AD8250-EVALZ [ADI]

10 MHz, 20 V/μs, G = 1, 2, 5, 10 iCMOS Programmable Gain Instrumentation Amplifier;
AD8250-EVALZ
型号: AD8250-EVALZ
厂家: ADI    ADI
描述:

10 MHz, 20 V/μs, G = 1, 2, 5, 10 iCMOS Programmable Gain Instrumentation Amplifier

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10 MHz, 20 V/μs, G = 1, 2, 5, 10 iCMOS  
Programmable Gain Instrumentation Amplifier  
Data Sheet  
AD8250  
FEATURES  
FUNCTIONAL BLOCK DIAGRAM  
DGND WR  
A1  
5
A0  
4
Small package: 10-lead MSOP  
Programmable gains: 1, 2, 5, 10  
Digital or pin-programmable gain setting  
Wide supply: 5 V to 15 V  
2
6
LOGIC  
1
–IN  
Excellent dc performance  
High CMRR 98 dB (minimum), G = 10  
Low gain drift: 10 ppm/°C (maximum)  
Low offset drift: 1.7 μV/°C (maximum), G = 10  
Excellent ac performance  
7
OUT  
10  
+IN  
Fast settling time: 615 ns to 0.001% (maximum)  
High slew rate: 20 V/µs (minimum)  
Low distortion: −110 dB THD at 1 kHz  
High CMRR over frequency: 80 dB to 50 kHz (minimum)  
Low noise: 18 nV/√Hz, G = 10 (maximum)  
Low power: 4.1 mA  
AD8250  
8
3
–V  
9
+V  
REF  
S
S
Figure 1.  
25  
20  
15  
10  
5
G = 10  
G = 5  
APPLICATIONS  
Data acquisition  
Biomedical analysis  
Test and measurement  
G = 2  
G = 1  
GENERAL DESCRIPTION  
0
The AD8250 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 615 ns (maximum) to 0.001%. Offset  
drift and gain drift are guaranteed to 1.7 μV/°C and 10 ppm/°C,  
respectively, for G = 10. 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  
AD8250 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.  
–5  
–10  
1k  
10k  
100k  
1M  
10M  
100M  
FREQUENCY (Hz)  
Figure 2. Gain vs. Frequency  
Table 1. Instrumentation Amplifiers by Category  
General  
Purpose  
AD82201  
AD8221  
AD8222  
AD82241  
AD8228  
Mil  
Grade  
Low  
Power  
AD6271  
AD6231  
AD82231  
High Speed  
PGA  
Zero Drift  
AD82311  
AD85531  
AD85551  
AD85561  
AD85571  
AD620  
AD621  
AD524  
AD526  
AD624  
AD8250  
AD8251  
AD8253  
1
Rail-to-rail output.  
The AD8250 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  
The AD8250 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.  
sent via a bus can be latched using the  
input. An alternative is  
WR  
to use the transparent gain mode where the state of the logic levels  
at the gain port determines the gain.  
Rev. C  
Document Feedback  
Information furnished by Analog Devices is believed to be accurate and reliable. However, no  
responsibility is assumed by Analog Devices for its use, nor for any infringements of patents or other  
rightsof third parties that may result fromits use. Specifications subject to change without notice. No  
license is granted by implication or otherwise under any patent or patent rights of Analog Devices.  
Trademarks andregisteredtrademarks are the property of their respective owners.  
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.  
Tel: 781.329.4700 ©2007–2013 Analog Devices, Inc. All rights reserved.  
Technical Support  
www.analog.com  
 
 
 
 
 
AD8250* Product Page Quick Links  
Last Content Update: 11/01/2016  
Comparable Parts  
Reference Materials  
View a parametric search of comparable parts  
Technical Articles  
• Auto-Zero Amplifiers  
Evaluation Kits  
• High-performance Adder Uses Instrumentation Amplifiers  
• AD8250 Evaluation Board  
Design Resources  
• AD8250 Material Declaration  
• PCN-PDN Information  
• Quality And Reliability  
• Symbols and Footprints  
Documentation  
Application Notes  
• AN-1401: Instrumentation Amplifier Common-Mode  
Range: The Diamond Plot  
Data Sheet  
AD8250: 10 MHz, 20 V/μs, G = 1, 2, 5, 10 iCMOS  
Programmable Gain Instrumentation Amplifier Data Sheet  
Discussions  
View all AD8250 EngineerZone Discussions  
Technical Books  
• A Designer's Guide to Instrumentation Amplifiers, 3rd  
Edition, 2006  
Sample and Buy  
Visit the product page to see pricing options  
Tools and Simulations  
• AD8250 SPICE Macro Model  
Technical Support  
Submit a technical question or find your regional support  
number  
* This page was dynamically generated by Analog Devices, Inc. and inserted into this data sheet. Note: Dynamic changes to  
the content on this page does not constitute a change to the revision number of the product data sheet. This content may be  
frequently modified.  
AD8250  
Data Sheet  
TABLE OF CONTENTS  
Features .............................................................................................. 1  
Input Bias Current Return Path ............................................... 17  
Input Protection ......................................................................... 17  
Reference Terminal .................................................................... 18  
Common-Mode Input Voltage Range..................................... 18  
Layout .......................................................................................... 18  
RF Interference ........................................................................... 19  
Driving an ADC ......................................................................... 19  
Applications..................................................................................... 20  
Differential Output .................................................................... 20  
Setting Gains with a Microcontroller ...................................... 20  
Data Acquisition......................................................................... 21  
Outline Dimensions ....................................................................... 22  
Ordering Guide .......................................................................... 22  
Applications....................................................................................... 1  
General Description ......................................................................... 1  
Functional Block Diagram .............................................................. 1  
Revision History ............................................................................... 2  
Specifications..................................................................................... 3  
Timing Diagram ........................................................................... 5  
Absolute Maximum Ratings............................................................ 6  
Maximum Power Dissipation ..................................................... 6  
ESD Caution.................................................................................. 6  
Pin Configuration and Function Descriptions............................. 7  
Typical Performance Characteristics ............................................. 8  
Theory of Operation ...................................................................... 15  
Gain Selection............................................................................. 15  
Power Supply Regulation and Bypassing ................................ 17  
REVISION HISTORY  
Changes to Table 3.............................................................................6  
Added Figure 17; Renumbered Sequentially .................................9  
Changes to Figure 23...................................................................... 10  
Changes to Figure 24 to Figure 26................................................ 11  
Added Figure 29 ............................................................................. 11  
Changes to Figure 31...................................................................... 12  
Deleted Figure 43 to Figure 46; Renumbered Sequentially ...... 14  
Inserted Figure 45 and Figure 46.................................................. 14  
Changes to Timing for Latched Gain Mode Section ................. 16  
Changes to Layout Section and Coupling Noise Section.......... 18  
Changes to Figure 59...................................................................... 21  
5/13—Rev. B to Rev. C  
Changed 49.9 Ω to 100 Ω in Driving an ADC Section and  
Figure 55 .......................................................................................... 19  
11/10—Rev. A to Rev. B  
Changes to Voltage Offset, Offset RTI VOS, Average  
Temperature Coefficient Parameter in Table 2............................. 3  
Updated Outline Dimensions....................................................... 22  
5/08—Rev. 0 to Rev. A  
Changes to Table 1............................................................................ 1  
Changes to Table 2 ............................................................................ 3  
1/07—Revision 0: Initial Version  
Rev. C | Page 2 of 24  
 
