REV. D
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties that
may result from its use. No license is granted by implication or otherwise
under any patent or patent rights of Analog Devices.
a
Fast, Precision
Comparator
AD790
FEATURES
45 ns max Propagation Delay
Single 5 V or Dual ⴞ15 V Supply Operation
CMOS or TTL Compatible Output
250 V max Input Offset Voltage
500 V max Input Hysteresis Voltage
15 V max Differential Input Voltage
Onboard Latch
60 mW Power Dissipation
Available in 8-Pin Plastic and Hermetic Cerdip
Packages
Available in Tape and Reel in Accordance with
EIA-481A Standard
APPLICATIONS
Zero-Crossing Detectors
Overvoltage Detectors
Pulse-Width Modulators
Precision Rectifiers
Discrete A/D Converters
Delta-Sigma Modulator A/Ds
PRODUCT DESCRIPTION
The AD790 is a fast (45 ns), precise voltage comparator, with a
number of features that make it exceptionally versatile and easy
to use. The AD790 may operate from either a single 5 V supply
or a dual ±15 V supply. In the single-supply mode, the AD790’s
inputs may be referred to ground, a feature not found in other
comparators. In the dual-supply mode it has the unique ability
of handling a maximum differential voltage of 15 V across its in-
put terminals, easing their interfacing to large amplitude and
dynamic signals.
This device is fabricated using Analog Devices’ Complementary
Bipolar (CB) process—which gives the AD790’s combination
of fast response time and outstanding input voltage resolution
(1 mV max). To preserve its speed and accuracy, the AD790
incorporates a “low glitch” output stage that does not exhibit
the large current spikes normally found in TTL or CMOS output
stages. Its controlled switching reduces power supply disturbances
that can feed back to the input and cause undesired oscillations.
The AD790 also has a latching function which makes it suitable
for applications requiring synchronous operation.
The AD790 is available in five performance grades. The
AD790J and the AD790K are rated over the commercial tem-
perature range of 0°C to 70°C. The AD790A and AD790B are
rated over the industrial temperature range of –40°C to +85°C.
The AD790S is rated over the military temperature range of
–55°C to +125°C.
PRODUCT HIGHLIGHTS
1. The AD790’s combination of speed, precision, versatility
and low cost makes it suitable as a general purpose compara-
tor in analog signal processing and data acquisition systems.
2. Built-in hysteresis and a low-glitch output stage minimize the
chance of unwanted oscillations, making the AD790 easier to
use than standard open-loop comparators.
3. The hysteresis combined with a wide input voltage range
enables the AD790 to respond to both slow, low level (e.g.,
10 mV) signals and fast, large amplitude (e.g., 10 V) signals.
4. A wide variety of supply voltages is acceptable for operation
of the AD790, ranging from single 5 V to dual +5 V/–12 V,
±5 V, or +5 V/±15 V supplies.
5. The AD790’s power dissipation is the lowest of any compara-
tor in its speed range.
6. The AD790’s output swing is symmetric between V
LOGIC
and ground, thus providing a predictable output under a
wide range of input and output conditions.
