Rev 2.0 ©2010 Advanced Linear Devices, Inc. 415 Tasman Drive, Sunnyvale, CA 94089-1706 Tel: (408) 747-1155 Fax: (408) 747-1286
www.aldinc.com
ULTRA LOW VOS EPAD® DUAL CMOS ANALOG VOLTAGE COMPARATOR
ALD2321A/ALD2321B/ALD2321
ADVANCED
LINEAR
DEVICES, INC.
PIN CONFIGURATION
APPLICATIONS
• Dual limit window comparator
• Power supply voltage monitor
• Photo-detector sensor circuit
• Relay or LED driver
• Oscillators
• Battery operated instruments
• Remote signal detection
GENERAL DESCRIPTION
The ALD2321A/ALD2321B/ALD2321 is a monolithic Precision Dual Volt-
age Comparator, each having integrated dual complementary output
drivers. It is constructed using advanced silicon gate CMOS technology.
Key features of the ALD2321A/ALD2321B/ALD2321 include very high
input impedance, very low offset voltage utilizing on-chip e-trim (EPAD®
electronic-trimming) technology, flexible multiple output configurations and
fast response time with small overdrive voltage. It is designed for ultra low
level signal detection from high impedance sources. For many applications
the ALD2321A/ALD2321B/ALD2321 can eliminate an input amplification
stage, a precision input bias stage, a signal level shift stage and an output
buffer stage, and do the entire job from low level input signal detection to high
output driver -- all on a single chip.
The input voltage includes ground, making this voltage comparator ideal for
single supply (+5V) or dual supply (± 5V) powered systems. For dual supply
applications, GND pin is connected to the most negative supply instead of
Ground (0.0V). The negative supply voltage can be at any value between
0.0V and -5V. Each voltage comparator is individually trimmed at the factory
for minimum offset voltage at ground voltage potential, making the ALD2321A/
ALD2321B/ALD2321 at its best offset voltage and ready to compare very
low signal level voltages at or near ground potential. Typically a signal less
than 1mV can be resolved and detected reliably without requiring amplifica-
tion. Sensor or detector signals with signal power as low as 0.004pW (4 x
10-15 Watt) can be readily detected.
Each voltage comparator has two complementary output pins, one for
Source Output (OUTH) and the other for Sink Output (OUT). This dual
complementary output allows maximum circuit design flexibility. The out-
puts can be used as Single-Ended Driver, Multiple WIRED-OR Outputs,
Push-Pull Outputs or Complementary Outputs. The Sink Output can be
used as an open drain output, which has current sink capability of up to
50mA. It can also be connected to an external voltage higher or lower than
V+, which provide level shift of the output swing levels from other than V+
to GND. The Source Output can source up to 2mA and can be used to drive
the base terminal of an external NPN bipolar device or the gate of a N-
channel MOSFET device. Alternatively, the two outputs, Source Output and
FEATURES
• Ultra low signal power of 4fW detectable
• Ultra low offset voltage of max. 0.2mV
• Ultra low input bias currents of typ. 0.01pA
• Low supply current of 110µA typical
• Virtually eliminates source impedance effects
• Low operating supply voltage of 4V to 10V
• Single (+5V) and dual supply (±5V) operation
• High speed for both small and large level
signals 300ns typical for TTL inputs
• CMOS, NMOS and TTL compatible
• Each comparator has separate push and
pull outputs
• High output sink current - typically 50mA
• Low supply current spikes
• Fanout of 30 TTL loads
V+
1
2
314
15
16
413
512
N/C*
6
7
8
10
11
OUT1H
-IN1
OUT1
VE11
N/C*
VE12
9
VE22
VE21
OUT2H
OUT2
-IN2
+IN2
+IN1
GND
Operating Temperature Range *
0°C to +70°C0°C to +70°C -55°C to +125°C
16-Pin 16-Pin 16-Pin
Small Outline Plastic Dip CERDIP
Package (SOIC) Package Package
ALD2321ASCL ALD2321APCL ALD2321ADC
ALD2321BSCL ALD2321BPCL ALD2321BDC
ALD2321SCL ALD2321PCL ALD2321DC
ORDERING INFORMATION (“L” suffix for lead free version)
* Contact factory for leaded (non-RoHS) or high temperature versions.