Data Sheet  
AD8250  
SPECIFICATIONS  
+VS = 15 V, VS = −15 V, VREF = 0 V @ TA = 25°C, G = 1, RL = 2 kΩ, unless otherwise noted.  
Table 2.  
Parameter  
Conditions  
Min  
Typ  
Max  
Unit  
COMMON-MODE REJECTION RATIO (CMRR)  
CMRR to 60 Hz with 1 kΩ Source Imbalance  
+IN = −IN = −10 V to +10 V  
G = 1  
G = 2  
G = 5  
G = 10  
80  
86  
94  
98  
98  
dB  
dB  
dB  
dB  
104  
110  
110  
CMRR to 50 kHz  
+IN = −IN = −10 V to +10 V  
G = 1  
G = 2  
G = 5  
G = 10  
80  
86  
90  
90  
dB  
dB  
dB  
dB  
NOISE  
Voltage Noise, 1 kHz, RTI  
G = 1  
G = 2  
G = 5  
G = 10  
40  
27  
21  
18  
nV/√Hz  
nV/√Hz  
nV/√Hz  
nV/√Hz  
0.1 Hz to 10 Hz, RTI  
G = 1  
G = 2  
G = 5  
G = 10  
2.5  
2.5  
1.5  
1.0  
μV p-p  
μV p-p  
μV p-p  
μV p-p  
pA/√Hz  
pA p-p  
Current Noise, 1 kHz  
Current Noise, 0.1 Hz to 10 Hz  
VOLTAGE OFFSET  
Offset RTI VOS  
5
60  
G = 1, 2, 5, 10  
(70 + 200/G)  
(200 + 600/G) μV  
(260 + 900/G) μV  
(1.2 + 5/G)  
(6 + 20/G)  
Over Temperature  
Average Temperature Coefficient  
Offset Referred to the Input vs. Supply (PSR)  
INPUT CURRENT  
Input Bias Current  
Over Temperature  
Average Temperature Coefficient  
Input Offset Current  
Over Temperature  
Average Temperature Coefficient  
DYNAMIC RESPONSE  
Small Signal −3 dB Bandwidth  
G = 1  
T = −40°C to +85°C  
T = −40°C to +85°C  
VS = 5 V to 15 V  
(90 + 300/G)  
(0.6 + 1.5/G)  
(2 + 7/G)  
μV/°C  
μV/V  
5
5
30  
40  
400  
30  
30  
nA  
nA  
pA/°C  
nA  
nA  
T = −40°C to +85°C  
T = −40°C to +85°C  
T = −40°C to +85°C  
T = −40°C to +85°C  
160  
pA/°C  
10  
10  
10  
3
MHz  
MHz  
MHz  
MHz  
G = 2  
G = 5  
G = 10  
Settling Time 0.01%  
G = 1  
G = 2  
G = 5  
G = 10  
ΔOUT = 10 V step  
585  
605  
605  
648  
ns  
ns  
ns  
ns  
Rev. C | Page 3 of 24  
 
 
AD8250  
Data Sheet  
Parameter  
Conditions  
Min  
Typ  
Max  
Unit  
Settling Time 0.001%  
ΔOUT = 10 V step  
G = 1  
G = 2  
G = 5  
G = 10  
615  
635  
635  
685  
ns  
ns  
ns  
ns  
Slew Rate  
G = 1  
G = 2  
G = 5  
G = 10  
20  
25  
25  
25  
V/μs  
V/μs  
V/μs  
V/μs  
dB  
Total Harmonic Distortion  
f = 1 kHz, RL = 10 kΩ, 10 V,  
G = 1, 10 Hz to 22 kHz  
band-pass filter  
−110  
GAIN  
Gain Range  
Gain Error  
G = 1, 2, 5, 10  
OUT = 10 V  
1
10  
V/V  
G = 1  
G = 2, 5, 10  
0.03  
0.04  
%
%
Gain Nonlinearity  
G = 1  
G = 2  
G = 5  
G = 10  
OUT = −10 V to +10 V  
RL = 10 kΩ, 2 kΩ, 600 Ω  
RL = 10 kΩ, 2 kΩ, 600 Ω  
RL = 10 kΩ, 2 kΩ, 600 Ω  
RL = 10 kΩ, 2 kΩ, 600 Ω  
All gains  
6
8
8
10  
10  
ppm  
ppm  
ppm  
ppm  
Gain vs. Temperature  
INPUT  
ppm/°C  
Input Impedance  
Differential  
5.3||0.5  
1.25||2  
GΩ||pF  
GΩ||pF  
V
V
Common Mode  
Input Operating Voltage Range  
Over Temperature  
OUTPUT  
VS = 5 V to 15 V  
T = −40°C to +85°C  
−VS + 1.5  
−VS + 1.6  
+VS − 1.5  
+VS − 1.7  
Output Swing  
Over Temperature  
Short-Circuit Current  
REFERENCE INPUT  
RIN  
−13.5  
−13.5  
+13.5  
+13.5  
V
V
mA  
T = −40°C to +85°C  
+IN, −IN, REF = 0  
37  
20  
kΩ  
μA  
V
IIN  
1
+VS  
Voltage Range  
Gain to Output  
DIGITAL LOGIC  
Digital Ground Voltage, DGND  
Digital Input Voltage Low  
Digital Input Voltage High  
Digital Input Current  
Gain Switching Time1  
tSU  
−VS  
1
0
0.0001  
V/V  
Referred to GND  
Referred to GND  
Referred to GND  
−VS + 4.25  
DGND  
2.8  
+VS − 2.7  
2.1  
+VS  
V
V
V
μA  
ns  
ns  
ns  
ns  
ns  
1
325  
See Figure 3 timing diagram  
See Figure 3 timing diagram  
See Figure 3 timing diagram  
See Figure 3 timing diagram  
20  
10  
20  
40  
tHD  
t WR  
-LOW  
t WR  
-HIGH  
Rev. C | Page 4 of 24  
Data Sheet  
AD8250  
Parameter  
Conditions  
Min  
Typ  
Max  
Unit  
POWER SUPPLY  
Operating Range  
Quiescent Current, +IS  
Quiescent Current, −IS  
Over Temperature  
TEMPERATURE RANGE  
Specified Performance  
±5  
±±5  
4.5  
4.5  
4.5  
V
4.±  
3.7  
mA  
mA  
mA  
T = −40°C to +85°C  
−40  
+85  
°C  
± Add time for the output to slew and settle to calculate the total time for a gain change.  
TIMING DIAGRAM  
tWR-HIGH  
tWR-LOW  
WR  
tSU  
tHD  
A0, A1  
Figure 3. Timing Diagram for Latched Gain Mode (See the Timing for Latched Gain Mode Section)  
Rev. C | Page 5 of 24  
 
