AD623ARZ Analog Devices Inc, AD623ARZ Datasheet - Page 12

• Manufacturer Part Number: AD623ARZ
• Description: IC AMP INST R-R LP 8SOIC
• Manufacturer: Analog Devices Inc
• Type: Low Powerr

Specifications of AD623ARZ

• Slew Rate: 0.3 V/µs
• Amplifier Type: Instrumentation
• Number Of Circuits: 1
• Output Type: Rail-to-Rail
• -3db Bandwidth: 800kHz
• Current - Input Bias: 17nA
• Voltage - Input Offset: 25µV
• Current - Supply: 375µA
• Voltage - Supply, Single/dual (±): 2.7 V ~ 12 V, ± 2.5 V ~ 6 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• No. Of Amplifiers: 1
• Input Offset Voltage: 200µV
• Gain Db Min: 1dB
• Gain Db Max: 1000dB
• Bandwidth: 800kHz
• Amplifier Output: Single Ended
• Cmrr: 110dB
• Supply Voltage Range: 2.7V To
• Common Mode Rejection Ratio: 110
• Current, Input Bias: 17 nA
• Current, Input Offset: 0.25 nA
• Current, Supply: 550 μA
• Impedance, Thermal: 155 °C/W
• Package Type: SOIC-N
• Power Dissipation: 650 mW
• Temperature, Operating, Range: -40 to +85 °C
• Voltage, Gain: 1-1000 V/V
• Voltage, Input: -4.85 to +3.5 V
• Voltage, Input Offset: 25 μV
• Voltage, Noise: 35 nV/sqrt Hz (Input), 50 nV/sqrt Hz (Output)
• Voltage, Output Swing: 0.01 to 4.5 V
• Voltage, Supply: 2.7 to 12 V
• Rohs Compliant: Yes
• Number Of Channels: 1
• Number Of Elements: 1
• Power Supply Requirement: Single/Dual
• Input Resistance: 2000@5VMohm
• Input Bias Current: 0.025@5VnA
• Single Supply Voltage (typ): 3/5/9V
• Dual Supply Voltage (typ): ±3/±5V
• Power Supply Rejection Ratio: 80dB
• Rail/rail I/o Type: Rail to Rail Output
• Single Supply Voltage (min): 2.7V
• Single Supply Voltage (max): 12V
• Dual Supply Voltage (min): ±2.5V
• Dual Supply Voltage (max): ±6V
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 8
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Output / Channel: -
• Gain Bandwidth Product: -
• Lead Free Status / Rohs Status: RoHS Compliant part Electrostatic Device

AD623
Desired
Gain
2
5
10
20
33
40
50
65
100
200
500
1000
INPUT AND OUTPUT OFFSET VOLTAGE
The low errors of the AD623 are attributed to two sources,
input and output errors. The output error is divided by the
programmed gain when referred to the input. In practice, the
input errors dominate at high gains and the output errors domi-
nate at low gains. The total V
RTI offset errors and noise voltages for different gains are shown
below in Table II.
Gain
1
2
5
10
20
50
100
1000 200
Total Error RTI = Input Error + (Output Error/G)
Total Error RTO = (Input Error × G) + Output Error
Max
Total Input
Offset Error
AD623A AD623B AD623A AD623B AD623A & AD623B
1200
700
400
300
250
220
210
V
Table I. Required Values of Gain Resistors
600
350
200
150
125
110
105
100
V
Table II. RTI Error Sources
1% Std Table
Value of R
100 k
24.9 k
11 k
5.23 k
3.09 k
2.55 k
2.05 k
1.58 k
1.02 k
499
200
100
V
IN
Max
Total Input
Offset Drift
12
7
4
3
2.5
2.2
2.1
2
R
V/ C
G
a. Dual Supply
OS
G
,
R
R
for a given gain is calculated as:
G
+V
G
–V
S
S
11
6
3
2
1.5
1.2
1.1
1
REF
OUTPUT
V/ C
–2.5V TO –6V
+2.5V TO +6V
0.1 F
0.1 F
Calculated Gain
Using 1% Resistors
2
5.02
10.09
20.12
33.36
40.21
49.78
64.29
99.04
201.4
501
1001
Total Input
Referred Noise
(nV/ Hz)
62
45
38
35
35
35
35
35
10 F
10 F
Figure 41. Basic Connections
V
REF (INPUT)
OUT
–12–
INPUT PROTECTION
Internal supply referenced clamping diodes allow the input,
reference, output and gain terminals of the AD623 to safely
withstand overvoltages of 0.3 V above or below the supplies.
This is true for all gains, and for power on and off. This last
case is particularly important since the signal source and ampli-
fier may be powered separately.
If the overvoltage is expected to exceed this value, the current
through these diodes should be limited to about 10 mA using
external current limiting resistors. This is shown in Figure 42.
The size of this resistor is defined by the supply voltage and the
required overvoltage protection.
RF INTERFERENCE
All instrumentation amplifiers can rectify high frequency out-of-
band signals. Once rectified, these signals appear as dc offset
errors at the output. The circuit of Figure 43 provides good RFI
suppression without reducing performance within the in amps
pass band. Resistor R1 and capacitor C1 (and likewise, R2 and
C2) form a low-pass RC filter that has a –3 dB BW equal to:
F = 1/(2 π R1C1). Using the component values shown, this
filter has a –3 dB bandwidth of approximately 40 kHz. Resistors
R1 and R2 were selected to be large enough to isolate the
circuit’s input from the capacitors, but not large enough to
significantly increase the circuit’s noise. To preserve common-
mode rejection in the amplifier’s pass band, capacitors C1 and
C2 need to be 5% or better units, or low cost 20% units can be
tested and “binned” to provide closely matched devices.
Capacitor C3 is needed to maintain common-mode rejection at
the low frequencies. R1/R2 and C1/C2 form a bridge circuit
whose output appears across the in amp’s input pins. Any
mismatch between C1 and C2 will unbalance the bridge and
reduce common-mode rejection. C3 ensures that any RF signals
V
V
V
IN
OVER
OVER
R
G
b. Single Supply
R
R
R
R
+V
G
G
LIM
LIM
S
Figure 42. Input Protection
REF
OUTPUT
+3V TO +12V
1 = 10mA MAX
0.1 F
R
G
10 F
V
REF (INPUT)
OUT
+V
AD623
V
S
S
R
LIM
=
V
OVER
10mA
V
OUTPUT
S
+0.7V
REV. C