SCL, PCL, DC PACKAGES
*N/C pins are connected internally.
Do not connect externally.
ALD2321A/ALD2321B/ALD2321 Advanced Linear Devices 2 of 11
Sink Output, can be connected together to form a push-pull output
which has the combined output capabilities of both channels.
In the dual complementary output mode, each comparator can be
used to drive separate loads. Due to the complementary nature of
the two outputs, only one output is active at any a given time, except
for a limited crossover time. When OUT (sink output) is active ON,
the OUT pin is sinking current and the OUTH pin is OFF and in high
impedance mode. Conversely, if OUTH pin is ON and sourcing
current, OUT pin is OFF. To configure push-pull output, simply
connect OUT (sink output) pin to OUTH pin.
Since each voltage comparator has its own complementary out-
puts, each comparator can be configured to have a different output
type. For example, one comparator output can be connected as
Open Drain output while the other comparator can be wired as
push-pull output. If used to drive capacitive loads, the output DC
current levels are at a very low level, at essentially leakage current
levels, which can be a power saving feature.
The ALD2321A/ALD2321B/ALD2321 can detect and resolve very
low voltage levels at high speed, with little or no overdrive voltage.
Compared with other voltage comparator devices that require 100
mV overdrive voltages, or multiple stage circuits that include input
preamp, etc., the ALD2321A/ALD2321B/ALD2321 can perform all
input to output functions in one device with minimal delay time and
with as low as a 1mV signal.
The ALD2321A/ALD2321B/ALD2321 is supplied with 4 external e-
trim pins, VE11, VE12, VE21, and VE22. These pins are used for
trimming of the voltage comparator offset voltages at the factory,
and normally should be left open unconnected. However, in some
cases these pins can be used as positive/negative feedback pins,
since these pins have a positive/negative factor on the offset
voltage. For example, see TYPICAL APPLICATIONS section
titled "Voltage Comparator With Output Feedback to Provide
Hysteresis."
GENERAL DESCRIPTION (cont'd)
In a printed circuit board layout, it is suggested that
these pins, along with no connect (N/C) pins 8 and 9,
be surrounded with ground traces to prevent any
possible crosstalk and noise coupling from other signal
sources.
Although not required for most applications, if neces-
sary, small valued capacitors of approximately 1000pF
can be mounted at these pins to ground to further
reduce noise. For information on customized trimming