 
 
AD8250  
Data Sheet  
ABSOLUTE MAXIMUM RATINGS  
Table 3.  
The power dissipated in the package (PD) is the sum of the  
quiescent power dissipation and the power dissipated in the  
package due to the load drive for all outputs. The quiescent  
power is the voltage between the supply pins (VS) times the  
quiescent current (IS). Assuming that the load (RL) is referenced  
to midsupply, the total drive power is VS/2 × IOUT, some of which  
is dissipated in the package and some in the load (VOUT × IOUT).  
Parameter  
Rating  
Supply Voltage  
Power Dissipation  
17 V  
See Figure 4  
Indefinite1  
+VS + 13 V, −VS − 13 V  
+VS + 13 V, −VS − 13 V2  
VS  
−65°C to +125°C  
−40°C to +85°C  
Output Short-Circuit Current  
Common-Mode Input Voltage  
Differential Input Voltage  
Digital Logic Inputs  
Storage Temperature Range  
Operating Temperature Range3  
The difference between the total drive power and the load  
power is the drive power dissipated in the package.  
PD = Quiescent Power + (Total Drive Power Load Power)  
Lead Temperature (Soldering, 10 sec) 300°C  
2
Junction Temperature  
140°C  
VS VOUT  
VOUT  
RL  
PD =  
(
VS ×IS  
)
+
×
θJA (Four-Layer JEDEC Standard Board)  
Package Glass Transition Temperature  
112°C/W  
140°C  
2
RL  
In single-supply operation with RL referenced to −VS, the worst  
case is VOUT = VS/2.  
1 Assumes that the load is referenced to midsupply.  
2 Current must be kept to less than 6 mA.  
3 Temperature for specified performance is −40°C to +85°C. For performance  
to 125°C, see the Typical Performance Characteristics section.  
Airflow increases heat dissipation, effectively reducing θJA. In  
addition, more metal directly in contact with the package leads  
from metal traces, through holes, ground, and power planes  
reduces the θJA.  
Stresses above those listed under Absolute Maximum Ratings  
may cause permanent damage to the device. This is a stress  
rating only; functional operation of the device at these or any  
other conditions above those indicated in the operational section of  
this specification is not implied. Exposure to absolute maximum  
rating conditions for extended periods may affect device reliability.  
Figure 4 shows the maximum safe power dissipation in the  
package vs. the ambient temperature on a four-layer JEDEC  
standard board.  
2.00  
1.75  
1.50  
1.25  
1.00  
0.75  
0.50  
0.25  
0
MAXIMUM POWER DISSIPATION  
The maximum safe power dissipation in the AD8250 package is  
limited by the associated rise in junction temperature (TJ) on  
the die. The plastic encapsulating the die locally reaches the  
junction temperature. At approximately 140°C, which is the  
glass transition temperature, the plastic changes its properties.  
Even temporarily exceeding this temperature limit can change  
the stresses that the package exerts on the die, permanently  
shifting the parametric performance of the AD8250. Exceeding  
a junction temperature of 140°C for an extended period can  
result in changes in silicon devices, potentially causing failure.  
–40  
–20  
0
20  
40  
60  
80  
100  
120  
The still-air thermal properties of the package and PCB (θJA),  
the ambient temperature (TA), and the total power dissipated in  
the package (PD) determine the junction temperature of the die.  
The junction temperature is calculated as  
AMBIENT TEMPERATURE (°C)  
Figure 4. Maximum Power Dissipation vs. Ambient Temperature  
ESD CAUTION  
TJ = TA + (PD × θJA)  
Rev. C | Page 6 of 24  
 
 
 
 
 
Data Sheet  
AD8250  
PIN CONFIGURATION AND FUNCTION DESCRIPTIONS  
–IN  
1
2
3
4
5
10  
9
+IN  
DGND  
REF  
AD8250  
TOP VIEW  
(Not to Scale)  
–V  
8
+V  
S
S
A0  
A1  
7
OUT  
WR  
6
Figure 5. Pin Configuration  
Table 4. Pin Function Descriptions  
Pin No.  
Mnemonic  
Description  
1
2
3
4
5
6
7
8
9
10  
−IN  
DGND  
−VS  
A0  
A1  
Inverting Input Terminal. True differential input.  
Digital Ground.  
Negative Supply Terminal.  
Gain Setting Pin (LSB).  
Gain Setting Pin (MSB).  
Write Enable.  
WR  
OUT  
+VS  
REF  
Output Terminal.  
Positive Supply Terminal.  
Reference Voltage Terminal.  
Noninverting Input Terminal. True differential input.  
+IN  
Rev. C | Page 7 of 24  
 
AD8250  
Data Sheet  
TYPICAL PERFORMANCE CHARACTERISTICS  
TA = 25°C, +VS = +15 V, VS = −15 V, RL = 10 kΩ, unless otherwise noted.  
500  
400  
1400  
1200  
1000  
800  
600  
400  
200  
0
300  
200  
100  
0
–30  
–20  
–10  
0
10  
20  
30  
–120 –90  
–60  
–30  
0
30  
60  
90  
120  
INPUT OFFSET CURRENT (nA)  
CMRR (µV/V)  
Figure 9. Typical Distribution of Input Offset Current  
Figure 6. Typical Distribution of CMRR, G = 1  
90  
350  
300  
80  
70  
60  
50  
40  
30  
20  
10  
0
250  
200  
150  
G = 1  
G = 2  
G = 5  
100  
G = 10  
50  
0
1
10  
100  
1k  
10k  
100k  
–200 –150 –100  
–50  
0
50  
100  
150  
200  
FREQUENCY (Hz)  
OFFSET VOLTAGE RTI (µV)  
Figure 7. Typical Distribution of Offset Voltage, VOSI  
Figure 10. Voltage Spectral Density Noise vs. Frequency  
600  
500  
400  
300  
200  
100  
0
2µV/DIV  
1s/DIV  
–30  
–20  
–10  
0
10  
20  
30  
INPUT BIAS CURRENT (nA)  
Figure 8. Typical Distribution of Input Bias Current  
Figure 11. 0.1 Hz to 10 Hz RTI Voltage Noise, G = 1  
Rev. C | Page 8 of 24  
 