CONNECTION DIAGRAMS
8-Pin Plastic Mini-DIP (N)
and Cerdip (Q) Packages
OUTPUT
LATCH
GROUND
VLOGIC
1
2
3
45
6
7
8
AD790
–
+
+VS
+IN
–IN
–VS
8-Pin SOIC (R) Package
LATCH
GROUND
V
LOGIC
+V
S
1
2
3
45
6
7
8
OUTPUT AD790
+
–
+IN –IN
–V
S
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700www.analog.com
Fax: 781/326-8703 © Analog Devices, Inc., 2002
REV. D
–2–
AD790–SPECIFICATIONS
DUAL SUPPLY
AD790J/A AD790K/B AD790S
Parameter Conditions Min Typ Max Min Typ Max Min Typ Max Unit
RESPONSE CHARACTERISTIC 100 mV Step
Propagation Delay, t
PD
5 mV Overdrive 40 45 40 45 40 45 ns
T
MIN
to T
MAX
45/50 45/50 60 ns
OUTPUT CHARACTERISTICS
Output HIGH Voltage, V
OH
1.6 mA Source 4.65 4.65 4.65
6.4 mA Source 4.3 4.45 4.3 4.45 4.3 4.45 V
T
MIN
to T
MAX
4.3/4.3 4.3 4.3 V
Output LOW Voltage, V
OL
1.6 mA Sink 0.35 0.35 0.35 V
6.4 mA Sink 0.44 0.5 0.44 0.5 0.44 0.5 V
T
MIN
to T
MAX
0.5/0.5 0.5 0.5 V
INPUT CHARACTERISTICS
Offset Voltage
1
0.2 1.0 0.05 0.25 0.2 1.0 mV
T
MIN
to T
MAX
1.5 0.5 1.5 mV
Hysteresis
2
T
MIN
to T
MAX
0.3 0.4 0.6 0.3 0.4 0.5 0.3 0.4 0.65 mV
Bias Current Either Input 2.5 5 1.8 3.5 2.5 5µA
T
MIN
to T
MAX
6.5 4.5 7 µA
Offset Current 0.04 0.25 0.02 0.15 0.04 0.25 µA
T
MIN
to T
MAX
0.3 0.2 0.4 µA
Power Supply
Rejection Ratio DC V
S
±20% 80 90 88 100 80 90 dB
T
MIN
to T
MAX
76 88 85 93 76 85 dB
Input Voltage Range
Differential Voltage V
S
≤± 15 V ⴞV
S
ⴞV
S
ⴞV
S
V
Common Mode –V
S
+V
S
–2 V –V
S
+V
S
–2 V –V
S
+V
S
–2 V V
Common Mode
Rejection Ratio –10 V<V
CM
80 95 88 105 80 95 dB
<+10 V
T
MIN
to T
MAX
76 90 85 100 76 88 dB
Input Impedance 20储220储220储2MΩ储pF
LATCH CHARACTERISTICS
Latch Hold Time, t
H
25 35 25 35 25 35 ns
Latch Setup Time, t
S
510 510 510 ns
LOW Input Level, V
IL
T
MIN
to T
MAX
0.8 0.8 0.8 V
HIGH Input Level, V
IH
T
MIN
to T
MA X
1.6 1.6 1.6 V
Latch Input Current 2.3 5 2.3 3.5 2.3 5µA
T
MIN
to T
MAX
758µA
SUPPLY CHARACTERISTICS
Diff Supply Voltage
3
V
LOGIC
= 5 V
T
MIN
to T
MAX
4.5 33 4.5 33 4.7 33 V
Logic Supply T
MIN
to T
MAX
4.0 7 4.0 7 4.2 7 V
Quiescent Current
+V
S
+V
S
= 15 V 8 10 810 810 mA
–V
S
–V
S
= –15 V 4 54545mA
V
LOGIC
V
LOGIC
= 5 V 2 3.3 23.3 23.3 mA
Power Dissipation 242 242 242 mW
TEMPERATURE RANGE
Rated Performance T
MIN
to T
MAX
0 to 70/–40 to +85 0 to 70/–40 to +85 –55 to +125 °C
NOTES
1
Defined as the average of the input voltages at the low to high and high to low transition points. Refer to Figure 6.
2
Defined as half the magnitude between the input voltages at the low to high and high to low transition points. Refer to Figure 6.
3
+V
S
must be no lower than (V
LOGIC
–0.5 V) in any supply operating conditions, except during power up.
All min and max specifications are guaranteed. Specifications shown in boldface are tested on all production units at final test.
Specifications subject to change without notice.
(Operation @ 25ⴗC and +VS = 15 V, –VS = –15 V, VLOGIC = 5 V unless otherwise noted.)
