M74HCT244B1 - Octal 3-State Bus Buffer, HCT, DIP-20 | STMicroelectronics
N.º de pieza: M74HCT244B1 ✓ Activo| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $0.95 | $0,95 |
| 10 | $0.85 | $8,50 |
| 100 | $0.72 | $72,00 |
| 500 | $0.58 | $290,00 |
| 1.000 | $0.46 | $460,00 |
M74HCT244B1 Descripción general
An HCT logic interface — 74HCT — is a high-speed CMOS logic family with TTL-compatible input voltage thresholds (VIH = 2.0 V min, VIL = 0.8 V max) that allows direct interfacing with bipolar TTL outputs while preserving the low power consumption of CMOS. Within the broader taxonomy, the M74HCT244B1 belongs to the buffer/driver category of standard logic ICs (74-series logic > buffer/driver ICs > interface ICs > integrated circuits). This HCT sub-family operates from a single 4.5 V to 5.5 V supply, making it the standard logic choice for 5 V digital systems that must bridge CMOS controllers with legacy TTL peripherals.
Key features include a typical propagation delay of 12 ns at VdM8 = 5 V, low quiescent supply current (ICC of 4 µA max per channel), 6 mA standard output drive, and ±20 mA balanced output drive capability at 5 V. All inputs include protection circuits against static discharge and transient excess voltage, and the device is specified over the commercial 0 °C to +70 °C operating temperature range (B1 suffix), with a -40 °C to +85 °C industrial variant (B1R suffix) also available from STMicroelectronics. The C2MOS silicon-gate process yields low power dissipation (ICC quiescent of 80 µA max for the whole IC) while delivering CMOS-equivalent speed.
Typical applications include memory and address bus buffering in microprocessor systems, peripheral interface drivers for 5 V logic, LED display driving, and general-purpose bus isolation in industrial control and instrumentation. Two active-low output enables let designers independently disable the upper and lower nibbles, which is convenient for 8-bit bus demultiplexing or for tri-state bus sharing among multiple masters.
When designing with this part, place a 0.1 µF decoupling capacitor as close as possible to VCC pin 20 to suppress switching transients, and ensure both 1OE and 2OE are tied high through pull-ups if always-enabled operation is desired. The DIP-20 footprint remains popular for through-hole prototyping and legacy board retrofits, while the surface-mount M74HCT244M1R (SO-20) variant serves modern SMT designs.
This page synthesizes STMicroelectronics datasheet parameters, distributor pricing, drop-in 74HCT244 equivalents from ST/TI/onsemi/NXP, and practical design notes not bundled in a single distributor listing.
Alternativas directas para M74HCT244B1 — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
Herramienta de comparación rápida — seleccione piezas alternativas para compararlas lado a lado:
M74HCT244B1R
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
M74HCT244M1R
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SN74HCT244N
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
CD74HCT244E
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
MC74HCT244ANG
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
74HCT244N
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
M74HCT244B1 Valores máximos y características eléctricas
| Logic Family | 74HCT |
| Función | Octal bus buffer / line driver |
| Number of Channels | 8 (organized as 2 x 4-bit groups) |
| Number of Elements | 2 |
| Bits per Element | 4 |
| Polarity | Non-inverting |
| Tipo de salida | 3-State |
| Output Enable | 1OE, 2OE (active low) |
| Supply Voltage (VCC) | 4.5 V to 5.5 V |
| Input Voltage Threshold VIH | 2.0 V min |
| Input Voltage Threshold VIL | 0.8 V max |
| Temperatura de funcionamiento | 0 °C to +70 °C (commercial B1 suffix) |
| Encapsulado | 20-pin DIP (B1, through-hole) |
| Technology | Silicon-gate C2MOS |
| Input Protection | Static discharge and transient excess voltage protection |
| Tipo de montaje | Through-Hole |
Configuración de pines de M74HCT244B1
| Pin 1 | 1OE — Output enable, group 1 (active LOW) |
| Pin 2 | 1A0 — Data input A0, group 1 |
| Pin 3 | 1A1 — Data input A1, group 1 |
| Pin 4 | 1A2 — Data input A2, group 1 |
| Pin 5 | 1A3 — Data input A3, group 1 |
| Pin 6 | 1Y0 — Data output Y0, group 1 (3-state, non-inverting) |
| Pin 7 | 1Y1 — Data output Y1, group 1 (3-state, non-inverting) |
| Pin 8 | 1Y2 — Data output Y2, group 1 (3-state, non-inverting) |
| Pin 9 | 1Y3 — Data output Y3, group 1 (3-state, non-inverting) |
| Pin 10 | GND — Ground |
| Pin 11 | 2Y0 — Data output Y0, group 2 (3-state, non-inverting) |
| Pin 12 | 2Y1 — Data output Y1, group 2 (3-state, non-inverting) |
| Pin 13 | 2Y2 — Data output Y2, group 2 (3-state, non-inverting) |
| Pin 14 | 2Y3 — Data output Y3, group 2 (3-state, non-inverting) |
| Pin 15 | 2A0 — Data input A0, group 2 |
| Pin 16 | 2A1 — Data input A1, group 2 |
| Pin 17 | 2A2 — Data input A2, group 2 |
| Pin 18 | 2A3 — Data input A3, group 2 |
| Pin 19 | 2OE — Output enable, group 2 (active LOW) |
| Pin 20 | VCC — Positive supply voltage (4.5 V to 5.5 V) |
Aplicaciones típicas
M74HCT244B1 es adecuado para 7 aplicacións: Microprocessor Address/Data Bus Buffer, 5V Logic-Level Translation Bridge, LED Display Driving, Industrial Control Signal Conditioning, Memory Address Bus Driver, Peripheral Interface Driver, Test and Measurement Backplane.