Data Sheet  
AD8250  
150  
130  
110  
90  
G = 10  
G = 2  
G = 5  
G = 1  
70  
50  
30  
1µV/DIV  
1s/DIV  
10  
1
10  
100  
1k  
10k  
100k  
1M  
FREQUENCY (Hz)  
Figure 12. 0.1 Hz to 10 Hz RTI Voltage Noise, G = 10  
Figure 15. Positive PSRR vs. Frequency, RTI  
150  
130  
110  
90  
18  
16  
14  
12  
10  
8
G = 10  
G = 5  
G = 2  
70  
G = 1  
6
50  
4
30  
2
10  
0
1
10  
100  
1k  
10k  
100k  
1
10  
100  
1k  
10k  
100k  
1M  
FREQUENCY (Hz)  
FREQUENCY (Hz)  
Figure 13. Current Noise Spectral Density vs. Frequency  
Figure 16. Negative PSRR vs. Frequency, RTI  
10  
9
8
7
6
5
4
3
2
1
0
140pA/DIV  
1s/DIV  
0.01  
0.1  
1
10  
WARMUP TIME (Minutes)  
Figure 14. 0.1 Hz to 10 Hz Current Noise  
Figure 17. Change in Offset Voltage, RTI vs. Warmup Time  
Rev. C | Page 9 of 24  
AD8250  
Data Sheet  
10  
8
15  
10  
5
6
4
I
I
+
B
2
0
0
–2  
–4  
–6  
–8  
–10  
B
–5  
–10  
–15  
I
OS  
–50  
–30  
–10  
10  
30  
50  
70  
90  
110  
130  
–40 –25 –10  
5
20  
35  
50  
65  
80  
95 110 125  
TEMPERATURE (°C)  
TEMPERATURE (°C)  
Figure 21. CMRR vs. Temperature, G = 1  
Figure 18. Input Bias Current and Offset Current vs. Temperature  
25  
140  
G = 10  
G = 5  
G = 10  
G = 5  
20  
15  
10  
5
120  
100  
G = 1  
G = 2  
G = 2  
G = 1  
80  
60  
40  
20  
0
–5  
–10  
1k  
10k  
100k  
1M  
10M  
100M  
1
10  
100  
1k  
10k  
100k  
1M  
FREQUENCY (Hz)  
FREQUENCY (Hz)  
Figure 22. Gain vs. Frequency  
Figure 19. CMRR vs. Frequency  
40  
30  
20  
140  
120  
100  
80  
f = 1kHz  
G = 10  
G = 5  
10  
0
G = 2  
G = 1  
–10  
–20  
60  
40  
–30  
–40  
20  
–10  
–8  
–6  
–4  
–2  
0
2
4
6
8
10  
1
10  
100  
1k  
10k  
100k  
1M  
OUTPUT VOLTAGE (V)  
FREQUENCY (Hz)  
Figure 23. Gain Nonlinearity vs. Output Voltage, G = 1, RL = 10 kΩ, 2 kΩ, 600 Ω  
Figure 20. CMRR vs. Frequency, 1 kΩ Source Imbalance  
Rev. C | Page 10 of 24  
Data Sheet  
AD8250  
16  
12  
8
40  
0V, +13.8V  
= ±15V  
f = 1kHz  
30  
20  
V
S
–13.8V, +6.9V  
+13.8V, +6.9V  
0V, +3.7V  
4
10  
0
–3.8V, +1.9V  
+3.9V, +1.9V  
V
= ±5V  
0
S
–3.8V, –1.9V  
+3.8V, –2.1V  
–4  
–8  
–12  
–16  
–10  
–20  
0V, –4.0V  
–13.8V, –6.9V  
+13.8V, –6.9V  
–30  
–40  
0V, –14V  
0
–10  
–8  
–6  
–4  
–2  
0
2
4
6
8
10  
–16  
–12  
–8  
–4  
4
8
12  
16  
OUTPUT VOLTAGE (V)  
OUTPUT VOLTAGE (V)  
Figure 24. Gain Nonlinearity vs. Output Voltage, G = 2, RL = 10 kΩ, 2 kΩ, 600 Ω  
Figure 27. Input Common-Mode Voltage Range vs. Output Voltage, G = 1  
16  
40  
0V, +13.8V  
= ±15V  
–14.1V, +13.6V  
+13.6V, +13.1V  
f = 1kHz  
V
12  
8
30  
20  
S
+0V, +3.5V  
4
10  
0
–4.2V, +2.2V  
+4.3V, +2.1V  
V
= ±5V  
0
S
–4.2V, –2.0V  
+4.3V, –2.1V  
–4  
–8  
–12  
–16  
–10  
–20  
0V, –4.1V  
–30  
–40  
–14.1V, –13.6V  
–16 –12 –8  
+13.6V, –13.1V  
8 12 16  
0V, –14V  
0
–10  
–8  
–6  
–4  
–2  
0
2
4
6
8
10  
–4  
4
OUTPUT VOLTAGE (V)  
OUTPUT VOLTAGE (V)  
Figure 25. Gain Nonlinearity vs. Output Voltage, G = 5, RL = 10 kΩ, 2 kΩ, 600 Ω  
Figure 28. Input Common-Mode Voltage Range vs. Output Voltage, G = 10  
40  
35  
f = 1kHz  
I
I
I
+
30  
25  
20  
15  
10  
5
B
B
30  
20  
OS  
10  
0
–10  
–20  
0
–5  
–10  
–15  
–30  
–40  
–10  
–8  
–6  
–4  
–2  
0
2
4
6
8
10  
–15  
–10  
–5  
0
5
10  
15  
OUTPUT VOLTAGE (V)  
COMMON-MODE VOLTAGE (V)  
Figure 26. Gain Nonlinearity vs. Output Voltage, G = 10, RL = 10 kΩ, 2 kΩ, 600 Ω  
Figure 29. Input Bias Current and Offset Current vs. Common-Mode Voltage  
Rev. C | Page 11 of 24  
 