SINGLE SUPPLY
AD790J/A AD790K/B AD790S
Parameter Conditions Min Typ Max Min Typ Max Min Typ Max Unit
RESPONSE CHARACTERISTIC 100 mV Step
Propagation Delay, t
PD
5 mV Overdrive 45 50 45 50 45 50 ns
T
MIN
to T
MAX
50/60 50/60 65 ns
OUTPUT CHARACTERISTICS
Output HIGH Voltage, V
OH
1.6 mA Source 4.65 4.65 4.65
6.4 mA Source 4.3 4.45 4.3 4.45 4.3 4.45 V
T
MIN
to T
MAX
4.3 4.3 4.3 V
Output LOW Voltage, V
OL
1.6 mA Sink 0.35 0.35 0.35 V
6.4 mA Sink 0.44 0.5 0.44 0.5 0.44 0.5 V
T
MIN
to T
MAX
0.5 0.5 0.5 V
INPUT CHARACTERISTICS
Offset Voltage
2
0.45 1.5 0.35 0.6 0.45 1.5 mV
T
MIN
to T
MAX
2.0 0.85 2.0 mV
Hysteresis
3
T
MIN
to T
MAX
0.3 0.5 0.75 0.3 0.5 0.65 0.3 0.7 1.0 mV
Bias Current Either Input 2.7 5 2.0 3.5 2.7 5µA
T
MIN
to T
MAX
758µA
Offset Current 0.04 0.25 0.02 0.15 0.04 0.25 µA
T
MIN
to T
MAX
0.3 0.2 0.4 µA
Power Supply
Rejection Ratio DC 4.5 V≤V
S
≤5.5 V 80 90 86 100 80 90 dB
T
MIN
to T
MAX
76/76 88 82 93 76 85 dB
Input Voltage Range
Differential Voltage ⴞV
S
ⴞV
S
ⴞV
S
V
Common Mode 0 +V
S
–2 V 0 +V
S
–2 V 0 +V
S
–2 V V
Input Impedance 20储220储220储2MΩ储pF
LATCH CHARACTERISTICS
Latch Hold Time, t
H
25 35 25 35 25 35 ns
Latch Setup Time, t
S
510 510 510 ns
LOW Input Level, V
IL
T
MIN
to T
MAX
0.8 0.8 0.8 V
HIGH Input Level, V
IH
T
MIN
to T
MAX
1.6 1.6 1.6 V
Latch Input Current 2.3 52.3 3.5 2.3 5µA
T
MIN
to T
MAX
758µA
SUPPLY CHARACTERISTICS
Supply Voltage
4
T
MIN
to T
MAX
4.5 7 4.5 7 4.7 7 V
Quiescent Current 10 12 10 12 10 12 mA
Power Dissipation 60 60 60 mW
TEMPERATURE RANGE
Rated Performance T
MIN
to T
MAX
0 to 70/–40 to +85 0 to 70/–40 to +85 –55 to +125 °C
NOTES
1
Pin 1 tied to Pin 8, and Pin 4 tied to Pin 6.
2
Defined as the average of the input voltages at the low to high and high to low transition points. Refer to Figure 6.
3
Defined as half the magnitude between the input voltages at the low to high and high to low transition points. Refer to Figure 6.
4
–V
S
must not be connected above ground.
All min and max specifications are guaranteed. Specifications shown in boldface are tested on all production units at final test.
Specifications subject to change without notice.
AD790
REV. D –3–
(Operation @ 25ⴗC and +VS = VLOGIC = 5 V, –VS = 0 V unless otherwise noted.)1
AD790
REV. D
–4–
ABSOLUTE MAXIMUM RATINGS
1, 2
Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±18 V
Internal Power Dissipation
2
. . . . . . . . . . . . . . . . . . . 500 mW
Differential Input Voltage . . . . . . . . . . . . . . . . . . . . . ±16.5 V
Output Short-Circuit Duration . . . . . . . . . . . . . . . . Indefinite
Storage Temperature Range
(N, R) . . . . . . . . . . . . . . . . . . . . . . . . . . . –65°C to +125°C
(Q) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . –65°C to +150°C
Lead Temperature Range (Soldering 60 sec) . . . . . . . . 300°C
Logic Supply Voltage . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 V
NOTES
1
Stresses above those listed under “Absolute Maximum Ratings” may cause perma-
nent damage to the device. This is a stress rating only and functional operation of
the device at these or any other conditions above those indicated in the operational
sections of this specification is not implied. Exposure to absolute maximum rating
conditions for extended periods may affect device reliability.
