AD8224ACPZ-RL Analog Devices Inc, AD8224ACPZ-RL Datasheet - Page 23

• Manufacturer Part Number: AD8224ACPZ-RL
• Description: IC,Instrumentation Amplifier,DUAL,LLCC,16PIN,PLASTIC
• Manufacturer: Analog Devices Inc

Specifications of AD8224ACPZ-RL

• Amplifier Type: Instrumentation
• Number Of Circuits: 2
• Output Type: Rail-to-Rail
• Slew Rate: 2 V/µs
• -3db Bandwidth: 1.5MHz
• Current - Input Bias: 25pA
• Voltage - Input Offset: 300µV
• Current - Supply: 750µA
• Current - Output / Channel: 15mA
• Voltage - Supply, Single/dual (±): 4.5 V ~ 36 V, ±2.25 V ~ 18 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 16-LFCSP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• For Use With: AD8224-EVALZ - BOARD EVALUATION AD8224
• Gain Bandwidth Product: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

For applications where the AD8224 encounters extreme
overload voltages, as in cardiac defibrillators, external series
resistors and low leakage diode clamps, such as BAV199Ls,
FJH1100s, or SP720s, should be used.
RF INTERFERENCE
RF rectification is often a problem in applications where there are
large RF signals. The problem appears as a small dc offset voltage.
The AD8224 by its nature has a 5 pF gate capacitance (C
inputs. Matched series resistors form a natural low-pass filter that
reduces rectification at high frequency (see Figure 60).
CAPACITIVELY COUPLED
C
C
TRANSFORMER
INCORRECT
AD8224
Figure 60. RFI Filtering Without External Capacitors
+V
AD8224
–V
+V
–V
S
S
S
S
R
R
REF
Figure 59. Creating an I
REF
0.1µF
0.1µF
+IN
–IN
f
HIGH-PASS
–V
+15V
–15V
S
C
–V
C
G
G
S
=
AD8224
CAPACITIVELY COUPLED
2πRC
1
10µF
10µF
BIAS
REF
C
C
Path
R
R
TRANSFORMER
+
+
CORRECT
AD8224
AD8224
V
+V
+V
–V
–V
OUT
S
S
S
S
G
) at its
REF
REF
Rev. B | Page 23 of 28
The relationship between external, matched series resistors and the
internal gate capacitance is expressed as
To eliminate high frequency common-mode signals while using
smaller source resistors, a low-pass RC network can be placed at
the input of the instrumentation amplifier (see Figure 61). The
filter limits the input signal bandwidth according to the
following relationship:
Mismatched C
The imbalance causes the AD8224 to treat what would have
been a common-mode signal as a differential signal. To reduce
the effect of mismatched external C
C
frequency lower than the common-mode frequency.
COMMON-MODE INPUT VOLTAGE RANGE
The 3-op amp architecture of the AD8224 applies gain and then
removes the common-mode voltage. Therefore, internal nodes
in the AD8224 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 24 through Figure 27 show the
allowable common-mode input voltage ranges for various
output voltages, supply voltages, and gains.
D
greater than 10 times C
FilterFreq
FilterFreq
FilterFreq
FilterFreq
4.02kΩ
4.02kΩ
R
R
C
DIFF
CM
DIFF
CM
capacitors result in mismatched low-pass filters.
C
C
C
=
=
C
D
C
=
=
2
2
Figure 61. RFI Suppression
2
2
π
π
π
π
RC
R
1nF
10nF
1nF
1
RC
R
1
(
C
2 (
G
1
C
C
G
. This sets the differential filter
C
0.1µF
0.1µF
+
D
C
+IN
–IN
1
+
G
)
C
AD8224
C
+15V
–15V
C
+
capacitors, select a value of
C
G
)
REF
10µF
10µF
V
OUT
+
+
AD8224