 
AD8250  
Data Sheet  
+V  
+V  
S
S
–0.2  
–0.4  
–0.6  
–0.8  
–1.0  
+125°C  
–1  
–2  
+85°C  
+25°C  
+125°C  
–40°C  
+25°C  
+25°C  
+85°C  
–40°C  
–40°C  
+1.0  
+0.8  
+0.6  
+0.4  
+0.2  
+2  
+1  
+85°C  
–40°C  
+25°C  
+85°C  
+125°C  
+125°C  
10  
SUPPLY VOLTAGE (±V )  
–V  
–V  
S
S
4
6
8
12  
14  
16  
4
6
8
10  
12  
14  
16  
SUPPLY VOLTAGE (±V )  
S
S
Figure 30. Input Voltage Limit vs. Supply Voltage, G = 1, VREF = 0 V, RL = 10 kΩ  
Figure 33. Output Voltage Swing vs. Supply Voltage, G = 10, RL = 10 kΩ  
15  
15  
+25°C  
+V  
S
10  
5
10  
–40°C  
FAULT CONDITION  
(OVER DRIVEN INPUT)  
G = 10  
FAULT CONDITION  
(OVER DRIVEN INPUT)  
G = 10  
5
+IN  
+85°C  
+125°C  
0
0
–IN  
+85°C  
–5  
–10  
–15  
–5  
+125°C  
–10  
–40°C  
–V  
S
+25°C  
–15  
–16  
–12  
–8  
–4  
0
4
8
12  
16  
100  
1k  
10k  
DIFFERENTIAL INPUT VOLTAGE (V)  
LOAD RESISTANCE ()  
Figure 31. Fault Current Draw vs. Input Voltage, G = 10, RL = 10 kΩ  
Figure 34. Output Voltage Swing vs. Load Resistance  
+V  
S
+V  
S
–0.2  
+85°C  
+125°C  
–0.4  
–0.8  
–1.2  
–1.6  
–2.0  
+2.0  
+1.6  
+1.2  
+0.8  
+0.4  
–0.4  
+125°C  
–0.6  
–0.8  
–1.0  
+25°C  
–40°C  
+25°C  
+25°C  
+85°C  
+85°C  
–40°C  
–40°C  
+1.0  
+0.8  
+0.6  
+0.4  
+0.2  
+25°C  
–40°C  
+125°C  
+125°C  
8
+85°C  
4
–V  
S
–V  
S
0
2
6
10  
12  
14  
16  
4
6
8
10  
12  
14  
16  
OUTPUT CURRENT (mA)  
SUPPLY VOLTAGE (±V )  
S
Figure 32. Output Voltage Swing vs. Supply Voltage, G = 10, RL = 2 kΩ  
Figure 35. Output Voltage Swing vs. Output Current  
Rev. C | Page 12 of 24  
Data Sheet  
AD8250  
100pF  
NO  
LOAD  
47pF  
5V/DIV  
605ns TO 0.01%  
635ns TO 0.001%  
0.002%/DIV  
20mV/DIV  
2µs/DIV  
2µs/DIV  
TIME (µs)  
TIME (µs)  
Figure 36. Small Signal Pulse Response for Various Capacitive Loads  
Figure 39. Large Signal Pulse Response and Settling Time  
G = 5, RL = 10 kΩ  
5V/DIV  
5V/DIV  
585ns TO 0.01%  
615ns TO 0.001%  
648ns TO 0.01%  
685ns TO 0.001%  
0.002%/DIV  
0.002%/DIV  
2µs/DIV  
2µs/DIV  
TIME (µs)  
TIME (µs)  
Figure 37. Large Signal Pulse Response and Settling Time,  
G = 1, RL = 10 kΩ  
Figure 40. Large Signal Pulse Response and Settling Time  
G = 10, RL = 10 kΩ  
5V/DIV  
605ns TO 0.01%  
635ns TO 0.001%  
0.002%/DIV  
20mV/DIV  
2µs/DIV  
2µs/DIV  
TIME (µs)  
TIME (µs)  
Figure 38. Large Signal Pulse Response and Settling Time  
G = 2, RL = 10 kΩ  
Figure 41. Small Signal Response  
G = 1, RL = 2 kΩ, CL = 100 pF  
Rev. C | Page 13 of 24  
AD8250  
Data Sheet  
–50  
–55  
G = 1  
G = 2  
G = 5  
G = 10  
–60  
–65  
–70  
–75  
–80  
–85  
–90  
–95  
–100  
–105  
–110  
–115  
–120  
20mV/DIV  
2µs/DIV  
2µs/DIV  
2µs/DIV  
TIME (µs)  
10  
100  
1k  
10k  
100k  
1M  
FREQUENCY (Hz)  
Figure 42. Small Signal Response  
G = 2, RL = 2 kΩ, CL = 100 pF  
Figure 45. Total Harmonic Distortion + Noise vs. Frequency,  
10 Hz to 22 kHz Band-Pass Filter, RL = 2 kΩ  
–50  
G = 1  
G = 2  
G = 5  
G = 10  
–60  
–70  
–80  
–90  
–100  
20mV/DIV  
–110  
10  
TIME (µs)  
100  
1k  
10k  
100k  
1M  
FREQUENCY (Hz)  
Figure 43. Small Signal Response  
G = 5, RL = 2 kΩ, CL = 100 pF  
Figure 46. Total Harmonic Distortion + Noise vs. Frequency,  
10 Hz to 500 kHz Band-Pass Filter, RL = 2 kΩ  
20mV/DIV  
TIME (µs)  
Figure 44. Small Signal Response,  
G = 10, RL = 2 kΩ, CL = 100 pF  
Rev. C | Page 14 of 24  
Data Sheet  
AD8250  
THEORY OF OPERATION  
+V  
–V  
+V  
–V  
S
S
A0  
A1  
2.2k  
+V  
–V  
S
S
S
2.2kΩ  
–IN  
10kΩ  
10kΩ  
A1  
S
+V  
S
DIGITAL  
GAIN  
OUT  
REF  
A3  
CONTROL  
–V  
+V  
S
S
+V  
–V  
S
10kΩ  
10kΩ  
A2  
+IN  
2.2kΩ  
–V  
S
+V  
–V  
+V  
S
S
S
2.2kΩ  
DGND  
WR  
–V  
S
S
Figure 47. Simplified Schematic  
Transparent Gain Mode  
The AD8250 is a monolithic instrumentation amplifier based  
on the classic, 3-op-amp topology as shown in Figure 47. It is  
fabricated on the Analog Devices, Inc., proprietary iCMOS®  
process that provides precision, linear performance, and a  
robust digital interface. A parallel interface allows users to  
digitally program gains of 1, 2, 5, and 10. Gain control is achieved  
by switching resistors in an internal, precision resistor array (as  
shown in Figure 47). Although the AD8250 has a voltage feedback  
topology, the gain bandwidth product increases for gains of 1, 2,  
and 5 because each gain has its own frequency compensation.  
This results in maximum bandwidth at higher gains.  
The easiest way to set the gain is to program it directly via a  
logic high or logic low voltage applied to A0 and A1. Figure 48  
shows an example of this gain setting method, referred to through-  
WR  
out the data sheet as transparent gain mode. Tie  
to the negative  
supply to engage transparent gain mode. In this mode, any change  
in voltage applied to A0 and A1 from logic low to logic high, or  
vice versa, immediately results in a gain change. Table 5 is the  
truth table for transparent gain mode, and Figure 48 shows the  
AD8250 configured in transparent gain mode.  
+15V  
All internal amplifiers employ distortion cancellation circuitry  
and achieve high linearity and ultralow THD. Laser trimmed  
resistors allow for a maximum gain error of less than 0.03%  
for G = 1 and minimum CMRR of 98 dB for G = 10. A pinout  
optimized for high CMRR over frequency enables the AD8250  
to offer a guaranteed minimum CMRR over frequency of 80 dB  
at 50 kHz (G = 1). The balanced input reduces the parasitics  
that, in the past, adversely affected CMRR performance.  
10μF  
0.1µF  
WR  
–15V  
+5V  
A1  
A0  
+IN  
+5V  
G = 10  
AD8250  
REF  
–IN  
DGND  
DGND  
GAIN SELECTION  
10μF  
0.1µF  
Logic low and logic high voltage limits are listed in the  
Specifications section. Typically, logic low is 0 V and logic high  
is 5 V; both voltages are measured with respect to DGND. See  
Table 2 for the permissible voltage range of DGND. The gain of  
the AD8250 can be set using two methods.  
–15V  
NOTE:  
1. IN TRANSPARENT GAIN MODE, WR IS TIED TO V .  
S
THE VOLTAGE LEVELS ON A0 AND A1 DETERMINE  
THE GAIN. IN THIS EXAMPLE, BOTH A0 AND A1 ARE  
SET TO LOGIC HIGH, RESULTING IN A GAIN OF 10.  
Figure 48. Transparent Gain Mode, A0 and A1 = High, G = 10  
Rev. C | Page 15 of 24  
 
