AD8251_15 Datasheet, PDF (1/24 Pages) Analog Devices – Programmable Gain Instrumentation Amplifier

10 MHz, 20 V/μs, G = 1, 2, 4, 8 iCMOS
Programmable Gain Instrumentation Amplifier
AD8251
FEATURES
Small package: 10-lead MSOP
Programmable gains: 1, 2, 4, 8
Digital or pin-programmable gain setting
Wide supply: ±5 V to ±15 V
Excellent dc performance
High CMRR: 98 dB (minimum), G = 8
Low gain drift: 10 ppm/°C (maximum)
Low offset drift: 1.8 μV/°C (maximum), G = 8
Excellent ac performance
Fast settling time: 785 ns to 0.001% (maximum)
High slew rate: 20 V/μs (minimum)
Low distortion: −110 dB THD at 1 kHz, 10 V swing
High CMRR over frequency: 80 dB to 50 kHz (minimum)
Low noise: 18 nV/√Hz, G = 8 (maximum)
Low power: 4.1 mA
APPLICATIONS
Data acquisition
Biomedical analysis
Test and measurement
GENERAL DESCRIPTION
The AD8251 is an instrumentation amplifier with digitally
programmable gains that has GΩ input impedance, low output
noise, and low distortion, making it suitable for interfacing with
sensors and driving high sample rate analog-to-digital converters
(ADCs). It has a high bandwidth of 10 MHz, low THD of −110 dB,
and fast settling time of 785 ns (maximum) to 0.001%. Offset
drift and gain drift are guaranteed to 1.8 μV/°C and 10 ppm/°C,
respectively, for G = 8. In addition to its wide input common
voltage range, it boasts a high common-mode rejection of 80 dB
at G = 1 from dc to 50 kHz. The combination of precision dc
performance coupled with high speed capabilities makes the
AD8251 an excellent candidate for data acquisition. Furthermore,
this monolithic solution simplifies design and manufacturing
and boosts performance of instrumentation by maintaining a
tight match of internal resistors and amplifiers.
The AD8251 user interface consists of a parallel port that allows
users to set the gain in one of two ways (see Figure 1). A 2-bit word
sent via a bus can be latched using the WR input. An alternative is
to use the transparent gain mode where the state of the logic
levels at the gain port determines the gain.
FUNCTIONAL BLOCK DIAGRAM
DGND WR A1 A0
2
6
5
4
–IN 1
LOGIC
7 OUT
+IN 10
8
+V_S
25
AD8251
3
9
–V_S
REF
Figure 1.
20
G=8
15
G=4
10
G=2
5
G=1
0
–5
–10
1k
10k
100k
1M
10M
FREQUENCY (Hz)
Figure 2. Gain vs. Frequency
100M
Table 1. Instrumentation Amplifiers by Category
General
Purpose
Mil
Zero Drift Grade
Low
Power
High Speed
PGA
AD8220¹
AD8221
AD8222
AD8224¹
AD8228
AD8231¹
AD8553¹
AD8555¹
AD8556¹
AD8557¹
AD620
AD621
AD524
AD526
AD624
AD627¹
AD623¹
AD8223¹
AD8250
AD8251
AD8253
1 _{Rail-to-rail output.}
The AD8251 is available in a 10-lead MSOP package and is
specified over the −40°C to +85°C temperature range, making it
an excellent solution for applications where size and packing
density are important considerations.
Rev. B
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