AD8614ART-REEL7 ,Single Supply 18 V Rail-to-Rail In/Out 70 mA Op AmpCHARACTERISTICS␣I = 10 mA V –0.15 VOutput Voltage High VOH LOAD SOutput Voltage Low V I = 10 mA 65 ..
AD8614ART-REEL7 ,Single Supply 18 V Rail-to-Rail In/Out 70 mA Op Ampfeatures proprietary ESD protection circuitry, permanent dam-age may occur on devices subjected to ..
AD8614ARTZ-REEL , Single and Quad 18 V Operational Amplifiers
AD8614ARTZ-REEL7 ,Single Supply 18 V Rail-to-Rail In/Out 70 mA Op AmpCHARACTERISTICS␣Offset Voltage V 1.0 2.5 mVOS£ +85
AD8614ART-R2-AD8614ART-REEL-AD8614ART-REEL7-AD8614ARTZ-REEL7-AD8644AR-AD8644ARZ
Single Supply 18 V Rail-to-Rail In/Out 70 mA Op Amp
REV.0
Single and Quad +18 V
Operational Amplifiers
PIN CONFIGURATIONS
5-Lead SOT-23
(RT Suffix)
14-Lead TSSOP
(RU Suffix)
14-Lead Narrow Body SO
(R Suffix)
FEATURES
Unity Gain Bandwidth: 5.5 MHz
Low Voltage Offset: 1.0 mV
Slew Rate: 7.5 V/ms
Single-Supply Operation: 5 V to 18 V
High Output Current: 70 mA
Low Supply Current: 800 mA/Amplifier
Stable with Large Capacitive Loads
Rail-to-Rail Inputs and Outputs
APPLICATIONS
LCD Gamma and VCOM Drivers
Modems
Portable Instrumentation
Direct Access Arrangement
GENERAL DESCRIPTIONThe AD8614 (single) and AD8644 (quad) are single-supply,
5.5 MHz bandwidth, rail-to-rail amplifiers optimized for LCD
monitor applications.
They are processed using Analog Devices high voltage, high speed,
complementary bipolar process—HV XFCB. This proprietary
process includes trench isolated transistors that lower internal
parasitic capacitance which improves gain bandwidth, phase mar-
gin and capacitive load drive. The low supply current of 800 mA
(typ) per amplifier is critical for portable or densely packed designs.
In addition, the rail-to-rail output swing provides greater dynamic
range and control than standard video amplifiers provide.
These products operate from supplies of 5 V to as high as
18 V. The unique combination of an output drive of 70 mA,
high slew rates, and high capacitive drive capability makes the
AD8614/AD8644 an ideal choice for LCD applications.
The AD8614 and AD8644 are specified over the temperature
range of –20°C to +85°C. They are available in 5-lead SOT-23,
14-lead TSSOP and 14-lead SOIC surface mount packages in
tape and reel.
AD8614/AD8644–SPECIFICATIONS
ELECTRICAL CHARACTERISTICSNOTE
All typical values are for VS = 18 V.
Specifications subject to change without notice.
(5 V £ VS £ 18 V, VCM = VS/2, TA = 258C unless otherwise noted)
CAUTIONESD (electrostatic discharge) sensitive device. Electrostatic charges as high as 4000V readily
ABSOLUTE MAXIMUM RATINGSSupply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .20 V
Input Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . .GND to VS
Storage Temperature Range . . . . . . . . . . . .–65°C to +150°C
Operating Temperature Range . . . . . . . . . . .–20°C to +85°C
Junction Temperature Range . . . . . . . . . . . .–65°C to +150°C
Lead Temperature Range (Soldering, 60 sec) . . . . . . . .300°C
NOTESStresses above those listed under Absolute Maximum Ratings may cause perma-
nent damage to the device. This is a stress rating only; functional operation of the
device at these or any other conditions above those listed in the operational sections
of this specification is not implied. Exposure to absolute maximum rating condi-
tions for extended periods may affect device reliability.
NOTEqJA is specified for worst-case conditions, i.e., qJA is specified for device soldered
onto a circuit board for surface mount packages.
ORDERING GUIDENOTESAvailable in 3,000 or 10,000 piece reels.Available in 2,500 piece reels only.