 
 
 
AD8250  
Data Sheet  
Table 5. Truth Table Logic Levels for Transparent Gain Mode  
Table 6. Truth Table Logic Levels for Latched Gain Mode  
WR  
A1  
A0  
Gain  
WR  
A1  
A0  
Gain  
−VS  
−VS  
−VS  
−VS  
Low  
Low  
High  
High  
Low  
High  
Low  
High  
1
2
5
10  
High to low  
High to low  
High to low  
High to low  
Low to low  
Low to high  
High to high  
Low  
Low  
High  
High  
X1  
Low  
High  
Low  
High  
X1  
Change to 1  
Change to 2  
Change to 5  
Change to 10  
No change  
No change  
No change  
Latched Gain Mode  
X1  
X1  
X1  
X1  
Some applications have multiple programmable devices such as  
multiplexers or other programmable gain instrumentation  
amplifiers on the same PCB. In such cases, devices can share a  
1 X = don’t care.  
On power-up, the AD8250 defaults to a gain of 1 when in latched  
gain mode. In contrast, if the AD8250 is configured in transparent  
gain mode, it starts at the gain indicated by the voltage levels on  
A0 and A1 at power-up.  
WR  
data bus. The gain of the AD8250 can be set using  
as a latch,  
allowing other devices to share A0 and A1. Figure 49 shows a  
schematic using this method, known as latched gain mode. The  
WR  
AD8250 is in this mode when  
low, typically 5 V and 0 V, respectively. The voltages on A0  
WR  
is held at logic high or logic  
Timing for Latched Gain Mode  
and A1 are read on the downward edge of the  
signal as it  
In latched gain mode, logic levels at A0 and A1 have to be held  
for a minimum setup time, tSU, before the downward edge of  
transitions from logic high to logic low. This latches in the logic  
levels on A0 and A1, resulting in a gain change. See the truth  
table in Table 6 for more information on these gain changes.  
WR  
latches in the gain. Similarly, they must be held for a  
WR  
minimum hold time of tHD after the downward edge of  
to  
+15V  
ensure that the gain is latched in correctly. After tHD, A0 and A1  
can change logic levels, but the gain does not change (until the  
WR  
+5V  
0V  
+5V  
0V  
WR  
A1  
10μF  
0.1µF  
A1  
WR  
WR  
next downward edge of  
can be held high is t WR-HIGH, and the minimum duration that  
WR  
). The minimum duration that  
+5V  
0V  
A0  
A0  
+IN  
can be held low is t WR-LOW. Digital timing specifications are  
+
G = PREVIOUS G = 10  
STATE  
listed in Table 2. The time required for a gain change is dominated  
by the settling time of the amplifier. A timing diagram is shown  
in Figure 50.  
AD8250  
REF  
–IN  
When sharing a data bus with other devices, logic levels applied  
to those devices can potentially feed through to the output of  
the AD8250. Feedthrough can be minimized by decreasing the  
edge rate of the logic signals. Furthermore, careful layout of the  
PCB also reduces coupling between the digital and analog portions  
of the board. Pull-up or pull-down resistors should be used to  
provide a well-defined voltage at the A0 and A1 pins.  
DGND  
DGND  
10μF  
0.1µF  
–15V  
NOTE:  
1. ON THE DOWNWARD EDGE OF WR, AS IT TRANSITIONS  
FROM LOGIC HIGH TO LOGIC LOW, THE VOLTAGES ON A0  
AND A1 ARE READ AND LATCHED IN, RESULTING IN A  
GAIN CHANGE. IN THIS EXAMPLE, THE GAIN SWITCHES TO G = 10.  
Figure 49. Latched Gain Mode, G = 10  
tWR-HIGH  
tWR-LOW  
WR  
tSU  
tHD  
A0, A1  
Figure 50. Timing Diagram for Latched Gain Mode  
Rev. C | Page 16 of 24  
 
 
 
 
 
Data Sheet  
AD8250  
INCORRECT  
+V  
CORRECT  
+V  
POWER SUPPLY REGULATION AND BYPASSING  
S
S
The AD8250 has high PSRR. However, for optimal performance,  
a stable dc voltage should be used to power the instrumentation  
amplifier. Noise on the supply pins can adversely affect per-  
formance. As in all linear circuits, bypass capacitors must be  
used to decouple the amplifier.  
AD8250  
AD8250  
REF  
REF  
REF  
REF  
Place a 0.1 μF capacitor close to each supply pin. A 10 μF tantalum  
capacitor can be used farther away from the part (see Figure 51)  
and, in most cases, it can be shared by other precision integrated  
circuits.  
–V  
–V  
S
S
TRANSFORMER  
TRANSFORMER  
+V  
S
+V  
S
+V  
S
0.1µF  
WR  
A1  
10µF  
AD8250  
AD8250  
REF  
A0  
+IN  
–IN  
10M  
OUT  
LOAD  
AD8250  
–V  
–V  
S
S
THERMOCOUPLE  
THERMOCOUPLE  
REF  
+V  
+V  
S
S
DGND  
C
C
C
0.1µF  
10µF  
R
1
–V  
DGND  
S
fHIGH-PASS =  
AD8250  
2πRC  
AD8250  
C
Figure 51. Supply Decoupling, REF, and Output Referred to Ground  
REF  
R
INPUT BIAS CURRENT RETURN PATH  
–V  
–V  
S
S
The AD8250 input bias current must have a return path to its  
local analog ground. When the source, such as a thermocouple,  
cannot provide a return current path, one should be created  
(see Figure 52).  
CAPACITIVELY COUPLED  
CAPACITIVELY COUPLED  
Figure 52. Creating an IBIAS Return Path  
INPUT PROTECTION  
All terminals of the AD8250 are protected against ESD. Note  
that 2.2 kΩ series resistors precede the ESD diodes as shown in  
Figure 47. The resistors limit current into the diodes and allow  
for dc overload conditions 13 V above the positive supply and  
13 V below the negative supply. An external resistor should be  
used in series with each input to limit current for voltages greater  
than 13 V beyond either supply rail. In either scenario, the  
AD8250 safely handles a continuous 6 mA current at room  
temperature. For applications where the AD8250 encounters  
extreme overload voltages, external series resistors and low  
leakage diode clamps, such as BAV199Ls, FJH1100s, or SP720s,  
should be used.  
Rev. C | Page 17 of 24  
 