under different biasing and power supply conditions,
please contact factory.
1 OUT1 COMPARATOR 1 SINK OUTPUT OUTPUT
2 OUT1H COMPARATOR 1 SOURCE OUTPUT OUTPUT
3 -IN1 COMPARATOR 1 INVERTING INPUT INPUT
4 +IN1 COMPARATOR 1 NON-INVERTING INPUT INPUT
5 GND GROUND / V- SUPPLY -
6VE
11 - VOS E-Trim COMPARATOR 1 INPUT
7VE
12 + VOS E-Trim COMPARATOR 1 INPUT
8 N/C No Connect/Do Not connect externally -
9 N/C No Connect/Do Not connect externally -
10 VE22 +VOS E-Trim COMPARATOR 2 INPUT
11 VE21 - VOS E-Trim COMPARATOR 2 INPUT
12 +IN2 COMPARATOR 2 NON-INVERTING INPUT INPUT
13 -IN2 COMPARATOR 2 INVERTING INPUT INPUT
14 OUT2H COMPARATOR 2 SOURCE OUTPUT OUTPUT
15 OUT2 COMPARATOR 2 SINK OUTPUT OUTPUT
16 V+ V+ SUPPLY -
ALD2321 PIN IDENTIFICATION
PIN # SYMBOL FUNCTION SIGNAL PROPAGATION
BLOCK DIAGRAM
(1) OUT
1
NONINVERTING INPUT
+IN
1
(4)
INVERTING INPUT 
-IN
1
(3)
(16)
V
+
(2) OUT
1H
VE
11
GND(6) (7) VE
12
(5)
(15) OUT
2
VE
21
INVERTING INPUT
-IN
2
(13)
(14) OUT
2H
VE
22
(11)
(10)
N/C
(8) (9)
N/C
NONINVERTING INPUT
+IN
2
(12)
-
+
-
+
ALD2321A/ALD2321B/ALD2321 Advanced Linear Devices 3 of 11
Supply VS ±2 ±5 ±2 ±5 ±2 ±5 V Dual Supply
Voltage V+ 4 10 4 10 4 10 V Single Supply
Supply Current IS 110 180 110 180 110 180 µA No Load
Current Two Comparators
Voltage Gain AVD 50 150 50 150 50 150 V/mV RLOAD ≥ 15K
Input Offset Voltage VOS 0.05 0.2 0.2 0.5 0.5 1.0 mV RLOAD ≥ 1.5KΩ
Input Offset Current1IOS 0.01 20 0.01 20 0.01 20 pA
Input Bias Current1 IB 0.01 20 0.01 20 0.01 20 pA
Common Mode Input VICR -0.3 V+ -1.5 -0.3 V+ -1.5 -0.3 V+ -1.5 V
Voltage Range2
Low Level Sink VOL 0.15 0.4 0.15 0.4 0.15 0.4 V ISINK = 12mA
Output Voltage VINPUT = 1V Differential
Low Level Sink IOL 24 50 24 50 24 50 mA VOL = 1.0 V
Output Current SINK OUTPUT ON
High Level Source VOH 3.5 4.5 3.5 4.5 3.5 4.5 V ISOURCE = -2mA
Output Voltage SOURCE OUTPUT ON
Source Output IHL 0.01 1 0.01 1 0.01 1 nA VOH = 0.0V
Leakage Current SOURCE OUTPUT OFF
Sink Output IL 0.01 20 0.01 20 0.01 20 nA VOUT = 5.0 V
Leakage Current SINK OUTPUT OFF
Response Time2tRP 1.1 1.1 1.1 µs RL = 5.1KΩ, CL = 15pF
5mV Input Step/
0mV Overdrive
tRP 2.4 2.4 2.4 µs RL = 5.1KΩ ,CL =15pF
1mVInput Step/
0mV Overdrive
Common Mode CMRR 80 80 80 dB VINPUT = 0V to 2.5V
Rejection Ratio
Power Supply PSRR 75 75 75 dB V+ = 4V to 5V
Rejection Ratio
Change of Vos / VExx ∆VOS 5 5 5 mV/V VE pins No Load
∆VE
OPERATING ELECTRICAL CHARACTERISTICS
TA = 25°C V+ = +5V unless otherwise specified
2321A 2321B 2321
Parameter Symbol Min Typ Max Min Typ Max Min Typ Max Unit Test Conditions
Notes: 1 Consists of junction leakage currents
2 Sample test parameter
ABSOLUTE MAXIMUM RATINGS
Supply voltage, V+ +10.6V
