AMP04FSZ-RL Analog Devices Inc, AMP04FSZ-RL Datasheet - Page 6

• Manufacturer Part Number: AMP04FSZ-RL
• Description: UNITY GAIN DIFF AM IC
• Manufacturer: Analog Devices Inc

Specifications of AMP04FSZ-RL

• Amplifier Type: Instrumentation
• Number Of Circuits: 1
• -3db Bandwidth: 700kHz
• Current - Input Bias: 22nA
• Voltage - Input Offset: 30µV
• Current - Supply: 750µA
• Current - Output / Channel: 30mA
• Voltage - Supply, Single/dual (±): 5 V ~ 30 V, ±2.5 V ~ 15 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Output Type: -
• Slew Rate: -
• Gain Bandwidth Product: -
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

AMP04
APPLICATIONS
Common-Mode Rejection
The purpose of the instrumentation amplifier is to amplify the
difference between the two input signals while ignoring offset
and noise voltages common to both inputs. One way of judging
the device’s ability to reject this offset is the common-mode
gain, which is the ratio between a change in the common-mode
voltage and the resulting output voltage change. Instrumenta-
tion amplifiers are often judged by the common-mode rejection
ratio, which is equal to 20 × log
differential signal gain to the common-mode gain, commonly
called the CMRR. The AMP04 offers excellent CMRR, guaran-
teed to be greater than 90 dB at gains of 100 or greater. Input
offsets attain very low temperature drift by proprietary laser-
trimmed thin-film resistors and high gain amplifiers.
Input Common-Mode Range Includes Ground
The AMP04 employs a patented topology (Figure 1) that uniquely
allows the common-mode input voltage to truly extend to zero
volts where other instrumentation amplifiers fail. To illustrate,
take for example the single supply, gain of 100 instrumentation
amplifier as in Figure 2. As the inputs approach zero volts, in
order for the output to go positive, amplifier A’s output (V
must be allowed to go below ground, to –0.094 volts. Clearly
this is not possible in a single supply environment. Consequently
this instrumentation amplifier configuration’s input common-mode
voltage cannot go below about 0.4 volts. In comparison, the
AMP04 has no such restriction. Its inputs will function with a
zero-volt common-mode voltage.
IN(–)
IN(+)
V
IN
0.01V
+
–
0V
100k
INPUT BUFFERS
0V
REF
4.7 A
4.7 A
A
20k
100k
11k
–0.094V
V
2127
R
OA
GAIN
10
20k
of the ratio of the user-selected
11k
5.2 A
0.01V
100k
B
100k
V
OB
V
OUT
V
OUT
OA
)
Input Common-Mode Voltage Below Ground
Although not tested and guaranteed, the AMP04 inputs are
biased in a way that they can amplify signals linearly with common-
mode voltage as low as –0.25 volts below ground. This holds
true over the industrial temperature range from –40°C to +85°C.
Extended Positive Common-Mode Range
On the high side, other instrumentation amplifier configurations,
such as the three op amp instrumentation amplifier, can have
severe positive common-mode range limitations. Figure 3 shows
an example of a gain of 1001 amplifier, with an input common-
mode voltage of 10 volts. For this circuit to function, V
swing to 15.01 volts in order for the output to go to 10.01 volts.
Clearly no op amp can handle this swing range (given a 15 V
supply) as the output will saturate long before it reaches the
supply rails. Again the AMP04’s topology does not have this
limitation. Figure 4 illustrates the AMP04 operating at the same
common-mode conditions as in Figure 3. None of the internal
nodes has a signal high enough to cause amplifier saturation. As
a result, the AMP04 can accommodate much wider common-
mode range than most instrumentation amplifiers.
10.00V
10.01V
10.00V
10.01V
200
100k
50 A
A
100k
B
100k
100
V
V
–15V
+15V
100 A
OB
OA
11k
5V
15.01V
10.01V
R
11k
R
R
11.111V
0.1 A
100.1 A
100k
+15V
–15V
R
V
10.01V
OUT
10V
OB
must