 
 
 
 
AD8250  
Data Sheet  
REFERENCE TERMINAL  
The output voltage of the AD8250 develops with respect to the  
potential on the reference terminal. Take care to tie REF to the  
appropriate local analog ground or to connect it to a voltage that  
is referenced to the local analog ground.  
The reference terminal, REF, is at one end of a 10 kΩ resistor  
(see Figure 47). The instrumentation amplifier output is referenced  
to the voltage on the REF terminal; this is useful when the output  
signal needs to be offset to voltages other than its local analog  
ground. For example, a voltage source can be tied to the REF  
pin to level shift the output so that the AD8250 can interface  
with a single-supply ADC. The allowable reference voltage  
range is a function of the gain, common-mode input, and  
supply voltages. The REF pin should not exceed either +VS  
or −VS by more than 0.5 V.  
Coupling Noise  
To prevent coupling noise onto the AD8250, do the following  
guidelines:  
Do not run digital lines under the device.  
Run the analog ground plane under the AD8250.  
For best performance, especially in cases where the output is  
not measured with respect to the REF terminal, source imped-  
ance to the REF terminal should be kept low because parasitic  
resistance can adversely affect CMRR and gain accuracy.  
Shield fast switching signals with digital ground to avoid  
radiating noise to other sections of the board, and never  
run them near analog signal paths.  
Avoid crossover of digital and analog signals.  
INCORRECT  
CORRECT  
Connect digital and analog ground at one point only  
(typically under the ADC).  
AD8250  
AD8250  
Use the large traces on power supply lines to ensure a low  
impedance path. Decoupling is necessary; follow the  
guidelines listed in the Power Supply Regulation and  
Bypassing section.  
V
REF  
V
REF  
+
OP1177  
Common-Mode Rejection  
The AD8250 has high CMRR over frequency, giving it greater  
immunity to disturbances, such as line noise and its associated  
harmonics, in contrast to typical instrumentation amplifiers  
whose CMRR falls off around 200 Hz. Typical instrumentation  
amplifiers often need common-mode filters at their inputs to  
compensate for this shortcoming. The AD8250 is able to reject  
CMRR over a greater frequency range, reducing the need for  
input common-mode filtering.  
Figure 53. Driving the Reference Pin  
COMMON-MODE INPUT VOLTAGE RANGE  
The 3-op-amp architecture of the AD8250 applies gain and then  
removes the common-mode voltage. Therefore, internal nodes  
in the AD8250 experience a combination of both the gained  
signal and the common-mode signal. This combined signal can be  
limited by the voltage supplies even when the individual input and  
output signals are not. Figure 27 and Figure 28 show the allowable  
common-mode input voltage ranges for various output voltages,  
supply voltages, and gains.  
Careful board layout maximizes system performance. To  
maintain high CMRR over frequency, lay out the input traces  
symmetrically. Ensure that the traces maintain resistive and  
capacitive balance; this holds for additional PCB metal layers  
under the input pins and traces. Source resistance and capaci-  
tance should be placed as close to the inputs as possible. Should a  
trace cross the inputs (from another layer), route it perpendicular  
to the input traces.  
LAYOUT  
Grounding  
In mixed-signal circuits, low level analog signals need to be  
isolated from the noisy digital environment. Designing with the  
AD8250 is no exception. Its supply voltages are referenced to an  
analog ground. Its digital circuit is referenced to a digital ground.  
Although it is convenient to tie both grounds to a single ground  
plane, the current traveling through the ground wires and PCB  
can cause errors. Therefore, use separate analog and digital ground  
planes. Analog and digital ground should meet at only one point:  
star ground.  
Rev. C | Page 18 of 24  
 
 
 
Data Sheet  
AD8250  
DRIVING AN ADC  
RF INTERFERENCE  
An instrumentation amplifier is often used in front of an ADC  
to provide CMRR. Usually, instrumentation amplifiers require a  
buffer to drive an ADC. However, the low output noise, low  
distortion, and low settle time of the AD8250 make it an excellent  
ADC driver.  
RF rectification is often a problem when amplifiers are used in  
applications where there are strong RF signals. The disturbance  
can appear as a small dc offset voltage. High frequency signals  
can be filtered with a low-pass RC network placed at the input  
of the instrumentation amplifier, as shown in Figure 54. The filter  
limits the input signal bandwidth according to the following  
relationship:  
In this example, a 1 nF capacitor and a 100 Ω resistor create an  
antialiasing filter for the AD7612. The 1 nF capacitor stores and  
delivers the necessary charge to the switched capacitor input of  
the ADC. The 100 ꢀ series resistor reduces the burden of the  
1 nF load from the amplifier and isolates it from the kickback  
current injected from the switched capacitor input of the AD7612.  
Selecting too small a resistor improves the correlation between  
the voltage at the output of the AD8250 and the voltage at the  
input of the AD7612 but may destabilize the AD8250. A trade-  
off must be made between selecting a resistor small enough to  
maintain accuracy and large enough to maintain stability.  
1
FilterFreq  
DIFF  
2R(2C C )  
D
C
1
FilterFreq  
CM  
2RC  
C
where CD ≥ 10 CC.  
+15V  
0.1µF  
+IN  
10µF  
+15V  
C
C
C
C
D
C
R
R
10μF  
0.1µF  
WR  
+12V  
0.1μF  
–12V  
0.1μF  
OUT  
A1  
AD8250  
A0  
+IN  
REF  
–IN  
100Ω  
1nF  
AD8250  
AD7612  
REF  
0.1µF  
10µF  
+5V  
ADR435  
–IN  
–15V  
DGND  
DGND  
10μF  
0.1µF  
Figure 54. RFI Suppression  
Values of R and CC should be chosen to minimize RFI. A  
mismatch between the R × CC at the positive input and the  
R × CC at the negative input degrades the CMRR of the AD8250.  
By using a value of CD that is 10 times larger than the value of  
CC, the effect of the mismatch is reduced and performance is  
improved.  
–15V  
Figure 55. Driving an ADC  
Rev. C | Page 19 of 24  
 
