AD8227ARMZ Analog Devices Inc, AD8227ARMZ Datasheet - Page 22

• Manufacturer Part Number: AD8227ARMZ
• Description: IC AMP INSTR R-R 250KHZ 8MSOP
• Manufacturer: Analog Devices Inc

Specifications of AD8227ARMZ

• Slew Rate: 0.8 V/µs
• Amplifier Type: Instrumentation
• Number Of Circuits: 1
• Output Type: Rail-to-Rail
• -3db Bandwidth: 250kHz
• Current - Input Bias: 20nA
• Voltage - Input Offset: 200µV
• Current - Supply: 350µA
• Current - Output / Channel: 13mA
• Voltage - Supply, Single/dual (±): 2.2 V ~ 36 V, ±1.5 V ~ 18 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• No. Of Amplifiers: 1
• Input Offset Voltage: 200µV
• Bandwidth: 250kHz
• Amplifier Output: Rail To Rail
• Cmrr: 90dB
• Supply Voltage Range: ± 1.5V To ± 18V
• Supply Current: 350µA
• Amplifier: RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Gain Bandwidth Product: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AD8227
APPLICATIONS INFORMATION
DIFFERENTIAL DRIVE
Figure 64 shows how to configure the AD8227 for differential
output.
The differential output is set by the following equation:
The common-mode output is set by the following equation:
The advantage of this circuit is that the dc differential accuracy
depends on the AD8227 and not on the op amp or the resistors.
This circuit takes advantage of the AD8227’s precise control of
its output voltage relative to the reference voltage. Op amp dc
performance and resistor matching affect the dc common-mode
output accuracy. However, because common-mode errors are
likely to be rejected by the next device in the signal chain, these
errors typically have little effect on overall system accuracy.
V
V
DIFF_OUT
CM_OUT
+IN
–IN
RECOMMENDED OP AMPS: AD8515, AD8641, AD820.
RECOMMENDED R VALUES: 5kΩ to 20kΩ.
Figure 64. Differential Output Using an Op Amp
= (V
= V
AD8227
OUT+
OUT+
REF
− V
− V
OUT−
OUT−
R
R
)/2 = V
= Gain × (V
–
BIAS
OP AMP
V
IN+
BIAS
+
− V
+OUT
–OUT
IN−
)
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Tips for Best Differential Output Performance
For best ac performance, an op amp with at least 2 MHz gain
bandwidth and 1 V/μs slew rate is recommended. Good choices
for op amps are the AD8641, AD8515, or AD820.
Keep trace lengths from resistors to the inverting terminal of
the op amp as short as possible. Excessive capacitance at this
node can cause the circuit to be unstable. If capacitance cannot
be avoided, use lower value resistors.
PRECISION STRAIN GAGE
The low offset and high CMRR over frequency of the AD8227
make it an excellent choice for bridge measurements. The
bridge can be connected directly to the inputs of the amplifier
(see Figure 65).
350Ω
350Ω
350Ω
350Ω
Figure 65. Precision Strain Gage
10µF
0.1µF
R
G
+IN
–IN
5V
+
–
AD8227
2.5V