Microprocessor Address/Data Bus Buffer
The M74HCT244B1 sits between a 5 V microcontroller address or data bus and downstream peripherals such as memory or I/O expanders, isolating capacitive load and preventing bus contention. Its 6 mA standard output drive and TTL-compatible inputs (VIH = 2.0 V, VIL = 0.8 V) make it ideal for bridging CMOS microcontrollers (e.g., 8051, PIC, AVR) with multiple 5 V peripherals on a shared bus. The two independent active-low output enables (1OE, 2OE) allow independent control of upper and lower nibbles, simplifying 8-bit to dual 4-bit bus splitting. Octal bus buffers extend fan-out without degrading signal integrity in long-trace or heavily-loaded designs.
Recomendado
5V Logic-Level Translation Bridge
The M74HCT244B1 bridges 5 V TTL output signals to 5 V CMOS inputs with full TTL-threshold compatibility. Inputs accept any signal with VIH >= 2.0 V, so bipolar TTL drivers, optocouplers, and 5 V CMOS controllers can all feed the buffer without external level shifting. Output 3-state capability prevents back-driving shared lines during bus arbitration, while low quiescent current keeps continuous current draw minimal when both OE pins are HIGH. This makes the part a clean choice for legacy-to-modern 5 V system integration where older peripherals must coexist with newer CMOS-only controllers.
Recomendado
LED Display Driving
The M74HCT244B1 drives multiplexed LED arrays, 7-segment displays, and indicator panels by sourcing/sinking current per channel through standard logic output stages. With ±20 mA output drive capability at 5 V, the device can directly drive low-current LED segments without additional transistor drivers. Independent output enables (1OE, 2OE) support time-multiplexed scanning of dual 4-digit 7-segment displays with simple GPIO control. Because HCT inputs accept TTL-level signals from older controllers, designers can replace discrete transistor driver boards with a single 20-pin IC, reducing PCB area and BOM count in legacy HMI designs.
Recomendado
Industrial Control Signal Conditioning
The M74HCT244B1 isolates and re-drives 5 V control signals in PLCs, motor drivers, and industrial automation backplanes. Inputs are protected against static discharge and transient excess voltage, which suits the harsh electrical environments of factory floors. The 3-state outputs prevent crosstalk when multiple controllers share a parallel backplane, while low ICC quiescent current enables 24/7 always-on operation without thermal stress. With its industrial temperature range option (M74HCT244B1R, -40 to +85 °C), the buffer tolerates the wide thermal swings of unheated control cabinets, making it a staple in legacy factory-floor designs.
Recomendado
Memory Address Bus Driver
The M74HCT244B1 buffers address lines between a CPU and multiple memory banks (SRAM, EPROM, EEPROM), maintaining signal integrity when the address bus fans out to several high-pin-count memories. Two active-low output enables (1OE, 2OE) allow bank-select isolation: pulling 1OE HIGH puts the upper four address lines into high-Z while the lower four remain active, or vice versa. This makes the buffer suitable for bank-switched memory expansion schemes. With TTL-compatible inputs, the part drives any 5 V memory interface cleanly without timing skew across long PCB traces, supporting deterministic read/write cycles in microcontroller-based designs.
Recomendado
Peripheral Interface Driver
The M74HCT244B1 acts as a robust 5 V peripheral interface driver, isolating a host microcontroller from parallel-port peripherals such as printers, industrial sensors, or LCD modules. Its non-inverting data path preserves signal polarity from host to peripheral, and 3-state outputs allow safe bus sharing with handshake signals on the return path. TTL-compatible inputs accept logic levels from any 5 V peripheral, while standard CMOS output drive maintains signal rise/fall times across cables up to several meters in length. This combination makes the device a reliable choice for legacy parallel-port designs and instrumentation front ends.