 
 
AD8250  
Data Sheet  
APPLICATIONS  
DIFFERENTIAL OUTPUT  
SETTING GAINS WITH A MICROCONTROLLER  
+15V  
In certain applications, it is necessary to create a differential  
signal. High resolution ADCs often require a differential input.  
In other cases, transmission over a long distance can require  
differential signals for better immunity to interference.  
10μF  
0.1µF  
WR  
A1  
MICRO-  
CONTROLLER  
A0  
+IN  
+
Figure 57 shows how to configure the AD8250 to output a  
differential signal. An op amp, the AD817, is used in an inverting  
topology to create a differential voltage. VREF sets the output  
midpoint according to the equation shown in the figure. Errors  
from the op amp are common to both outputs and are thus  
common mode. Likewise, errors from using mismatched resistors  
cause a common-mode dc offset error. Such errors are rejected  
in differential signal processing by differential input ADCs or  
instrumentation amplifiers.  
AD8250  
REF  
–IN  
DGND  
DGND  
10μF  
0.1µF  
–15V  
Figure 56. Programming Gain Using a Microcontroller  
When using this circuit to drive a differential ADC, VREF can be  
set using a resistor divider from the ADC reference to make the  
output ratiometric with the ADC.  
+12V  
0.1μF  
AMPLITUDE  
WR  
+5V  
A1  
A0  
+IN  
AMPLITUDE  
–5V  
+
V
A = V + V  
IN REF  
OUT  
2
+2.5V  
0V  
–2.5V  
AD8250  
V
G = 1  
IN  
TIME  
REF  
4.99kΩ  
0.1μF  
DGND  
–12V  
V
+
REF  
0V  
–12V  
10pF  
+12V  
AD817  
4.99kΩ  
AMPLITUDE  
0.1µF  
0.1µF  
–12V  
+12V  
10μF  
+2.5V  
0V  
10μF  
DGND  
–2.5V  
V
B = –V + V  
IN  
OUT  
REF  
TIME  
2
Figure 57. Differential Output with Level Shift  
Rev. C | Page 20 of 24  
 
 
 
 
Data Sheet  
AD8250  
0
–10  
DATA ACQUISITION  
–20  
The AD8250 makes an excellent instrumentation amplifier for  
use in data acquisition systems. Its wide bandwidth, low distortion,  
low settling time, and low noise enable it to condition signals in  
front of a variety of 16-bit ADCs.  
–30  
–40  
–50  
–60  
–70  
Figure 59 shows a schematic of the AD825x data acquisition  
demonstration board. The quick slew rate of the AD8250 allows  
it to condition rapidly changing signals from the multiplexed  
inputs. An FPGA controls the AD7612, AD8250, and ADG1209.  
In addition, mechanical switches and jumpers allow users to pin  
strap the gains when in transparent gain mode.  
–80  
–90  
–100  
–110  
–120  
–130  
–140  
0
5
10  
15  
20  
25  
30  
35  
40  
45  
50  
FREQUENCY (kHz)  
This system achieved −111 dB of THD at 1 kHz and a signal-to-  
noise ratio of 91 dB during testing, as shown in Figure 58.  
Figure 58. FFT of the AD825x DAQ Demo Board Using the AD8250,  
1 kHz Signal  
JMP  
JMP  
–V  
S
+12V  
–12V  
+12V  
14  
+
+
+5V  
2kΩ  
0.1µF  
10µF  
10µF  
GND  
2
V
DD  
DGND  
806Ω  
806Ω  
EN  
DGND  
2
JMP  
4
S1A  
S2A  
+CH1  
+CH2  
+5V  
2kΩ  
DGND  
5
806Ω  
806Ω  
ALTERA  
EPF6010ATC144-3  
+CH3  
+CH4  
6
7
S3A  
S4A  
6
DGND  
0Ω  
0Ω  
C
C
5
WR  
DGND  
OUT  
+IN  
8
9
10  
1
DA  
+
4
A1  
ADG1209  
S4B  
+IN  
A0  
REF  
9
806Ω  
7
AD7612  
ADR435  
AD8250  
C
–CH4  
10  
11  
12  
D
0Ω 49.9Ω  
–IN  
1nF  
806Ω  
806Ω  
–V  
3
DB  
S
S3B  
–CH3  
–CH2  
–CH1  
C
+V  
8
C
S
GND 15  
S2B  
S1B  
A0  
1
806Ω  
A1  
16  
C4  
0.1µF  
C3  
0.1µF  
V
SS  
3
+12V –12V  
JMP  
0.1µF  
+5V  
–12V  
2kΩ  
DGND  
JMP  
+5V  
R8  
2kΩ  
DGND  
Figure 59. Schematic of ADG1209, AD8250, and AD7612 in the AD825x DAQ Demo Board  
Rev. C | Page 21 of 24  
 
 
 
AD8250  
Data Sheet  
OUTLINE DIMENSIONS  
3.10  
3.00  
2.90  
10  
1
6
5
5.15  
4.90  
4.65  
3.10  
3.00  
2.90  
PIN 1  
IDENTIFIER  
0.50 BSC  
0.95  
0.85  
0.75  
15° MAX  
1.10 MAX  
0.70  
0.55  
0.40  
0.15  
0.05  
0.23  
0.13  
6°  
0°  
0.30  
0.15  
COPLANARITY  
0.10  
COMPLIANT TO JEDEC STANDARDS MO-187-BA  
Figure 60. 10-Lead Mini Small Outline Package [MSOP]  
(RM-10)  
Dimensions shown in millimeters  
ORDERING GUIDE  
Model1  
AD8250ARMZ  
AD8250ARMZ-RL  
AD8250ARMZ-R7  
AD8250-EVALZ  
Temperature Range  
–40°C to +85°C  
–40°C to +85°C  
Package Description  
Package Option  
RM-10  
RM-10  
Branding  
H00  
H00  
10-Lead Mini Small Outline Package [MSOP]  
10-Lead Mini Small Outline Package [MSOP]  
10-Lead Mini Small Outline Package [MSOP]  
Evaluation Board  
–40°C to +85°C  
RM-10  
H00  
1 Z = RoHS Compliant Part.  
Rev. C | Page 22 of 24  
 
 
 
Data Sheet  
NOTES  
AD8250  
Rev. C | Page 23 of 24  
AD8250  
NOTES  
Data Sheet  
©2007–2013 Analog Devices, Inc. All rights reserved. Trademarks and  
registered trademarks are the property of their respective owners.  
D06288-0-5/13(C)  
Rev. C | Page 24 of 24  

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