2
Thermal characteristics: plastic N-8 package: θ
JA
= 90°C/watt; ceramic Q-8
package: θ
JA
= 110°C/watt, θ
JC
= 30°C/watt. SOIC (R-8) package: θ
JA
= 160°C
watt; θ
JC
= 42°C/watt.
AD790
0.1µF
0.1µF
0.1µF
15V
+
+IN
–IN
5V
+
510
OUTPUT
15V
–
LATCH
(OPTIONAL)
8
1
5
7
6
4
3
2
Ω
Figure 1. Basic Dual Supply
Configuration (N, Q Package Pinout)
AD790
1
2
3
4
5
6
7
8
+5V
+15V
–15V
TEK
7904
SCOPE
–5V
VOLTAGE
SOURCE
10Ω
–5mV
0.1µF
–100mV
–1.3V
–1.7V
–5V
HP8112
PULSE
GENERATOR
1k
HP2835
MPS
571 0.1µF
0.1µF
0.1µF
10kΩ
650Ω 400Ω 50Ω
25Ω
130Ω
Figure 3. Response Time Test Circuit (N, Q Package Pinout)
ORDERING GUIDE
Temperature Package Package
Model Range Description Option
AD790JN 0°C to 70°CPlastic DIP N-8
AD790JR 0°C to 70°CSOIC SO-8
AD790JR-REEL 0°C to 70°CReel
AD790JR-REEL7 0°C to 70°CSOIC R-8
AD790KN
*
0°C to 70°CPlastic DIP N-8
AD790AQ –40°C to +85°CCerdip Q-8
AD790BQ
*
–40°C to +85°CCerdip Q-8
AD790SQ –55°C to +125°CCerdip Q-8
*
Not for new designs; obsolete April 2002.
For military processed devices, please refer to the standard Mi-
crocircuit Drawing (SMD) available at
www.dscc.dla.mil/programs/milspec/default.asp
SMD Part Number ADI Equivalent
5962-9150501MPA
*
AD790 SQ/883
*
Not for new designs; obsolete April 2002.
AD790
1
2
3
4
5
6
7
8
0.1µF
+IN
–
IN
5V
+
OUTPUT
LATCH
(OPTIONAL)
510Ω
Figure 2. Basic Single Supply
Configuration (N, Q Package Pinout)
Typical Performace Characteristics–AD790
REV. D –5–
TPC 2. Propagation Delay vs.
Load Capacitance
TPC 5. Propagation Delay vs.
Temperature
TPC 8. Total Supply Current vs.
Temperature
TPC 3. Propagation Delay vs.
Fanout (LSTTL and CMOS)
06410
0.8
0.7
0.6
0.5
0.4
0.2
0.1
0.3
0.0 28
I
SINK
– mA
TEMP = +25°C
OUTPUT LOW VOLTAGE – Volts
TPC 6. Output Low Voltage vs.
Sink Current
INPUT
tH
LATCH
tS
OUTPUT
tPD
0
VIH
VIL
VOH
VOL
tS = SETUP TIME
tH = HOLD TIME
tPD = COMPARATOR RESPONSE TIME
Figure 4. Latch Timing
TPC 1. Propagation Delay vs.
Overdrive
TPC 4. Propagation Delay vs.
Source Resistance
06410
5.0
4.9
4.8
4.7
4.6
4.4
4.3
4.5
4.2
28
TEMP = +25°C
OUTPUT LOW VOLTAGE – Volts
ISOURCE – mA
TPC 7. Output High Voltage vs.