Recomendado
Test and Measurement Backplane
The M74HCT244B1 drives backplane signal lines in test fixtures, logic analyzers, and bench instrumentation where multiple test points must be connected or isolated dynamically. Each of the eight channels can be independently routed to a DUT via separate OE control lines, allowing the same fixture to test several boards with different bus topologies. The low propagation delay through the buffer preserves timing margins in high-speed digital test sequences, and the HCT logic family avoids extra level-shift stages when interfacing with TTL-based test equipment. This simplifies fixture design and reduces the BOM count in production testers.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para M74HCT244B1 — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | M74HCT244B1R | SN74HCT244N | CD74HCT244E | MC74HCT244ANG | 74HCT244N |
|---|---|---|---|---|---|---|
| Package | PDIP-20 | PDIP-20 - same | PDIP-20 - same | PDIP-20 - same | PDIP-20 - same | PDIP-20 - same |
| Brand | STMicroelectronics | STMicroelectronics (same brand) | Texas Instruments | Texas Instruments | onsemi | NXP Semiconductors |
| Function | Octal 3-state non-inverting buffer | Octal 3-state non-inverting buffer | Octal 3-state non-inverting buffer | Octal 3-state non-inverting buffer | Octal 3-state non-inverting buffer | Octal 3-state non-inverting buffer |
| Supply Voltage (VCC) | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V | 4.5 V to 5.5 V |
| Logic Family | 74HCT (TTL-compatible inputs) | 74HCT | 74HCT | 74HCT | 74HCT | 74HCT |
| Number of Channels | 8 | 8 | 8 | 8 | 8 | 8 |
| Output Enable Polarity | Active LOW (1OE, 2OE) | Active LOW | Active LOW | Active LOW | Active LOW | Active LOW |
| Operating Temperature | 0 °C to +70 °C (commercial) | -40 °C to +85 °C (industrial) | -40 °C to +85 °C | -55 °C to +125 °C (military) | -55 °C to +125 °C | -40 °C to +125 °C |
| Approx. Unit Price (qty 1, USD) | 0.95 | 0.90 - 1.00 | 0.70 - 0.90 | 0.85 - 1.05 | 0.55 - 0.75 | 0.40 - 0.60 |
Diferenciadores clave
- STMicroelectronics original silicon-gate C2MOS design with TTL-compatible inputs (frente a SN74HCT244N)
- Two independent active-low output enables for nibble-level bus control (frente a 74HCT245)
- Lower quiescent current than bipolar 74LS244 (frente a 74LS244)
- PDIP-20 package ideal for breadboard and through-hole prototype use (frente a M74HCT244M1R)
Notas de diseño
Decouple VCC (pin 20) with a 0.1 µF ceramic capacitor placed as close to the IC as PCB layout allows, ideally within 5 mm of the package pin. The C2MOS silicon-gate process draws very low quiescent current (sub-mA typical), but fast edge rates on the 3-state outputs inject switching transients into VCC that a single decoupling cap absorbs cleanly. For multi-channel simultaneous switching at 5 V, add a 1 µF to 10 µF bulk bypass in parallel to handle the worst-case transient load.
Keep input traces short and isolated from output traces of the same channel to minimize coupling that could cause oscillation in high-impedance states. Both 1OE and 2OE are active-low enables - if the buffer is meant to be always enabled, tie these pins directly to GND through a short trace, or drive them with a dedicated GPIO that defaults LOW at power-up. Floating OE pins can drift into the linear region and cause partial output conduction, raising supply current.
Do not exceed VCC = 5.5 V or drive inputs above 5.5 V without a series resistor or clamp. The HCT input thresholds assume a 5 V nominal supply; on a 3.3 V system, an HCT input may interpret a 3.3 V logic HIGH as marginal because VIH = 2.0 V is satisfied but noise margin shrinks. Use a true 74HC or 74LVC variant for 3.3 V designs, or insert a 74HCT244B1 only on a 5 V island. Never connect M74HCT244B1 outputs together when both OE pins are LOW or current contention will result.
The M74HCT244B1 output drive is rated at ±6 mA typical / ±20 mA maximum per channel, but simultaneously driving all eight channels at the maximum rating will stress the internal bond wires and lift junction temperature. For bus-loading analysis, assume a 50 pF load per channel and verify that propagation delay plus rise/fall time keeps timing margins intact in the target system. When the buffer fans out to long cables, place a series damping resistor (22-100 Ω) at each output to limit ringing on fast edges.
Información de cumplimiento
Compliance status not stated verbatim in the provided web snippets. STMicroelectronics' general 74-series logic ICs are typically RoHS compliant and lead-free in modern production, but verify the specific lot via manufacturer documentation before volume procurement.
