AD8205YRZ Analog Devices Inc, AD8205YRZ Datasheet - Page 8

• Manufacturer Part Number: AD8205YRZ
• Description: IC AMP DIFF 8SOIC
• Manufacturer: Analog Devices Inc
• Type: Differential Ampr

Specifications of AD8205YRZ

• Amplifier Type: Differential
• Number Of Circuits: 1
• Slew Rate: 0.5 V/µs
• -3db Bandwidth: 50kHz
• Voltage - Input Offset: 2000µV
• Current - Supply: 2mA
• Voltage - Supply, Single/dual (±): 4.5 V ~ 5.5 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Number Of Channels: 1
• Number Of Elements: 1
• Power Supply Requirement: Single
• Common Mode Rejection Ratio: 76dB
• Voltage Gain Db: 33.98dB
• Input Resistance: 0.4@5V@-40C TOMohm
• Input Offset Voltage: 2@5VmV
• Single Supply Voltage (typ): 5V
• Dual Supply Voltage (typ): Not RequiredV
• Power Supply Rejection Ratio: 70dB
• Rail/rail I/o Type: No
• Single Supply Voltage (min): 4.5V
• Single Supply Voltage (max): 5.5V
• Dual Supply Voltage (min): Not RequiredV
• Dual Supply Voltage (max): Not RequiredV
• Operating Temp Range: -40C to 125C
• Operating Temperature Classification: Automotive
• Mounting: Surface Mount
• Pin Count: 8
• Package Type: SOIC
• No. Of Amplifiers: 1
• Bandwidth: 50kHz
• Supply Voltage Range: 4.5V To 5.5V
• Supply Current: 2mA
• Amplifier Case Style: SOIC
• No. Of Pins: 8
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Output Type: -
• Current - Output / Channel: -
• Gain Bandwidth Product: -
• Current - Input Bias: -
• Lead Free Status / RoHS Status: Compliant, Lead free / RoHS Compliant

AD8205
THEORY OF OPERATION
The AD8205 is a single-supply difference amplifier that uses a
unique architecture to accurately amplify small differential
current shunt voltages in the presence of rapidly changing
common-mode voltages.
In typical applications, the AD8205 is used to measure current
by amplifying the voltage across a current shunt placed across
the inputs.
The gain of the AD8205 is 50 V/V, with an accuracy of 1.2%.
This accuracy is guaranteed over the operating temperature
range of −40°C to +125°C.
The input offset is less than 2 mV referred to the input at 25°C,
and 4.5 mV maximum referred to the input over the full
operating temperature range for the packaged part.
The AD8205 operates with a single supply from 4.5 V to
10 V (absolute maximum = 12.5 V). The supply current is
less than 2 mA.
High accuracy trimming of the internal resistors allows the
AD8205 to have a common-mode rejection ratio better than
78 dB from dc to 20 kHz.
The output offset can be adjusted from 0.05 V to 4.8 V (V+ = 5 V)
for unipolar and bipolar operation.
The AD8205 consists of two amplifiers (A1 and A2), a resistor
network, small voltage reference, and a bias circuit (not shown),
see Figure 13.
The set of input attenuators preceding A1 consist of R
R
voltage range of A1. The two attenuators form a balanced bridge
network. When the bridge is balanced, the differential voltage
created by a common-mode voltage is 0 V at the inputs of A1.
The input attenuation ratio is 1/16.7. The combined series
resistance of R
C
, which reduce the common-mode voltage to match the input
A
, R
B
, and R
C
is approximately 200 kΩ ± 20%.
A
, R
B
, and
Rev. B | Page 8 of 12
By attenuating the voltages at Pin 1 and Pin 8, the A1 amplifier
inputs are held within the power supply range, even if Pin 1 and
Pin 8 exceed the supply or fall below common (ground). A
reference voltage of 250 mV biases the attenuator above ground.
This allows the amplifier to operate in the presence of negative
common-mode voltages.
The input network also attenuates normal (differential) mode
voltages. A1 amplifies the attenuated signal by 26. The input
and output of this amplifier are differential to maximize the ac
common-mode rejection.
A2 converts the differential voltage from A1 into a single-ended
signal and provides further amplification. The gain of this
second stage is 32.15.
The reference inputs, V
to the positive input of A2, which allows the output offset to be
adjusted anywhere in the output operating range. The gain is
1 V/V from the reference pins to the output when the reference
pins are used in parallel. The gain is 0.5 V/V when they are used
to divide the supply.
The ratios of Resistors R
high level of precision to allow the common-mode rejection
ratio to exceed 80 dB. This is accomplished by laser trimming
the resistor ratio matching to better than 0.01%.
The total gain of 50 is made up of the input attenuation of
1/16.7 multiplied by the first stage gain of 26 and the second
stage gain of 32.15.
The output stage is Class A with a PNP pull-up transistor and a
300 μA current sink pull-down.
R
R
R
A
B
C
–IN
250mV
GND
R
R
R
A
B
C
+IN
A1
AD8205
R
F
Figure 13. Simplified Schematic
R
F
REF
A
, R
1 and V
R
R
D
E
B
, R
R
R
C
D
F
, R
REF
D
2, are tied through resistors
, and R
A2
F
are trimmed to a
R
R
REF
REF
V
V
V
OUT
REF
REF
1
2