a
FEATURES
45 ns max Propagation Delay
Single 5 V or Dual 15 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
+V
S
+IN
–IN
–V
S
1
Fast, Precision
Comparator
AD790
CONNECTION DIAGRAMS
8-Pin Plastic Mini-DIP (N)
and Cerdip (Q) Packages
8
AD790
2
3
4
V
LOGIC
OUTPUT
GROUND
LATCH
+
–
7
6
5
8-Pin SOIC (R) Package
1
2
GROUND
LATCH
–V
S
–IN
OUTPUT
V
LOGIC
+V
S
+IN
AD790
8
7
4
+
3
–
6
5
PRODUCT DESCRIPTION
PRODUCT HIGHLIGHTS
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.
REV.
E
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.
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.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700
www.analog.com
Fax:
781/461-3113
© Analog Devices, Inc.,
2014
AD790–SPECIFICATIONS
DUAL SUPPLY
Parameter
RESPONSE CHARACTERISTIC
Propagation Delay, t
PD
OUTPUT CHARACTERISTICS
Output HIGH Voltage, V
OH
(Operation @ 25 C and +V
S
= 15 V, –V
S
= –15 V, V
LOGIC
= 5 V unless otherwise noted.)
Conditions
100 mV Step
5 mV Overdrive
T
MIN
to T
MAX
1.6 mA Source
6.4 mA Source
T
MIN
to T
MAX
1.6 mA Sink
6.4 mA Sink
T
MIN
to T
MAX
Min
AD790J/A
Typ Max
40
45
45/50
Min
AD790K/B
Typ Max
40
45
45/50
AD790S
Min Typ Max
40
45
60
Unit
ns
ns
4.3
4.3/4.3
4.65
4.45
0.35
0.44
4.3
4.3
0.5
0.5/0.5
1.0
1.5
0.6
5
6.5
0.25
0.3
4.65
4.45
0.35
0.44
4.3
4.3
0.5
0.5
0.25
0.5
0.5
3.5
4.5
0.15
0.2
4.65
4.45
0.35
0.44
Output LOW Voltage, V
OL
0.5
0.5
1.0
1.5
0.65
5
7
0.25
0.4
V
V
V
V
V
mV
mV
mV
µA
µA
µA
µA
dB
dB
INPUT CHARACTERISTICS
Offset Voltage
1
Hysteresis
2
Bias Current
Offset Current
T
MIN
to T
MAX
Power Supply
Rejection Ratio DC
Input Voltage Range
Differential Voltage
Common Mode
Common Mode
Rejection Ratio
V
S
±
20%
T
MIN
to T
MAX
V
S
≤±
15 V
–V
S
–10 V<V
CM
<+10 V
T
MIN
to T
MAX
80
76
80
76
T
MIN
to T
MAX
T
MIN
to T
MAX
Either Input
T
MIN
to T
MAX
0.3
0.2
0.4
2.5
0.04
0.05
0.3
0.4
1.8
0.02
0.2
0.3
0.4
2.5
0.04
90
88
V
S
+V
S
–2 V
95
90
20 2
25
5
35
10
0.8
88
85
100
93
80
76
V
S
+V
S
–2 V –V
S
90
85
–V
S
88
85
105
100
20 2
25
5
1.6
V
S
V
+V
S
–2 V V
95
88
20 2
25
5
35
10
0.8
5
8
dB
dB
MΩ pF
ns
ns
V
V
µA
µA
80
76
Input Impedance
LATCH CHARACTERISTICS
Latch Hold Time, t
H
Latch Setup Time, t
S
LOW Input Level, V
IL
HIGH Input Level, V
IH
Latch Input Current
SUPPLY CHARACTERISTICS
Diff Supply Voltage
3
Logic Supply
Quiescent Current
+V
S
–V
S
V
LOGIC
Power Dissipation
TEMPERATURE RANGE
Rated Performance
T
MIN
to T
MAX
T
MIN
to T
MA X
T
MIN
to T
MAX
V
LOGIC
= 5 V
T
MIN
to T
MAX
T
MIN
to T
MAX
+V
S
= 15 V
–V
S
= –15 V
V
LOGIC
= 5 V
35
10
0.8
1.6
3.5
5
1.6
2.3
5
7
2.3
2.3
4.5
4.0
8
4
2
33
7
10
5
3.3
242
4.5
4.0
8
4
2
33
7
10
5
3.3
242
4.7
4.2
8
4
2
33
7
10
5
3.3
242
V
V
mA
mA
mA
mW
°C
T
MIN
to T
MAX
0 to 70/–40 to +85
0 to 70/–40 to +85
–55 to +125
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.
–2–
REV.
E
AD790
SINGLE SUPPLY
Parameter
RESPONSE CHARACTERISTIC
Propagation Delay, t
PD
OUTPUT CHARACTERISTICS
Output HIGH Voltage, V
OH
(Operation @ 25 C and +V
S
= V
LOGIC
= 5 V, –V
S
= 0 V unless otherwise noted.)