Figure 1.Small Signal Overshoot vs.
Load Capacitance
Figure 2.Settling Time
Figure 3.Open-Loop Gain and Phase
vs. Frequency
Figure 4.Large Signal Transient
Response
Figure 5.Large Signal Transient
Response
Figure 6.Small Signal Transient
Response
LOAD CURRENT – mA0.0011000.010.1110
10k
OUTPUT VOLTAGE – mV Figure 7.Output Voltage to Supply
Rail vs. Load Current
SUPPLY VOLTAGE – 6Volts
1,000
SUPPLY CURRENT/AMPLIFIER – Figure 8.Supply Current vs. Supply
Voltage
Figure 9.Input Bias Current vs.
Common-Mode Voltage
AD8614/AD8644
COMMON-MODE VOLTAGE – Volts
400240029
927252321
01357
200100
INPUT BIAS CURRENT – nA
Figure 10.Input Bias Current vs.
Common-Mode Voltage
INPUT OFFSET VOLTAGE – mV200.511.5
QUANTITY – Amplifiers
120 Figure 11.Input Offset Voltage
Distribution
Figure 12.Supply Current vs.
Temperature
FREQUENCY – Hz
OUTPUT SWING – V p-p1001k10M10k100k1M Figure 13.Maximum Output Swing
vs. Frequency
FREQUENCY – Hz
OUTPUT SWING – V p-p1001k10M10k100k1M Figure 14.Maximum Output Swing
vs. Frequency
FREQUENCY –Hz
IMPEDANCE –
2401k10k100k1M10M
120 Figure 15.Closed-Loop Output
Impedance vs. Frequency
FREQUENCY –Hz
GAIN – dB10k100M100k1M10M Figure 16.Closed-Loop Gain vs.
Frequency
FREQUENCY –Hz
COMMON-MODE REJECTION – dB
1001k10M10k100k1M
140 Figure 17.Common-Mode Rejection
vs. Frequency
FREQUENCY – Hz
POWER-SUPPLY REJECTION – dB
1001k10k100k1M
10M Figure 18.Power-Supply Rejection
vs. Frequency
SUPPLY VOLTAGE – V2204681012141618
SLEW RATE – V/ Figure 19.Slew Rate vs. Supply
Voltage
VOLTAGE NOISE DENSITY – nV Hz
FREQUENCY – Hz
1001010010k1k Figure 20.Voltage Noise Density
vs. Frequency
Figure 21.Voltage Noise Density vs.
Frequency
APPLICATIONS SECTION
Theory of OperationThe AD8614/AD8644 are processed using Analog Devices’ high
voltage, high speed, complementary bipolar process—HV XFCB.
This process includes trench isolated transistors that lower parasitic
capacitance.
Figure 22 shows a simplified schematic of the AD8614/AD8644.
The input stage is rail-to-rail, consisting of two complementary
differential pairs, one NPN pair and one PNP pair. The input stage
is protected against avalanche breakdown by two back-to-back
diodes. Each input has a 1.5 kW resistor that limits input current
during over-voltage events and furnishes phase reversal protection
if the inputs are exceeded. The two differential pairs are connected
to a double-folded cascode. This is the stage in the amplifier with
the most gain. The double folded cascode differentially feeds the
output stage circuitry. Two complementary common emitter tran-
sistors are used as the output stage. This allows the output to swing
to within 125 mV from each rail with a 10 mA load. The gain of the
output stage, and thus the open loop gain of the op amp, depends on
the load resistance.
VCC+1.5kV
VCCVOUT
1.5kV
VCCThe AD8614/AD8644 have no built-in short circuit protection.
The short circuit limit is a function of high current roll-off of the
output stage transistors and the voltage drop over the resistor
shown on the schematic at the output stage. The voltage over this
resistor is clamped to one diode during short circuit voltage events.
Output Short-Circuit ProtectionTo achieve a wide bandwidth and high slew rate, the output of
the AD8614/AD8644 is not short-circuit protected. Shorting
the output directly to ground or to a supply rail may destroy the
device. The typical maximum safe output current is 70mA.
