AD8624ACPZ-RL Analog Devices Inc, AD8624ACPZ-RL Datasheet - Page 15

• Manufacturer Part Number: AD8624ACPZ-RL
• Description: Quad Precision 36V,Low Power RRO
• Manufacturer: Analog Devices Inc

Specifications of AD8624ACPZ-RL

• Amplifier Type: Voltage Feedback
• Number Of Circuits: 4
• Output Type: Rail-to-Rail
• Slew Rate: 0.48 V/µs
• Gain Bandwidth Product: 560kHz
• Current - Input Bias: 45pA
• Voltage - Input Offset: 10µV
• Current - Supply: 215µA
• Current - Output / Channel: 40mA
• Voltage - Supply, Single/dual (±): ±2.5 V ~ 15 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 16-LFCSP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• -3db Bandwidth: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

APPLICATIONS INFORMATION
INPUT PROTECTION
The maximum differential input voltage that can be applied to
the AD8622/AD8624 is determined by the internal diodes
connected across its inputs and series resistors at each input. These
internal diodes and series resistors limit the maximum
differential input voltage to ±10 V and are needed to prevent base-
emitter junction breakdown from occurring in the input stage of
the AD8622/AD8624 when very large differential voltages are
applied. In addition, the internal resistors limit the currents that
flow through the diodes. However, in applications where large
differential voltages can be inadvertently applied to the device,
large currents may still flow through these diodes. In such a
case, external resistors must be placed at both inputs of the op
amp to limit the input currents to ±10 mA (see Figure 54).
PHASE REVERSAL
An undesired phenomenon, phase reversal (also known as
phase inversion) occurs in many op amps when one or both of
the inputs are driven beyond the specified input voltage range
(IVR), in effect reversing the polarity of the output. In some
cases, phase reversal can induce lockups and even cause
equipment damage as well as self destruction.
The AD8622/AD8624 amplifiers have been carefully designed to
prevent output phase reversal when both inputs are maintained
within the specified input voltage range. In addition, even if one
or both inputs exceed the input voltage range but remain within
the supply rails, the output still does not phase reverse. Figure 55
shows the input/output waveforms of the AD8622/AD8624
configured as a unity-gain buffer with a supply voltage of ±15 V.
R1
R2
Figure 54. Input Protection
2
3
500Ω
500Ω
AD862x
1
Rev. B | Page 15 of 20
MICROPOWER INSTRUMENTATION AMPLIFIER
The AD8622 is a dual, high precision, rail-to-rail output op amp
operating at just 215 μA quiescent current per amplifier. Its
ultralow offset, offset drift, and voltage noise, combined with its
very low bias current and high common-mode rejection ratio
(CMRR), are ideally suited for high accuracy and micropower
instrumentation amplifier.
Figure 56 shows the classic 2-op-amp instrumentation amplifier
with four resistors using the AD8622. The key to high CMRR
for this instrumentation amplifier are resistors that are well
matched from both the resistive ratio and the relative drift. For
true difference amplification, matching of the resistor ratio is
very important, where R3/R4 = R1/R2. Assuming perfectly
matched resistors, the gain of the circuit is 1 + R2/R1, which is
approximately 100. Tighter matching of two op amps in one
package, like the AD8622, offers a significant boost in
performance over the classical 3-op-amp configuration. Overall,
the circuit only requires about 430 μA of supply current.
NOTES
1. V
2. TYPICAL: 0.01mV < |V2 – V1| < 149.7mV
3. TYPICAL: –14.97V < V
4. USE MATCHED RESISTORS.
1MΩ
R4
O
V1
= 100(V2 – V1)
–
AD8622
+
10.1kΩ
+15V
–15V
Figure 56. Micropower Instrumentation Amplifier
1/2
V
R3
OUT
V
O
IN
Figure 55. No Phase Reversal
< +14.97V
10.1kΩ
R1
V2
TIME (200µs/DIV)
–
AD8622
+
+15V
–15V
1/2
1MΩ
R2
AD8622/AD8624
V
V
SY
O
= ±15V