Source Current
AD790
REV. D
–6–
CIRCUIT DESCRIPTION
The AD790 possesses the overall characteristics of a standard
monolithic comparator: differential inputs, high gain and a logic
output. However, its function is implemented with an architec-
ture which offers several advantages over previous comparator
designs. Specifically, the output stage alleviates some of the limi-
tations of classic “TTL” comparators and provides a symmetric
output. A simplified representation of the AD790 circuitry is
shown in Figure 5.
A1
A2
Av OUTPUT
GAIN STAGE OUTPUT STAGE
Q2
Q1
–
+
–
+
–
+
IN
+
IN
–
VLOGIC
GND
Figure 5. AD790 Block Diagram
The output stage takes the amplified differential input signal and
converts it to a single-ended logic output. The output swing is
defined by the pull-up PNP and the pull-down NPN. These pro-
duce inherent rail-to-rail output levels, compatible with CMOS
logic, as well as TTL, without the need for clamping to internal
bias levels. Furthermore, the pull-up and pull-down levels are
symmetric about the center of the supply range and are refer-
enced off the V
LOGIC
supply and ground. The output stage has
nearly symmetric dynamic drive capability, yielding equal rise
and fall times into subsequent logic gates.
Unlike classic TTL or CMOS output stages, the AD790 circuit
does not exhibit large current spikes due to unwanted current
flow between the output transistors. The AD790 output stage
has a controlled switching scheme in which amplifiers A1 and
A2 drive the output transistors in a manner designed to reduce
the current flow between Q1 and Q2. This also helps minimize
the disturbances feeding back to the input which can cause
troublesome oscillations.
The output high and low levels are well controlled values defined
by V
LOGIC
(5 V), ground and the transistor equivalent Schottky
clamps and are compatible with TTL and CMOS logic require-
ments. The fanout of the output stage is shown in TPC 3 for
standard LSTTL or HCMOS gates. Output drive behavior vs.
capacitive load is shown in TPC 2.
HYSTERESIS
The AD790 uses internal feedback to develop hysteresis about
the input reference voltage. Figure 6 shows how the input offset
voltage and hysteresis terms are defined. Input offset voltage
(V
OS
) is the difference between the center of the hysteresis
range and the ground level. This can be either positive or nega-
tive. The hysteresis voltage (V
H
) is one-half the width of the
V
OH
V
OL
H
V
= HYSTERESIS VOLTAGE
H
V
0
H
V
V
OUT
IN
+
V
OS
V
OS
= INPUT OFFSET VOLTAGE 2
3
7
IN
+
OUT
V
GND
Figure 6. Hysteresis Definitions (N, Q Package Pinout)
hysteresis range. This built-in hysteresis allows the AD790 to
avoid oscillation when an input signal slowly crosses the ground
level.
SUPPLY VOLTAGE CONNECTIONS
The AD790 may be operated from either single or dual supply
voltages. Internally, the V
LOGIC
circuitry and the analog front-
end of the AD790 are connected to separate supply pins. If dual
supplies are used, any combination of voltages in which +V
S
≥
V
LOGIC
– 0.5 V and –V
S
≤ 0 may be chosen. For single supply
operation (i.e., +V
S
= V
LOGIC
), the supply voltage can be oper-
ated between 4.5 V and 7 V. Figure 7 shows some other examples
of typical supply connections possible with the AD790.
BYPASSING AND GROUNDING
Although the AD790 is designed to be stable and free from
oscillations, it is important to properly bypass and ground the
power supplies. Ceramic 0.1 µF capacitors are recommended
and should be connected directly at the AD790’s supply pins.
These capacitors provide transient currents to the device during
comparator switching. The AD790 has three supply voltage
pins, +V
S
, –V
S
and V
LOGIC
. It is important to have a common
ground lead on the board for the supply grounds and the GND
pin of the AD790 to provide the proper return path for the
supply current.
