7421 Dual 4-Input AND Gates 7V 2.2A IC PDIP-14

7421 Dual 4-Input
AND Gates
7V 2.2A IC PDIP-14

The 7421 (GD74LS21 / SN74LS21 family) contains two independent positive-AND gates, each with four inputs. Each gate produces a HIGH only when all four inputs on that gate are HIGH, letting designers combine multiple control or sensor signals into a single logic enable or decision line. The device is part of the 74LS (Low-power Schottky TTL) family and is pin-compatible with standard 14-pin DIP/SOIC packages, so its easy to drop into breadboards, PCBs or existing TTL designs.

Because its a TTL LS device, the GD74LS21 is optimized for direct interfacing with other TTL/CMOS logic while offering reasonable output drive for typical logic loads. Typical uses include gating multiple control signals (interrupt enables, chip-select gating), building simple combinational logic without a microcontroller, glue logic between subsystems, or extending bus control where multiple conditions must be true before an action occurs. The part is widely available in PDIP, SOIC and other package options, and is characterized for standard commercial temperature ranges.

Features:

Two independent 4-input positive AND gates.

TTL (Low-power Schottky, LS) logic family.

Inputs are pulled/biased to TTL levels and outputs are buffered.

Directly interfaces with other TTL and common CMOS logic.

Multiple package option (PDIP).

Simple single-supply 5V logic operation.

Specifications:

SYMBOL

PARAMETER

TEST CONDITIONS

MIN (Note 1)

TYP

MAX

UNIT

Vih

High-level input voltage

2

V

Vil

Low-level input voltage

54

0.7

V

Vil

Low-level input voltage

74

0.8

V

Vik

Input clamp voltage

Vcc=Min,Ii=18mA

-1.5

V

Voh

High-level output voltage

Vcc=Min,Ioh=Max,Vih=Min
Vcc
=
Min
,
I
Ooh
=
Max
,
Vih

=
Min

54

2.5

3.4

V

Voh

High-level output voltage

74

2.7

3.4

V

Vol

Low-level output voltage

Vcc=MinIol=4mA

54, 74

0.25

0.4

V

Vol

Low-level output voltage

Vil=MaxIol=8mA

74

0.35

0.5

V

Ii

Input current at maximum input voltage

Vcc=Max,Vi=7V

0.1

mA

Iih

High-level input current

Vcc=Max,Vi=2.7V

20

A

Iil

Low-level input current

Vcc=Max,Vi=0.4V

-0.4

mA

Ios

Short-circuit output current

Vcc=Max
Vcc

=
Max

-20

-100

mA

Icch

Supply current

Total with outputs high

Vcc=Max
Vcc

=
Max

1.2

2.4

mA

Iccl

Supply current

Total with outputs low

Vcc=Max
Vcc
=
Max

2.2

4.4

mA

Pinout:

Pin

Name

Description

1

A1

Gate 1 input A

2

B1

Gate 1 input B

3

NC

No connection

4

C1

Gate 1 input C

5

D1

Gate 1 input D

6

Y1

Gate 1 output

7

GND

Ground

8

Y2

Gate 2 output

9

A2

Gate 2 input A

10

B2

Gate 2 input B

11

NC

No connection

12

C2

Gate 2 input C

13

D2

Gate 2 input D

14

VCC

+5V supply

Applications:

Glue logic and combinational gating (chip-selects, enables).

Interrupt masking and multi-condition control.

Simple hardware decision logic (safety interlocks, sensor aggregation).

TTL/legacy system repair and prototyping.

Educational electronics and breadboard prototyping.

Packages:

1x 7421 Dual 4-Input AND Gates 7V 2.2A IC PDIP-14.

Documents:

7421 Datasheet.