Texas Instruments SN74BCT2827CNS

Overview

SN74BCT2827CNS from Texas Instruments is a 10-bit BiCMOS non-inverting buffer/driver with dual 3-state enable inputs (OE1, OE2), designed for high-speed MOS DRAM address/data bus interfacing. It operates at 4.5–5.5 V, delivers 12 mA sink current per output, features 25-Ω on-chip output termination, and supports 0°C to 70°C industrial temperature range.

For engineers reviewing the SN74BCT2827CNS datasheet, SN74BCT2827CNS pinout, SN74BCT2827CNS application, or SN74BCT2827CNS equivalent, key selection criteria include its flow-through pinout for PCB layout optimization, power-up high-impedance state, 5.2 ns max tPLH propagation delay at 5 V/50 pF, and compatibility with legacy TTL-level control signals.

Technical Context

This device implements a dual-input AND-gated 3-state control logic: outputs enter high-impedance when either OE1 or OE2 is high, ensuring robust bus arbitration in shared-memory systems. Its BiCMOS architecture combines bipolar input stages for TTL-compatible thresholds (VIH = 2 V, VIL = 0.8 V) with CMOS-like low ICCZ quiescent current (3.8–6 mA).

Each output integrates an internal 25-Ω series resistor, eliminating external termination components while maintaining signal integrity on capacitive DRAM buses. The flow-through pinout-inputs on one side (pins 1–11, 13), outputs on the opposite (pins 14–24)-reduces trace crossovers and improves signal routing efficiency.

Key Specifications

Pinout & Package

SN74BCT2827CNS is packaged in a 24-pin plastic small-outline (SOIC) DW package (15.4 mm × 7.5 mm, 1.27 mm pitch), RoHS-compliant with CU NIPDAU finish and moisture sensitivity level (MSL) Level-1.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 10-bit bus driver applications.

Compared with SN74ACT244N and 74F244SC, the SN74BCT2827CNS uniquely combines 10-bit width, integrated 25-Ω termination, flow-through layout, and power-up high-Z - making it optimal for space-constrained, high-reliability DRAM bus designs requiring zero external components.

Availability

SN74BCT2827CNS is available at Aetrix Electronics and suitable for DRAM address buffering, parity bus interfacing, legacy system memory expansion, and industrial control backplane interface requiring stable component supply and long-term obsolescence management.

Supply support for SN74BCT2827CNS includes scheduled delivery planning, volume procurement assistance, BOM continuity management, traceable sourcing, and lifecycle availability coordination for OEM customers, industrial embedded developers, connected-device designers, and electronics production programs.

Manufacturer

Texas Instruments is a global semiconductor leader founded in 1930, specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The SN74BCT2827CNS belongs to TI's BCT (Bipolar-CMOS Transistor) logic family, engineered specifically for high-speed, low-power interfacing between TTL controllers and capacitive MOS memory loads.

FAQ

What is the function of the dual OE inputs on the SN74BCT2827CNS?

The SN74BCT2827CNS uses two active-low 3-state enable inputs (OE1 and OE2) wired as an AND gate: outputs enter high-impedance whenever either input is high. This allows flexible bus arbitration-e.g., OE1 can be tied to CPU write strobe and OE2 to memory select-ensuring clean isolation during idle or conflict conditions. The SN74BCT2827CNS maintains this behavior across its full 0°C to 70°C operating range.

Does the SN74BCT2827CNS require external termination resistors?

No. The SN74BCT2827CNS integrates 25-Ω series resistors on all ten outputs, explicitly designed to match typical PCB trace impedances and dampen reflections when driving MOS DRAM inputs. This eliminates the need for 20 discrete resistors in a 10-bit bus, reducing bill-of-materials cost and PCB real estate. The SN74BCT2827CNS achieves this without compromising propagation delay or output drive strength.

Is the SN74BCT2827CNS pin-compatible with older 74LS244 devices?

No-the SN74BCT2827CNS is a 10-bit device in a 24-pin SOIC (DW) package with flow-through pinout (A1–A10 on left, Y1–Y10 on right), whereas the 74LS244 is an 8-bit device in a 20-pin DIP/SOIC with interleaved I/O. While both serve bus-driving roles, the SN74BCT2827CNS offers higher channel count, integrated termination, and superior speed/power trade-offs-but requires PCB layout revision. The SN74BCT2827CNS is not a drop-in replacement for 74LS244.

What is the maximum capacitive load the SN74BCT2827CNS can reliably drive?

The SN74BCT2827CNS is characterized for CL = 50 pF in switching tests and explicitly designed to drive the capacitive input characteristics of MOS DRAMs-typically 10–30 pF per pin. With 12 mA sink capability and 25-Ω series resistance, it maintains signal integrity up to ~75 pF total load per output under worst-case timing conditions. Exceeding this may degrade tPLH/tPHL beyond the 5.2/7.2 ns max specs. The SN74BCT2827CNS datasheet confirms performance at 50 pF; derating is recommended above that value.

How does the SN74BCT2827CNS handle power-up and power-down sequences?

The SN74BCT2827CNS features an inherent power-up high-impedance state: all outputs remain in 3-state regardless of OE input voltage until VCC stabilizes within specification. This prevents bus contention during brown-out or asymmetric power ramping. During power-down, outputs revert to high-Z before VCC drops below 2 V. This behavior is guaranteed across the full 0°C to 70°C range and is intrinsic to the BiCMOS design-not dependent on external circuitry. The SN74BCT2827CNS thus simplifies system power sequencing.