GENERAL DESCRIPTION (cont'd)
The Source Output can source up to 2 mA 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 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 OUT
H
pin is OFF and in high impedance mode. Con-
versely, if OUT
H
pin is ON and sourcing current, OUT pin is
OFF. To configure push-pull output, simply connect OUT (sink
output) pin to OUT
H
pin.
Since each voltage comparator has its own complementary
outputs, 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
ALD2321 PIN IDENTIFICATION
PIN #
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
SYMBOL
OUT1
OUT1H
-IN1
+IN1
GND
VE11
VE12
N/C
N/C
VE22
VE21
+IN2
-IN2
OUT2H
OUT2
V+
FUNCTION
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 TYPI-
CAL APPLICATIONS section titled "Voltage Comparator
With Output Feedback to Provide Hysteresis."
In 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 necessary,
small valued capacitors of approximately 1000 pF 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.
BLOCK DIAGRAM
(16) V
+
INVERTING INPUT
-IN
1
(3)
NONINVERTING INPUT
+IN
1
(4)
-
(2) OUT
1H
(1) OUT
1
+
(7) VE
12
(6) VE
11
(5) GND
INVERTING INPUT
-IN
2
(13)
NONINVERTING INPUT
+IN
2
(12)
-
+
(10) VE
22
(11) VE
21
(14) OUT
2H
(15) OUT
2
(8)
N/C
(9)
N/C
SIGNAL PROPAGATION
OUTPUT
OUTPUT
INPUT
INPUT
-
INPUT
INPUT
-
-
INPUT
INPUT
INPUT
INPUT
OUTPUT
OUTPUT
-
2
COMPARATOR 1 SINK OUTPUT
COMPARATOR 1 SOURCE OUTPUT
COMPARATOR 1 INVERTING INPUT
COMPARATOR 1 NON-INVERTING INPUT
GROUND / V- SUPPLY
- VOS E-Trim COMPARATOR 1
+ VOS E-Trim COMPARATOR 1
No Connect/Do Not connect externally
No Connect/Do Not connect externally
+VOS E-Trim COMPARATOR 2
- VOS E-Trim COMPARATOR 2
COMPARATOR 2 NON-INVERTING INPUT
COMPARATOR 2 INVERTING INPUT
COMPARATOR 2 SOURCE OUTPUT
COMPARATOR 2 SINK OUTPUT
V+ SUPPLY
Advanced Linear Devices
ALD2321A/ALD2321B
ALD2321
ALD [ ADVANCED LINEAR DEVICES ]
