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

Description

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 it’s easy to drop into breadboards, PCBs or existing TTL designs. Because it’s 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=Min Iol=4mA 54, 74 0.25 0.4 V Vol Low-level output voltage Vil=Max Iol=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 μA 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.

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