Differential input voltage range -0.3V to V+ +0.3V
Power dissipation 600 mW
Operating temperature range PCL, SCL packages 0°C to +70°C
DC package -55°C to +125°C
Storage temperature range -65°C to +150°C
Lead temperature, 10 seconds +260°C
ALD2321A/ALD2321B/ALD2321 Advanced Linear Devices 4 of 11
TYPICAL PERFORMANCE CHARACTERISTICS
SUPPLY CURRENT vs.TEMPERATURE
SUPPLY CURRENT (µA)
AMBIENT TEMPERATURE (°C)
-55 -25 025 50 12510075
160
140
120
100
60
80
180
200
V+ = +5V
No Load
Two Comparators
SUPPLY CURRENT vs. SUPPLY VOLTAGE
012
200
SUPPLY VOLTAGE (V)
SUPPLY CURRENT (µA)
0
108624
20
40
60
80
100
120
140
160
180 No Load
Two Comparators
TA = 25
0
C
TA = 125
0
C
TA = -55
0
C
-55 -25 0 25 50 75 100 125
0
1
10
100
1000
V
+
= +5V
INPUT BIAS CURRENT vs. TEMPERATURE
AMBIENT TEMPERATURE (
0
C)
INPUT BIAS CURRENT (pA)
LOW LEVEL OUTPUT VOLTAGE 
vs. TEMPERATURE
0.5
0.4
0.3
0.2
0.1
0.0
LOW LEVEL OUTPUT VOLTAGE (V)
AMBIENT TEMPERATURE (°C)
-55 -25 025 50 125
100
75
V
+
= +3.5V
V
+
= +5V
V
+
= +10V
I
SINK = 12mA
V
INPUT =
1V 
Differential
SATURATION VOLTAGE vs. SINK CURRENT
OUTPUT SINK CURRENT (mA)
015 30 45 60 75
OUTPUT SATURATION VOLTAGE (V)
3.0
2.0
1.0
0.0
2.5
1.5
0.5
V+ = +5V TA = 125
0
C
TA = -55
0
C
TA = 85
0
C
TA = 25
0
C
TA = -25
0
C
HIGH LEVEL OUTPUT VOLTAGE vs. HIGH
LEVEL OUTPUT LEAKAGE CURRENT
34567891011
0.0
0.1
1.0
10.0
100.0 V
OH
= V
+
HIGH LEVEL OUTPUT CURRENT (nA)
HIGH LEVEL OUTPUT VOLTAGE (V)
T
A
= 125
0
C
T
A
= 85
0
C
T
A
= 25
0
C
ALD2321A/ALD2321B/ALD2321 Advanced Linear Devices 5 of 11
COMMON MODE REJECTION RATIO
vs. TEMPERATURE
COMMON MODE REJECTION MODE 
(dB)
-55 -25 025 50 12510075
85.0
80.0
75.0
70.0
90.0
65.0
60.0
AMBIENT TEMPERATURE (°C)
V
+
= +5V
R
L
= 5.1KΩ
POWER SUPPLY REJECTION RATIO 
vs.TEMPERATURE
AMBIENT TEMPERATURE (
0
C)
-55 -25 0 25 50 100 12575
90.0
85.0
70.0
POWER SUPPLY REJECTION RATIO 
(dB)
80.0
75.0
65.0
60.0
V
+
= +5V
R
L
= 5.1KΩ
HIGH LEVEL OUTPUT VOLTAGE vs.
TEMPERATURE
8.0
6.0
4.0
0.0
HIGH LEVEL OUTPUT VOTAGE (V)
AMBIENT TEMPERATURE (°C)
-55 -25 0 25 50 125
10075
2.0
10.0
V
+
= +10V
V
+
= +5V
V
+
= +4V
IOH = -2mA
INPUT OFFSET VOLTAGE vs. TEMPERATURE
0.4
0.0
-0.4
0.8
-0.8
-1.2
1.2
-2.0
INPUT OFFSET VOLTAGE (mV)
-55 -25 0 25 50 12510075
AMBIENT TEMPERATURE (°C)
-1.6
2.0
1.6 R
L
= 5.1KΩ
V
+
= +5V
V
+
= +2.5V
RESPONSE TIME FOR VARIOUS INPUT 
 OVERDRIVES
OUTPUT VOLTAGE
(V)
-1.0
6.0
2.0
0.0
1.0
3.0
4.0
5.0
0.0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0
TIME (µS)
T
A
= 25
0
C
V
+
= +5V
1mV
2mV
5mV
10mV
20mV
50mV
R
L
= 5.1KΩ
C
L
= 15pF
Input Step
0.0 0.3 0.6 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0
-1.0
0.0
1.0
2.0
