Texas Instruments SN74BCT374DBR

Overview

SN74BCT374DBR from Texas Instruments is an octal edge-triggered D-type latch with 3-state outputs, designed for bus interfacing and register storage in 5-V TTL-compatible systems. It features a shared rising-edge clock (CLK), active-low output enable (OE), 8 independent D/Q channels, 48 mA low-level output drive, and operates within 4.5 V to 5.5 V supply range - enabling direct replacement of legacy 74LS374 in high-drive bus applications.

For engineers reviewing the SN74BCT374DBR datasheet, SN74BCT374DBR pinout, SN74BCT374DBR application, or SN74BCT374DBR equivalent, key selection criteria include its BiCMOS output architecture, 7 ns typical propagation delay (tPLH/tPHL), 3-state timing parameters (tPZH/tPLZ < 7 ns), and SSOP-20 package compatibility with space-constrained industrial control and data acquisition PCBs.

Technical Context

The SN74BCT374DBR implements eight synchronous D-type latches sharing one clock input and one global output-enable signal. Its BiCMOS output stage delivers TTL-compatible voltage levels with CMOS-input logic thresholds (VIH = 2 V min, VIL = 0.8 V max) and supports bidirectional bus driving via high-impedance state control.

Each channel latches data on the rising edge of CLK while OE determines whether Q outputs reflect stored data (OE = low) or enter high-Z (OE = high). Internal circuitry isolates OE from latch operation - allowing data loading and retention independent of output state - and clamping diodes protect inputs/outputs against transient overvoltage per HBM ±2000 V ESD rating.

Key Specifications

Pinout & Package

SN74BCT374DBR uses a 20-pin SSOP (Shrink Small Outline Package) with 0.65 mm lead pitch and nominal body size 7.20 mm × 5.30 mm. This surface-mount package supports automated assembly and provides thermal resistance RθJA = 84.4°C/W for board-level power dissipation management.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal latch applications.

Compared with SN74LS374N and SN74ACT374DW, SN74BCT374DBR uniquely balances TTL-compatible drive strength, BiCMOS efficiency, and SSOP-20 compactness - making it optimal for retrofitting legacy bus interfaces where space, heat, and fanout are constrained.

Availability

SN74BCT374DBR is available at Aetrix Electronics and suitable for industrial control panels, test equipment data acquisition modules, and programmable logic controller I/O expansion requiring stable component supply, long-term lifecycle support, and RoHS-compliant packaging.

Supply support for SN74BCT374DBR 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 specializing in analog, embedded processing, and logic solutions for industrial, automotive, and communications markets.

The SN74BCT374DBR belongs to TI's BCT (Bipolar-CMOS-Transistor) logic family, engineered to deliver TTL-compatible performance with reduced power consumption - specifically targeting high-drive, noise-tolerant bus interface applications in commercial-grade systems.

FAQ

What is the maximum clock frequency supported by the SN74BCT374DBR?

The SN74BCT374DBR supports a maximum clock frequency of 70 MHz under recommended operating conditions (VCC = 4.5 V to 5.5 V, TA = 0°C to 70°C). This is derived from its minimum pulse width (tw = 7 ns) and setup time (tsu = 6.5 ns), ensuring reliable edge-triggered latching without violating timing margins. The SN74BCT374DBR achieves this performance using BiCMOS output circuitry that combines speed advantages of bipolar transistors with CMOS input efficiency.

Does the SN74BCT374DBR require external pull-up resistors on its outputs?

No, the SN74BCT374DBR does not require external pull-up resistors on its outputs when used in 3-state bus-driving configurations. Its bipolar push-pull outputs actively drive both logic high and low states, delivering VOH ≥ 2.4 V at IOL = 48 mA and VOL ≤ 0.55 V - sufficient to meet TTL input thresholds directly. Pull-ups are unnecessary and may cause contention or excessive current draw when outputs are enabled.

Can unused inputs on the SN74BCT374DBR be left floating?

No, unused inputs on the SN74BCT374DBR must not be left floating. As a CMOS-input device, floating inputs can cause oscillation, increased power consumption, and potential damage due to undefined internal node voltages. All unused D, CLK, and OE inputs must be tied to either VCC or GND using direct connections or 10-kΩ pull-up/pull-down resistors - per TI's Implications of Slow or Floating CMOS Inputs application report.

What is the thermal resistance (RθJA) of the SN74BCT374DBR in its SSOP-20 package?

The SN74BCT374DBR in SSOP-20 (DB) package has a junction-to-ambient thermal resistance (RθJA) of 84.4°C/W, as specified in TI's official datasheet SCBS019D. This value assumes standard JEDEC 2-layer board conditions and informs thermal design for continuous operation - for example, at 60 mA total ICC, the junction temperature rise above ambient is approximately 5.1°C, well within safe limits for commercial-temperature operation.

How does the SN74BCT374DBR differ from the SN74ALS374 in terms of output drive capability?

The SN74BCT374DBR provides significantly higher output drive than the SN74ALS374: 48 mA (min) IOL vs. 24 mA (min) for the ALS variant. This enables the SN74BCT374DBR to drive heavier capacitive loads (up to 50 pF) and more TTL inputs simultaneously without signal degradation. Additionally, the BCT version uses BiCMOS outputs to reduce ICCZ quiescent current, whereas the ALS part relies on advanced low-power Schottky TTL with higher standby power consumption.