LATCH OPERATION
The AD790 has a latch function for retaining input information
at the output. The comparator decision is “latched” and the
output state is held when Pin 5 is brought low. As long as Pin 5
is kept low, the output remains in the high or low state, and
does not respond to changing inputs. Proper capture of the
input signal requires that the timing relationships shown in
Figure 4 are followed. Pin 5 should be driven with CMOS or
TTL logic levels.
The output of the AD790 will respond to the input when Pin 5
is at a high logic level. When not in use, Pin 5 should be connected
to the positive logic supply. When using dual supplies, it is rec-
ommended that a 510 Ω resistor be placed in series with Pin 5
and the driving logic gate to limit input currents during powerup.
AD790
REV. D –7–
AD790
1
2
3
4
5
6
7
8
+IN
–IN
5V
+
OUT
510Ω
+12V
0.1µF
0.1µF
+V
S
= +12V, –V
S
= 0V
V
LOGIC
= +5V
AD790
1
2
3
4
5
6
7
8
5V
+
OUT
15V
–
0.1µF
0.1µF
+V
S
= +5V, –V
S
= –15V
V
LOGIC
= +5V
+IN
–IN
AD790
1
2
3
4
5
6
7
8
5V
+
OUT
5V
–
0.1µF
0.1µF
+IN
–IN
+V
S
= +5V, –V
S
= –5V, V
LOGIC
= +5V
Figure 7. Typical Power Supply Connections
(N, Q Package Pinout)
Window Comparator for Overvoltage Detection
The wide differential input range of the AD790 makes it suitable
for monitoring large amplitude signals. The simple overvoltage
detection circuit shown in Figure 8 illustrates direct connection
of the input signal to the high impedance inputs of the comparator
without the need for special clamp diodes to limit the differen-
tial
input voltage across the inputs.
510Ω
OVERRANGE = 1
7432
AD790
1
2
3
4
5
6
7
8
+15V
+5V
–15V
AD790
1
2
3
4
5
6
7
8
+15V +5V
–15V
VIN
510Ω
0.1µF 0.1µF
0.1µF
0.1µF
0.1µF
0.1µF
SIGN 1 = HIGH
0 = LOW
–7.5V
+7.5V
Figure 8. Overvoltage Detector
(N, Q Package Pinout)
Single Supply Ground Referred Overload Detector
The AD790 is useful as an overload detector for sensitive loads
that must be powered from a single supply. A simple ground
referenced overload detector is shown in Figure 8. The com-
parator senses a voltage across a PC board trace and compares
that to a reference (trip) voltage established by the comparator’s
minus supply current through a 2.7 Ω resistor. This sets up a
10 mV reference level that is compared to the sense voltage.
Applying the
–7–
The minus supply current is proportional to absolute tempera-
ture and compensates for the change in the sense resistance
with temperature. The width and length of the PC board trace
determine the resistance of the trace and consequently the trip
current level.
I
LIMIT
= 10 mV/R
SENSE
R
SENSE
= rho (trace length/trace width)
rho = resistance of a unit square of trace
L
O
A
D
2.7
PC BOARD
TRACE
AD790
1
2
3
4
5
6
7
8
0.1µF
5V
+
OUTPUT
R
SENSE
≈ 10mV/100mA
+V
S
510Ω
Ω
Figure 9. Ground Referred Overload Detector Circuit
(N, Q Package Pinout)
Precision Full-Wave Rectifier
The high speed and precision of the AD790 make it suitable
for use in the wide dynamic range full-wave rectifier shown in
Figure 10. This circuit is capable of rectifying low level signals
as small as a few mV or as high as 10 V. Input resolution, propaga-
tion delay and op amp settling will ultimately limit the maximum
input frequency for a given accuracy level. Total comparator
plus switch delay is approximately 100 ns, which limits the
maximum input frequency to 1 MHz for clean rectification.