3.0
4.0
5.0
6.0
RESPONSE TIME FOR VARIOUS INPUT 
 OVERDRIVES
OUTPUT VOLTAGE
(V)
TIME (µS)
50mV
20mV
10mV
5mV 2mV 1mV
V+ = +5V
RL = 5.1KΩInput StepCL = 15pF
TA = 250C
TYPICAL PERFORMANCE CHARACTERISTICS (cont'd)
ALD2321A/ALD2321B/ALD2321 Advanced Linear Devices 6 of 11
VOLTAGE COMPARATOR
WITH +/-5V SUPPLY AND +5V RELAY DRIVE
PRECISION SINGLE SUPPLY VOLTAGE
COMPARATOR WITH DIRECT RELAY DRIVER

6810 12
4
2
SUPPLY VOLTAGE (V)
OUTPUT HIGH VOLTAGE
vs. SUPPLY VOLTAGE
OUTPUT HIGH VOLTAGE FROM V
+
(V)
T
A
= 25°C
I
OH
= -2mA
V+ -0.6
V+ -0.1
V+ -0.2
V+ -0.3
V+ -0.4
V+ -0.5
V+
6810 12
4
2SUPPLY VOLTAGE (V)
OUTPUT LOW VOLTAGE
vs. SUPPLY VOLTAGE
OUTPUT LOW VOLTAGE (V)
T
A
= 25°C
I
OL
= 12mA
0.0
0.2
0.4
0.5
0.6
0.1
0.3
TRANSFER FUNCTION
DIFFERENTIAL INPUT VOLTAGE (mV)
+6.0
-6.0
0.0
OUTPUT VOLTAGE (V)
+2.5
0.0
-2.5
TA = 25°C
VS = ±6V
COMMON - MODE VOLTAGE REFERRED 
TO SUPPLY VOLTAGE
TEMPERATURE (°C)
0.5
V+
-0.5
-1.0
0.5
V-
-0.5
COMMON - MODE VOLTAGE LIMITS (V)
-55 -25 0 25 50 12510075
≈≈
VS = ± 2.5 V
TYPICAL APPLICATIONS
+5
5V
RELAY
+
-
+5
V
IN
V
R
+
-
5V
RELAY
-5
+5
V
IN+
1K
V
IN-
TYPICAL PERFORMANCE CHARACTERISTICS (cont'd)
ALD2321A/ALD2321B/ALD2321 Advanced Linear Devices 7 of 11
VOLTAGE COMPARATOR WITH OUTPUT LEVEL
SHIFT AND HIGH CURRENT LOAD DRIVER
VOLTAGE COMPARATOR WITH
COMPLEMENTARY OUTPUT DRIVERS
VOLTAGE COMPARATOR WITH +/-5V
SUPPLY AND OUTPUT LEVEL SHIFT
VOLTAGE COMPARATOR WITH OUTPUT
FEEDBACK TO PROVIDE HYSTERSIS
VOLTAGE COMPARATOR WITH
COMPLEMENTARY OUTPUTS
+
-
+5V
V
A
= 0V to +10V
+10V
0
V
OUT
V
IN+
V
IN-
V
OUT
VOLTAGE COMPARATOR WITH SINGLE
SUPPLY AND OUTPUT LEVEL SHIFT
V
OUT
V
R
V
IN
2.2M
OUT
H
V
E22
+5V
+5V
R
Load
OUT
+
- 15K
-5V
+5V
VOUT
15K
100K
100K
0.1µF
0.1µF
+5V
0
VOUT
+5V
V
IN+
V
IN-
+5V
OUT
H
+
-
+5V R
Load1
=200Ω
-5V
V
A
= 1V to +30V
R
Load2
=1K
2N2222
15K
+
-
-5V
+5V
R
2
=50 200Ω
+5V
R
1
= 15K
R
Load
V
OUT
V
IN+
V
IN-
0.066V
-4V
V
OUT
-
-
+
+
Q
Q
V
IN
V
REF
V+
1/2 ALD2321
1/2 ALD2321
TYPICAL APPLICATIONS (cont'd)
ALD2321A/ALD2321B/ALD2321 Advanced Linear Devices 8 of 11
PINS OUT1, OUT1H, OUT2, OUT2H,
INTERNAL CIRCUIT CONFIGURATIONS
RESPONSE TIME MEASUREMENT CIRCUIT
E-TRIM CIRCUIT
+OUT
OUTH
Input 
Offset 
Trim
Circuit
Level
Shift/
Scaling
VE1x*
Input 
Offset 
Trim
Circuit
Level
Shift/
Scaling
VE2x*
+IN
-IN -
Response time is defined as the internal between the
application of an input step function and the instant
when the output reaches 50% of its maximum value
as measured by the following test circuit:
V+
V
LIMIT2
PHOTO-
DETECTOR
LIGHT
-
-
+
+
LED
BUZZER
V
LIMIT 1
V
External
1/2 ALD2321
1/2 ALD2321
LED turns on as photo-detector
voltage reaches VLIMIT1.