1
Conditions
100 mV Step
5 mV Overdrive
T
MIN
to T
MAX
1.6 mA Source
6.4 mA Source
T
MIN
to T
MAX
1.6 mA Sink
6.4 mA Sink
T
MIN
to T
MAX
AD790J/A
Min Typ Max
45
50
50/60
AD790K/B
Min Typ Max
45
50
50/60
AD790S
Min Typ Max
45
50
65
Unit
ns
ns
4.3
4.3
4.65
4.45
0.35
0.44
4.3
4.3
0.5
0.5
1.5
2.0
0.75
5
7
0.25
0.3
4.65
4.45
0.35
0.44
4.3
4.3
0.5
0.5
0.6
0.85
0.65
3.5
5
0.15
0.2
4.65
4.45
0.35
0.44
Output LOW Voltage, V
OL
0.5
0.5
1.5
2.0
1.0
5
8
0.25
0.4
V
V
V
V
V
mV
mV
mV
µA
µA
µA
µA
dB
dB
INPUT CHARACTERISTICS
Offset Voltage
2
Hysteresis
3
Bias Current
Offset Current
T
MIN
to T
MAX
Power Supply
Rejection Ratio DC
Input Voltage Range
Differential Voltage
Common Mode
Input Impedance
LATCH CHARACTERISTICS
Latch Hold Time, t
H
Latch Setup Time, t
S
LOW Input Level, V
IL
HIGH Input Level, V
IH
Latch Input Current
SUPPLY CHARACTERISTICS
Supply Voltage
4
Quiescent Current
Power Dissipation
TEMPERATURE RANGE
Rated Performance
4.5 V≤V
S
≤5.5
V
T
MIN
to T
MAX
T
MIN
to T
MAX
T
MIN
to T
MAX
Either Input
T
MIN
to T
MAX
0.3
0.45
0.5
2.7
0.04
0.35
0.3
0.5
2.0
0.02
0.45
0.3
0.7
2.7
0.04
80
90
76/76 88
V
S
+V
S
–2 V
20 2
25
5
35
10
0.8
86
82
100
93
80
76
V
S
+V
S
–2 V 0
90
85
0
0
20 2
25
5
1.6
20 2
35
10
0.8
1.6
3.5
5
7
12
60
4.7
10
25
5
V
S
V
+V
S
–2 V V
MΩ pF
35
10
0.8
5
8
7
12
60
ns
ns
V
V
µA
µA
V
mA
mW
°C
T
MIN
to T
MAX
T
MIN
to T
MAX
T
MIN
to T
MAX
T
MIN
to T
MAX
1.6
2.3
5
7
7
12
60
2.3
2.3
4.5
10
4.5
10
T
MIN
to T
MAX
0 to 70/–40 to +85
0 to 70/–40 to +85
–55 to +125
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.
REV.
E
–3–
AD790
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.
+ 15V
0.1µF
+ 5V
0.1µF
LATCH
(OPTIONAL)
+ 5V
0.1µF
LATCH
(OPTIONAL)
510
Ω
1
+IN
2
8
5
+IN
2
1
8
510Ω
AD790
–IN
3
4
6
7
OUTPUT
5
AD790
–IN
3
4
6
7
OUTPUT
0.1µF
– 15V
Figure 1. Basic Dual Supply
Configuration (N, Q Package Pinout)
Figure 2. Basic Single Supply
Configuration (N, Q Package Pinout)
0.1µF
+15V
+5V
0.1µF
–100mV
2
130Ω
25Ω
3
1
8
5
1k
TEK
7904
SCOPE
AD790
6
4
7
0.1µF
–1.3V
PULSE
GENERATOR
–1.7V
MPS
571
0.1µF
–15V
HP8112
HP2835
50Ω
400Ω
650Ω
–5mV
–5V
10Ω
10kΩ
– 5V
VOLTAGE
SOURCE
Figure 3. Response Time Test Circuit (N, Q Package Pinout)
–4–
REV.
E
Typical Performace Characteristics–AD790
TPC 1. Propagation Delay vs.
Overdrive
TPC 2. Propagation Delay vs.
Load Capacitance
TPC 3. Propagation Delay vs.
Fanout (LSTTL and CMOS)
0.8
OUTPUT LOW VOLTAGE – Volts
0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
TEMP = +25°C
0
2
4
6
8
10
I
SINK
– mA
TPC 4. Propagation Delay vs.
Source Resistance
TPC 5. Propagation Delay vs.
Temperature
TPC 6. Output Low Voltage vs.
Sink Current
t
H
5.0
OUTPUT LOW VOLTAGE – Volts
INPUT
0
4.9
4.8
4.7
4.6
4.5
4.4
4.3
4.2
0
2
4
6
I
SOURCE
– mA
8
10
t
PD
V
OH
OUTPUT
V
OL
t
S
V
IH
LATCH
V
IL
TEMP = +25°C
TPC 7. Output High Voltage vs.
Source Current
TPC 8. Total Supply Current vs.
Temperature
t
S
= SETUP TIME
t
H
= HOLD TIME
t
PD
= COMPARATOR RESPONSE TIME
Figure 4. Latch Timing
REV.
E
–5–
