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SN74LS20N

Dual 4-input NAND gate, LS TTL, 15ns, PDIP-14

6000

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جزء الشركة المصنعة ： جزء الشركة المصنعة

SN74LS20N

الحزمة ： الحزمة

PDIP-14 (19.3 x 6.35 x 4.57mm, 2.54mm pitch, through-hole)

العلامة التجارية ： العلامة التجارية

فئات المنتجات:：فئات المنتجات

الدوائر المتكاملة الدوائر المتكاملة, واجهة ICs

توصيات أخرى قد تكون مهتماً بها.

SII9396SCNUC-BAR

IS43TR16256BL-125KBLI

الوصف

نظرة عامة على المنتج

The SN74LS20N from Texas Instruments contains two independent 4-input positive NAND gates in a 14-pin PDIP package — essential for implementing wide AND/NAND logic functions with minimal chip count.

المواصفات الرئيسية

Number of Gates	2 (dual 4-input NAND)
عائلة المنطق	LS (Low-power Schottky)
جهد الإمداد	4.75V to 5.25V
تأخير الانتشار	15ns typical @ 5V
Output Drive (IOL/IOH)	8mA / -0.4mA
درجة حرارة التشغيل	0°C to +70°C
الحزمة	PDIP-14 (19.3 x 6.35mm)

الميزات

Dual 4-input NAND gates
LS TTL technology
15ns typical propagation delay
Industry-standard 7420 pinout

التطبيقات

4-input AND function (NAND + inverter)
Address decoding with 4 conditions
Multi-condition gating
General-purpose logic

مقدمة المنتج:SN74LS20N مقدمة المنتج

The SN74LS20N from Texas Instruments contains two independent 4-input NAND gates in a 14-pin PDIP package. Each gate performs Y = NOT(A AND B AND C AND D); the output is LOW only when ALL four inputs are HIGH. This 4-input NAND is valuable for address decoding and multi-condition gating where four signals must all be HIGH (or a combination of HIGH/LOW with inverters) to produce an active output. A 4-input AND function is obtained by adding an inverter after the NAND. Without the 7420, implementing a 4-input AND would require cascading two 2-input AND gates (7408) plus an extra gate — three gates versus one. DeMorgan’s theorem shows that a 4-input NAND is also equivalent to NOT-A OR NOT-B OR NOT-C OR NOT-D, making it useful for detecting when ANY input is LOW. The N suffix denotes the PDIP-14 through-hole package.

مبدأ العمل:SN74LS20N مبدأ العمل

Each 4-input NAND gate performs Y = (A · B · C · D)’ — the output is LOW only when all four inputs A, B, C, and D are simultaneously HIGH. If any input is LOW, the output is HIGH. Truth table for one gate: 16 possible input combinations, only one (1111) produces LOW output. The NAND is a universal gate: any Boolean function can be implemented using only NAND gates. For a 4-input AND: Y = (A·B·C·D)” = A·B·C·D — add an inverter (7404 or one input of a NAND gate with tied inputs) after the 4-input NAND. For address decoding: if a memory device must be selected when A15=1, A14=1, A13=1, and MREQ=0, connect A15,A14,A13,MREQ’ (inverted) to the four inputs; the NAND output goes LOW only when all conditions are met (active-LOW chip select). The 15ns propagation delay means the output responds within 15ns of any input change.

وصف الدبوس:SN74LS20N تعريف الدبوس ووظائفه

دبوس	الاسم	النوع	الوصف
1	1A	المدخلات	Gate 1 input A
2	1B	المدخلات	Gate 1 input B
3	نورث كارولاينا	—	No connect
4	1C	المدخلات	Gate 1 input C
5	1D	المدخلات	Gate 1 input D
6	1Y	المخرجات	Gate 1 output (NAND)
7	GND	الطاقة	أرضي
8	2Y	المخرجات	Gate 2 output (NAND)
9	2A	المدخلات	Gate 2 input A
10	2B	المدخلات	Gate 2 input B
11	نورث كارولاينا	—	No connect
12	2C	المدخلات	Gate 2 input C
13	2D	المدخلات	Gate 2 input D
14	VCC	الطاقة	Supply (5V)

SN74LS20N uses the PDIP-14 package with standard 74LS TTL pinout: VCC at Pin 14, GND at Pin 7. Each NAND gate has four inputs and one output — Gate 1: Pins 1-4 (inputs), Pin 6 (output); Gate 2: Pins 9-12 (inputs), Pin 8 (output). Pins 5 and 13 are not connected. The LS technology provides typical propagation delay of 15ns and power dissipation of 2mW per gate. For push-pull active pull-up outputs, use SN74HC20N or SN74HCT20N which maintain the same pinout. The 74ALS20 provides lower power at similar speed as an advanced alternative.

Application Scenarios:In which products and applications isSN74LS20N مستعمل

4-Input AND: 4 signals → 7420 NAND → 7404 inverter → active-HIGH when all 4 inputs are HIGH
Chip Select Decode: A15, A14, A13, MREQ’ → 7420 → active-LOW chip select; LOW only when all 4 are HIGH
Multi-Condition Enable: System OK = PowerGood AND NoFault AND NoOvertemp AND NoAlarm; 4 signals → NAND → inverter → active-HIGH system OK
5+ Input AND: Combine 7420 output with 5th input in 7400 NAND → inverter; 5-input AND

Alternative Models:What chips are recommended as replacements for SN74LS20N

الطراز	الشركة المصنعة	الفرق الرئيسي	الحزمة	Supply
74LS20N	TI/Nexperia	Original TTL version with 5V-only supply, typical propagation delay 10-15ns	DIP-14	5V TTL
74LS20D	TI/Nexperia	Surface-mount SOIC version of LS with identical logic function	SOIC-14	5V TTL
74HC20D	TI/Nexperia	CMOS version with wide 2-6V supply range, lower power consumption and higher noise immunity	SOIC-14	2-6V CMOS
74HC20N	TI/Nexperia	Through-hole DIP version of HC family for prototyping and repair	DIP-14	2-6V CMOS
74HCT20D	TI/Nexperia	CMOS with TTL-compatible input levels, ideal for mixing with LS devices at 5V	SOIC-14	4.5-5.5V TTL-in
74HCT20N	TI/Nexperia	Through-hole DIP version of HCT family for prototyping and repair	DIP-14	4.5-5.5V TTL-in
74AC20D	TI/Nexperia	Advanced CMOS with 2-6V supply and higher output drive current (24mA vs 6mA for HC)	SOIC-14	2-6V CMOS
74AC20N	TI/Nexperia	Through-hole DIP version of AC family for prototyping and repair	DIP-14	2-6V CMOS
74LVC20D	TI/Nexperia	Low-voltage CMOS for 1.65-3.6V modern logic with 24mA output drive and bus-hold inputs	SOIC-14	1.65-3.6V CMOS
74LVC20N	TI/Nexperia	Through-hole DIP version of LVC family for prototyping and repair	DIP-14	1.65-3.6V CMOS

The 7420 is a Dual 4-Input NAND Gate. Family variants span from the original LS TTL (5V only) to modern LVC/AUP (down to 0.8V). HC and HCT versions offer 2-6V CMOS operation with HCT providing TTL-compatible input thresholds for mixed 5V systems. CD4000-series equivalents offer the widest 3-18V supply range at the cost of lower switching speed. DIP packages (N suffix) are through-hole; SOIC (D suffix) and TSSOP are surface-mount.