In applications where some output current protection is needed,
but not at the expense of reduced output voltage headroom, a low
value resistor in series with the output can be used. This is shown
in Figure 23. The resistor is connected within the feedback loop
of the amplifier so that if VOUT is shorted to ground and VIN
swings up to 18V, the output current will not exceed 70 mA.
For 18V single supply applications, resistors less than 261 W are
not recommended.
AD8614/AD8644Figure 23.Output Short-Circuit Protection
Input Overvoltage ProtectionAs with any semiconductor device, whenever the condition exists for
the input to exceed either supply voltage, attention needs to be paid
to the input overvoltage characteristic. As an overvoltage occurs, the
amplifier could be damaged, depending on the voltage level and the
magnitude of the fault current. When the input voltage exceeds
either supply by more than 0.6 V, internal pin junctions energize,
allowing current to flow from the input to the supplies. Observing
Figure 22, the AD8614/AD8644 has 1.5 kW resistors in series with
each input, which helps limit the current. This input current is not
inherently damaging to the device as long as it is limited to 5 mA or
less. If the voltage is large enough to cause more than 5 mA of cur-
rent to flow, an external series resistor should be added. The size of
this resistor is calculated by dividing the maximum overvoltage by
5 mA and subtracting the internal 1.5 kW resistor. For example, if
the input voltage could reach 100 V, the external resistor should be
(100 V/5 mA) – 1.5 kW = 18.5 kW. This resistance should be placed
in series with either or both inputs if they are subjected to the over-
voltages. For more information on general overvoltage characteristics
of amplifiers refer to the 1993 System Applications Guide, available
from the Analog Devices Literature Center.
Output Phase ReversalThe AD8614/AD8644 is immune to phase reversal as long as the
input voltage is limited to within the supply rails. Although the
device’s output will not change phase, large currents due to
input overvoltage could result, damaging the device. In applica-
tions where the possibility of an input voltage exceeding the
supply voltage exists, overvoltage protection should be used, as
described in the previous section.
Power DissipationThe maximum power that can be safely dissipated by the
AD8614/AD8644 is limited by the associated rise in junction
temperature. The maximum safe junction temperature is 150°C,
and should not be exceeded or device performance could suffer.
If this maximum is momentarily exceeded, proper circuit opera-
tion will be restored as soon as the die temperature is reduced.
Leaving the device in an “overheated” condition for an extended
period can result in permanent damage to the device.
To calculate the internal junction temperature of the AD86x4,
the following formula can be used:
TJ = PDISS · qJA + TA
where:TJ = AD86x4 junction temperature;
PDISS = AD86x4 power dissipation;JA = AD86x4 package thermal resistance, junction-to-
ambient; and
The power dissipated by the device can be calculated as:
PDISS = ILOAD · (VS – VOUT)
where:ILOAD is the AD86x4 output load current;
VS is the AD86x4 supply voltage; and
VOUT is the AD86x4 output voltage.
Figure 24 provides a convenient way to see if the device is being
overheated. The maximum safe power dissipation can be found
graphically, based on the package type and the ambient tem-
perature around the package. By using the previous equation, it
is a simple matter to see if PDISS exceeds the device’s power
derating curve. To ensure proper operation, it is important to
observe the recommended derating curves shown in Figure 24.
AMBIENT TEMPERATURE – 8C
MAXIMUM POWER DISSIPATION – WattsFigure 24.Maximum Power Dissipation vs. Temperature
for 5-Lead and 14-Lead Package Types
Unused AmplifiersIt is recommended that any unused amplifiers in the quad pack-
age be configured as a unity gain follower with a 1kW feedback
resistor connected from the inverting input to the output, and
the noninverting input tied to the ground plane.
Capacitive Load DriveThe AD8614/AD8644 exhibits excellent capacitive load driving
capabilities. Although the device is stable with large capacitive
loads, there is a decrease in amplifier bandwidth as the capacitive
load increases.
When driving heavy capacitive loads directly from the AD8614/
AD8644 output, a snubber network can be used to improve the
transient response. This network consists of a series R-C connected
from the amplifier’s output to ground, placing it in parallel with the
capacitive load. The configuration is shown in Figure 25. Although
this network will not increase the bandwidth of the amplifier, it will
significantly reduce the amount of overshoot.
