AD8202YRZ-RL Analog Devices Inc, AD8202YRZ-RL Datasheet - Page 14

• Manufacturer Part Number: AD8202YRZ-RL
• Description: IC,Differential Amplifier,SINGLE,SOP,8PIN,PLASTIC
• Manufacturer: Analog Devices Inc

Specifications of AD8202YRZ-RL

• Amplifier Type: Differential
• Number Of Circuits: 1
• Slew Rate: 0.28 V/µs
• Gain Bandwidth Product: 50kHz
• Current - Input Bias: 40nA
• Voltage - Input Offset: 1000µV
• Current - Supply: 250µA
• Voltage - Supply, Single/dual (±): 3.5 V ~ 12 V
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Output Type: -
• Current - Output / Channel: -
• -3db Bandwidth: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AD8202
APPLICATIONS
The AD8202 difference amplifier is intended for applications that
require extracting a small differential signal in the presence of
large common-mode voltages. The differential input resistance
is nominally 325 kΩ, and the device can tolerate common-mode
voltages higher than the supply voltage and lower than ground.
The open collector output stage sources current to within
20 mV of ground and to within 200 mV of V
CURRENT SENSING
High Line, High Current Sensing
Basic automotive applications using the large common-mode
range are shown in Figure 2 and Figure 3. The capability of the
device to operate as an amplifier in primary battery supply
circuits is shown in Figure 2; Figure 3 illustrates the ability
of the device to withstand voltages below system ground.
Low Current Sensing
The AD8202 is also used in low current sensing applications,
such as the 4 to 20 mA current loop shown in Figure 42. In such
applications, the relatively large shunt resistor can degrade the
common-mode rejection. Adding a resistor of equal value on the
low impedance side of the input corrects for this error.
GAIN ADJUSTMENT
The default gain of the preamplifier and buffer are ×10 and ×2,
respectively, resulting in a composite gain of ×20. With the
addition of external resistor(s) or trimmer(s), the gain can be
lowered, raised, or finely calibrated.
Gains Less than 20
Because the preamplifier has an output resistance of 100 kΩ,
an external resistor connected from Pin 3 and Pin 4 to GND
decreases the gain by a factor R
in Figure 43.
+
Figure 42. 4 to 20 mA Current Loop Receiver
10Ω
1%
10Ω
1%
EXT
+IN
–IN
/(100 kΩ + R
AD8202
GND
NC
+V
5V
A1
NC = NO CONNECT
S
S
OUT
.
A2
EXT
) as shown
OUTPUT
Rev. D | Page 14 of 20
The overall bandwidth is unaffected by changes in gain by using
this method, although there may be a small offset voltage due
to the imbalance in source resistances at the input to the buffer.
This can often be ignored, but if desired, it can be nulled by
inserting a resistor equal to 100 kΩ minus the parallel sum of R
and 100 kΩ, in series with Pin 4. For example, with R
(yielding a composite gain of ×10), the optional offset nulling
resistor is 50 kΩ.
Gains Greater Than 20
Connecting a resistor from the output of the buffer amplifier
to its noninverting input, as shown in Figure 44, increases the
gain. The gain is multiplied by the factor R
for example, the gain is doubled for R
gains as high as 50 are achievable in this way. The accuracy of
the gain becomes critically dependent on the resistor value at
high gains. Also, the effective input offset voltage at Pin 1 and
Pin 8 (about six times the actual offset of A1) limits the part’s
use in high gain, dc-coupled applications.
V
V
CM
CM
V
V
DIFF
DIFF
V
V
2
2
NC = NO CONNECT
DIFF
DIFF
2
2
NC = NO CONNECT
Figure 43. Adjusting for Gains Less than 20
Figure 44. Adjusting for Gains > 20
AD8202
+IN
–IN
100kΩ
10kΩ
AD8202
+IN
100kΩ
–IN
10kΩ
GND
NC
GND
NC
10kΩ
+V
+V
A1
S
S
10kΩ
+V
+V
A1
OUT
A2
S
S
EXT
OUT
A2
R
R
= 200 kΩ. Overall
EXT
EXT
EXT
GAIN =
R
EXT
/(R
GAIN =
R
OUT
EXT
= 100kΩ
OUT
EXT
R
= 100kΩ
EXT
EXT
R
− 100 kΩ);
20R
EXT
20R
+ 100kΩ
= 100 kΩ
20 – GAIN
EXT
– 100kΩ
GAIN – 20
EXT
GAIN
GAIN
EXT