AD711
10k
FET SWITCHES THE GAIN
FROM +1 TO –1
20k
10k
AD790
1
2
3
4
5
6
7
8
+15V
+5V
–15V
2
34
6
7
+15V
–15V
VIN VOUT
NMOS
FET
(RON < 20 )
0.1µF
510
0.1µF
0.1µF
0.1µF
0.1µF
Ω
Ω
Ω
Ω
Ω
Figure 10. Precision Full-Wave Rectifier
(N, Q Package Pinout)
AD790
REV. D
–8–
2
3
1
4
6
7
5
8
TTL
LEVEL
OUTPUT
400 *
5V
+
GND
STANDARD
SCHOTTKY
DIODE
1k
A RESISTOR UP TO 10k MAYBE USED TO
REDUCE THE SOURCE AND SINK CURRENT OF
THE DRIVER. HOWEVER, THIS WILL SLIGHTLY
LOWER THE MAXIMUM USABLE CLOCK RATE.
*
BIPOLAR
SIGNAL
INPUT
4.7V
0.3V
5V
–
Ω
Ω
Ω
Figure 11. A Bipolar to CMOS TTL Line Receiver (N, Q
Package Pinout)
Bipolar to CMOS/TTL
It is sometimes desirable to translate a bipolar signal (e.g.,
±5 V) coming from a communications cable or another section
of the system to CMOS/TTL logic levels; such an application is
referred to as a line receiver. Previously, the interface to the
bipolar signal required either a dual (±) power supply or a refer-
ence voltage level about which the line receiver would switch.
The AD790 may be used in a simple circuit to provide a unique
capability: the ability to receive a bipolar signal while powered
from a single 5 V supply. Other comparators cannot perform
this task. Figure 11 shows a 1 kΩ resistor in series with the input
signal which is then clamped by a Schottky diode, holding the
input of the comparator at 0.4 V below ground. Although the
comparator is specified for a common mode range down to –V
S
,
(in this case ground) it is permissible to bring one of the inputs
a few hundred mV below ground. The comparator switches
around this level and produces a CMOS/TTL compatible swing.
The circuit will operate to switching frequencies of 20 MHz.
AD790
REV. D –9–
OUTLINE DIMENSIONS
Dimensions shown in inches and (mm).
8-Pin Plastic Mini-DIP (N-8) Package 8-Pin Cerdip (Q-8) Package
SOIC (R-8) Package
0.25 (0.0098)
0.19 (0.0075)
1.27 (0.0500)
0.41 (0.0160)
0.50 (0.0196)
0.25 (0.0099) ⴛ 45ⴗ
8ⴗ
0ⴗ
1.75 (0.0688)
1.35 (0.0532)
SEATING
PLANE
0.25 (0.0098)
0.10 (0.0040)
85
41
5.00 (0.1968)
4.80 (0.1890)
PIN 1
0.1574 (4.00)
0.1497 (3.80)
1.27 (0.0500)
BSC
6.20 (0.2440)
5.80 (0.2284)
0.51 (0.0201)
0.33 (0.0130)
COPLANARITY
CONTROLLING DIMENSIONS ARE IN MILLIMETERS; INCH DIMENSIONS
(IN PARENTHESES) ARE ROUNDED-OFF MILLIMETER EQUIVALENTS FOR
REFERENCE ONLY AND ARE NOT APPROPRIATE FOR USE IN DESIGN
COMPLIANT TO JEDEC STANDARDS MS-012 AA
AD790
REV. D
–10–
Revision History
Location Page
Data Sheet changed from REV. C to REV. D.
Edits to SOIC (R-8) Package . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
03/02
—
Data Sheet changed from REV. B to REV. C.
Edits to FEATURES . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Edits to PRODUCT DESCRIPTION . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1
Deleted METALIZATION PHOTOGRAPH . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
Edits to ORDERING GUIDE . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4
–11–
C00844–0–5/02(D)
PRINTED IN U.S.A.
–12–