Both LED and horn turns on as photo-
detector voltage reachesVLIMIT2.
VEXTERNAL= +12V, V+ = +5V
DUAL LIMIT PHOTO DETECTOR MONTOR
DUAL LIMIT WINDOW COMPARTOR
+
+
-
-
1/2 ALD2321
OUTPUT HIGH FOR V
IN
<V
REF(HIGH)
R
LOAD
= 1.5KΩ
AND V
IN
> V
REF(LOW)
V
OUT
V+
V
REF(HIGH)
1/2 ALD2321
V
REF(LOW)
R
LOAD
V
IN
* These pins should be isolated by surrounding them with ground trace in user's applications.
OUT
1
V+
OUT
1H
OUT
1
OUT
2
V+
OUT
2H
OUT
2
+
-5.1KΩ
OUT
+5V
10X INPUT STEP
1KΩ
9KΩ
V
IN
TYPICAL APPLICATIONS (cont'd)
ALD2321A/ALD2321B/ALD2321 Advanced Linear Devices 9 of 11
16 Pin Plastic SOIC Package
E
D
e
A
A
1
b
S (45°)
L
C
H
S (45°)
ø
Millimeters Inches
Min Max Min MaxDim 1.75
0.25
0.45
0.25
10.00
4.05
6.30
0.937
8°
0.50
0.053
0.004
0.014
0.007
0.385
0.140
0.224
0.024
0°
0.010
0.069
0.010
0.018
0.010
0.394
0.160
0.248
0.037
8°
0.020
1.27 BSC 0.050 BSC
1.35
0.10
0.35
0.18
9.80
3.50
5.70
0.60
0°
0.25
A
A1
b
C
D-16
E
e
H
L
S
ø
SOIC-16 PACKAGE DRAWING
ALD2321A/ALD2321B/ALD2321 Advanced Linear Devices 10 of 11
16 Pin Plastic DIP Package
Millimeters Inches
Min Max Min MaxDim
A
A1
A2
b
b1
c
D-16
E
E1
e
e1
L
S-16
ø
3.81
0.38
1.27
0.89
0.38
0.20
18.93
5.59
7.62
2.29
7.37
2.79
0.38
0°
5.08
1.27
2.03
1.65
0.51
0.30
21.33
7.11
8.26
2.79
7.87
3.81
1.52
15°
0.105
0.015
0.050
0.035
0.015
0.008
0.745
0.220
0.300
0.090
0.290
0.110
0.015
0°
0.200
0.050
0.080
0.065
0.020
0.012
0.840
0.280
0.325
0.110
0.310
0.150
0.060
15°
PDIP-16 PACKAGE DRAWING
b1
D
S
be
A2
A1
A
L
EE1
ce1ø
ALD2321A/ALD2321B/ALD2321 Advanced Linear Devices 11 of 11
EE
1
A
A
1
b
b
1
C
D-16
E
E
1
e
e
1
L
L
1
L
2
S
Ø
3.55
1.27
0.97
0.36
0.20
--
5.59
7.73
3.81
3.18
0.38
--
0°
5.08
2.16
1.65
0.58
0.38
21.34
7.87
8.26
5.08
--
1.78
2.49
15°
Millimeters Inches
Min Max Min MaxDim 0.140
0.050
0.038
0.014
0.008
--
0.220
0.290
0.150
0.125
0.015
--
0°
0.200
0.085
0.065
0.023
0.015
0.840
0.310
0.325
0.200
--
0.070
0.098
15°
2.54 BSC
7.62 BSC
0.100 BSC
0.300 BSC
D
s
b
1
e
b
L
A
L
2
A
1
L
1
C
e
1
ø
16 Pin CERDIP Package
CERDIP-16 PACKAGE DRAWING