ALD2321A/ALD2321B

Advanced Linear Devices

2

ALD2321

BLOCK DIAGRAM

PIN #

SYMBOL

FUNCTION

SIGNAL PROPAGATION

ALD2321 PIN IDENTIFICATION

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

-

6VE11

- VOS E-Trim COMPARATOR 1

INPUT

7VE12

+ 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

-

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

OFF. To configure push-pull output, simply connect OUT (sink

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

GENERAL DESCRIPTION (cont'd)

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.

NONINVERTING INPUT

INVERTING INPUT

GND

(6)

(5)

INVERTING INPUT

(11)

(10)

N/C

(8)

(9)

N/C

NONINVERTING INPUT

-

+

-

+