/μs
750 μA quiescent current per amplifier
Versatility
Rail-to-rail output
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)
APPLICATIONS
Medical instrumentation
Precision data acquisition
Transducer interfaces
Differential drives for high resolution input ADCs
Remote sensors
GENERAL DESCRIPTION
The AD8224 is the first single-supply, 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 meet the needs of high performance, portable
instrumentation, the AD8224 has a minimum common-mode
rejection ratio (CMRR) of 86 dB at dc and a minimum CMRR
of 80 dB at 10 kHz for G = 1. Maximum input bias current is
10 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.
With the proliferation of mixed-signal processing, the number
of power supplies required in each system has grown. Designed
Rev. C
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FUNCTIONAL BLOCK DIAGRAM
16 15 14 13
AD8224
–IN1 1
R_G1 2
R_G1 3
+IN1 4
12 –IN2
11 R_G2
10 R_G2
9 +IN2
5 678
Figure 1.
Table 1. In Amps and Difference Amplifiers by Category
High
Low
Perform Cost
High
Mil
Low
Digital
Voltage Grade Power Gain
AD8220¹ AD8553¹ AD628
AD8221 AD623¹ AD629
AD620 AD627¹ AD8231¹
AD621
AD8250
AD8222
AD524
AD8251
AD526
AD624
AD8555¹
AD8556¹
AD8557¹
1 _{Rail-to-rail output.}
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 750 μA of quiescent current per
amplifier, making it ideal for battery powered devices.
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. For a single-channel version, use
the AD8220.
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