AD8276BRMZ-R7 Analog Devices Inc, AD8276BRMZ-R7 Datasheet - Page 12

• Manufacturer Part Number: AD8276BRMZ-R7
• Description: Single G=1 LowPower,WideInputRange
• Manufacturer: Analog Devices Inc
• Type: Instrumentation Amplifierr

Specifications of AD8276BRMZ-R7

• Design Resources: High Precision, Low Cost Current Sources Using AD8276 and AD8603 (CN0099)
• Amplifier Type: Differential
• Number Of Circuits: 1
• Output Type: Rail-to-Rail
• Slew Rate: 1.1 V/µs
• Gain Bandwidth Product: 550kHz
• Voltage - Input Offset: 100µV
• Current - Supply: 200µA
• Current - Output / Channel: 15mA
• Voltage - Supply, Single/dual (±): 2 V ~ 36 V, ±2 V ~ 18 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-MSOP, Micro8™, 8-uMAX, 8-uSOP,
• Number Of Channels: 1
• Number Of Elements: 1
• Power Supply Requirement: Single/Dual
• Common Mode Rejection Ratio: 86dB
• Input Resistance: 0.08@±5VMohm
• Input Offset Voltage: 0.2@±5VmV
• Single Supply Voltage (typ): 3/5/9/12/15/18/24/28V
• Dual Supply Voltage (typ): ±3/±5/±9/±12/±15V
• Rail/rail I/o Type: Rail to Rail Output
• Single Supply Voltage (min): 2V
• Single Supply Voltage (max): 36V
• Dual Supply Voltage (min): ±2V
• Dual Supply Voltage (max): ±18V
• Operating Temp Range: -40C to 85C
• Operating Temperature Classification: Industrial
• Mounting: Surface Mount
• Pin Count: 8
• Package Type: MSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• -3db Bandwidth: -
• Current - Input Bias: -
• Lead Free Status / Rohs Status: Compliant
• Other names: AD8276BRMZ-R7TR

AD8276
THEORY OF OPERATION
CIRCUIT INFORMATION
The AD8276 consists of a low power, low noise op amp and
four laser-trimmed on-chip resistors. These resistors can
be externally connected to make a variety of amplifier confi-
gurations, including difference, noninverting, and inverting
configurations. Taking advantage of the integrated resistors
of the AD8276 provides the designer with several benefits
over a discrete design.
DC Performance
Much of the dc performance of op amp circuits depends on the
accuracy of the surrounding resistors. This can be verified by a
simple examination of the typical difference amplifier confi-
guration, as shown in Figure 36. The output voltage is
as long as the following ratio of the resistors is tightly matched:
The resistors on the AD8276 are laid out to optimize their
matching, and they are laser trimmed and tested for their
matching accuracy. Because of this trimming and testing, the
AD8276 can guarantee high accuracy and consistency for
specifications such as gain drift, common-mode rejection,
and gain error, even over a wide temperature range.
AC Performance
The feature size is much smaller in an IC than on a PCB, so
the corresponding parasitics are also smaller, which helps the
ac performance of the AD8276. For example, the positive and
negative input terminals of the AD8276 op amp are not pinned
out intentionally. By not connecting these nodes to the traces
on the PCB, the capacitance remains low, resulting in both
improved loop stability and common-mode rejection over
frequency.
V
R2
R1
OUT
=
=
R4
R3
R4
R3
IN–
IN+
(
Figure 35. Functional Block Diagram
V
2
3
IN
+
40kΩ
40kΩ
−
V
IN
+VS
–VS
−
7
4
)
AD8276
40kΩ
40kΩ
5
6
1
SENSE
OUT
REF
Rev. 0 | Page 12 of 16
DRIVING THE AD8276
With all configurations presenting at least several kilohms
(kΩ) of input resistance, the AD8276 is easy to drive. Drive
the AD8276 with a low impedance source: for example, another
amplifier. The gain accuracy and common-mode rejection of the
AD8276 depend on the matching of its resistors. Even source
resistance of a few ohms can have a substantial effect on these
specifications.
POWER SUPPLIES
Use a stable dc voltage to power the AD8276. Noise on the
supply pins can adversely affect performance. Place a bypass
capacitor of 0.1 μF between each supply pin and ground, as
close as possible to each supply pin. Use a tantalum capacitor
of 10 μF between each supply and ground. It can be farther
away from the supply pins and, typically, it can be shared by
other precision integrated circuits.
The AD8276 is specified at ±15 V, but it can be used with unba-
lanced supplies, as well. For example, −V
difference between the two supplies must be kept below 36 V.
INPUT VOLTAGE RANGE
The AD8276 is able to measure input voltages beyond the rails
because the internal resistors divide down the voltage before
it reaches the internal op amp. Figure 36 shows an example
of how the voltage division works in a difference amplifier con-
figuration. In order for the AD8276 to measure correctly, the
input voltages at the input nodes of the internal op amp must
stay within 1.5 V of the positive supply rail and can exceed the
negative supply rail by 0.1 V.
For best long-term reliability of the part, voltages at any of the
part’s inputs (Pin 1, Pin 2, Pin 3, or Pin 5) should stay within
+V
input voltages should not exceed ±30 V.
S
Figure 36. Voltage Division in the Difference Amplifier Configuration
− 40 V to −V
S
+ 40 V. For example, on ±10 V supplies,
R1 + R2
R2
R3
R1
(V
R2
IN+
)
V
V
R1 + R2
IN–
IN+
R2
R4
(V
IN+
S
= 0 V, +V
)
S
= 20 V. The