OP184ES Analog Devices Inc, OP184ES Datasheet - Page 14

• Manufacturer Part Number: OP184ES
• Description: IC OPAMP GP R-R 4.25MHZ LN 8SOIC
• Manufacturer: Analog Devices Inc
• Type: General Purpose Amplifierr

Specifications of OP184ES

• Slew Rate: 4 V/µs
• Mounting Type: Surface Mount
• Rohs Status: RoHS non-compliant
• Design Resources: Variable Gain Noninverting Amplifier Using AD5292 and OP184 (CN0112) Variable Gain Inverting Amplifier Using AD5292 and OP184 (CN0113) Programmable High Voltage Source with Boosted Output Current Using AD5292, OP184, and MOSFETs (CN0115) Low-Noise Microwave fractional-N PLL using active loop filter and RF prescaler (CN0174)
• Amplifier Type: General Purpose
• Number Of Circuits: 1
• Output Type: Rail-to-Rail
• Gain Bandwidth Product: 4.25MHz
• Current - Input Bias: 80nA
• Voltage - Input Offset: 100µV
• Current - Supply: 2.25mA
• Current - Output / Channel: 10mA
• Voltage - Supply, Single/dual (±): 3 V ~ 36 V, ±1.5 V ~ 18 V
• Operating Temperature: -40°C ~ 125°C
• Package / Case: 8-SOIC (3.9mm Width)
• No. Of Amplifiers: 1
• Bandwidth: 3.25MHz
• No. Of Pins: 8
• Peak Reflow Compatible (260 C): No
• Input Bias Current: 60nA
• Input Offset Voltage Max: 65µV
• Leaded Process Compatible: No
• Rohs Compliant: No
• Rail/rail I/o Type: Rail to Rail Input/Output
• Number Of Elements: 1
• Unity Gain Bandwidth Product: 3.25MHz
• Common Mode Rejection Ratio: 60dB
• Input Offset Voltage: 65uV
• Single Supply Voltage (typ): 5/9/12/15/18/24/28V
• Voltage Gain In Db: 107.6dB
• Power Supply Rejection Ratio: 76dB
• Power Supply Requirement: Single/Dual
• Shut Down Feature: No
• Single Supply Voltage (min): 3V
• Single Supply Voltage (max): 36V
• Dual Supply Voltage (min): ±1.5V
• Dual Supply Voltage (max): ±18V
• Technology: Bipolar
• Operating Temp Range: -40C to 125C
• Operating Temperature Classification: Automotive
• Mounting: Surface Mount
• Pin Count: 8
• Package Type: SOIC N
• -3db Bandwidth: -
• Lead Free Status / Rohs Status: Not Compliant

OP184/OP284/OP484
APPLICATIONS INFORMATION
FUNCTIONAL DESCRIPTION
The OP184/OP284/OP484 are precision single-supply, rail-to-rail
operational amplifiers. Intended for the portable instrumentation
marketplace, the OPx84 family of devices combine the attributes
of precision, wide bandwidth, and low noise to make them a superb
choice in single-supply applications that require both ac and
precision dc performance. Other low supply voltage appli-
cations for which the OP284 is well suited are active filters,
audio microphone preamplifiers, power supply control, and
telecommunications. To combine all of these attributes with
rail-to-rail input/output operation, novel circuit design techniques
are used.
For example, Figure 44 illustrates a simplified equivalent circuit
for the input stage of the OP184/OP284/OP484. It comprises
an NPN differential pair, Q1→Q2, and a PNP differential pair,
Q3→Q4, operating concurrently. Diode Network D1→Diode
Network D2 serves to clamp the applied differential input
voltage to the OP284, thereby protecting the input transistors
against avalanche damage. Input stage voltage gains are kept low
for input rail-to-rail operation. The two pairs of differential
output voltages are connected to the second stage of the OP284,
which is a compound folded cascade gain stage. It is also in the
second gain stage, where the two pairs of differential output
voltages are combined into a single-ended, output signal voltage
used to drive the output stage. A key issue in the input stage is
the behavior of the input bias currents over the input common-
mode voltage range. Input bias currents in the OP284 are the
arithmetic sum of the base currents in Q1→Q3 and in Q2→Q4.
As a result of this design approach, the input bias currents in
the OP284 not only exhibit different amplitudes; they also
exhibit different polarities. This effect is best illustrated by
Figure 10. It is, therefore, of paramount importance that the
effective source impedances connected to the OP284 inputs
be balanced for optimum dc and ac performance.
+IN x
4kΩ
Q
R1
1
Figure 44. OP284 Equivalent Input Circuit
3kΩ
R3
Q3
V+
D2
V–
D1
I2
I1
Q4
R4
3kΩ
Q
R2
4kΩ
2
–I N x
–
–
V
V
01
02
Rev. I | Page 14 of 24
To achieve rail-to-rail output, the OP284 output stage design
employs a unique topology for both sourcing and sinking current.
This circuit topology is illustrated in Figure 45. The output stage
is voltage-driven from the second gain stage. The signal path
through the output stage is inverting; that is, for positive input
signals, Q1 provides the base current drive to Q6 so that it conducts
(sinks) current. For negative input signals, the signal path via
Q1→Q2→D1→Q4→Q3 provides the base current drive for Q5 to
conduct (source) current. Both amplifiers provide output current
until they are forced into saturation, which occurs at approxi-
mately 20 mV from the negative supply rail and 100 mV from
the positive supply rail.
Thus, the saturation voltage of the output transistors sets the
limit on the OP284 maximum output voltage swing. Output
short-circuit current limiting is determined by the maximum
signal current into the base of Q1 from the second gain stage.
Under output short-circuit conditions, this input current level
is approximately 100 μA. With transistor current gains around 200,
the short-circuit current limits are typically 20 mA. The output
stage also exhibits voltage gain. This is accomplished by the use
of common-emitter amplifiers, and, as a result, the voltage gain
of the output stage (thus, the open-loop gain of the device)
exhibits a dependence to the total load resistance at the output
of the OP284.
INPUT OVERVOLTAGE PROTECTION
As with any semiconductor device, if conditions exist where the
applied input voltages to the device exceed either supply voltage,
the input overvoltage I-V characteristic of the device must be
considered. When an overvoltage occurs, the amplifier could be
damaged, depending on the magnitude of the applied voltage
and the magnitude of the fault current. Figure 46 illustrates the
overvoltage I-V characteristic of the OP284. This graph was
generated with the supply pins connected to GND and a curve
tracer’s collector output drive connected to the input.
SECOND GAIN
INPUT FROM
STAGE
Figure 45. OP284 Equivalent Output Circuit
I1
Q1
R1
R2
I2
Q2
V+
V–
R3
D1
R5
Q3
Q4
R4
R6
Q6
Q5
V
OUT