Texas Instruments SN74BCT574N

Overview

SN74BCT574N from Texas Instruments is an octal transparent D-type flip-flop with 3-state outputs, designed for bus interface and data latching in TTL-compatible systems. It operates at 4.5 V to 5.5 V, features edge-triggered clocking on CLK↑, and supports 128 mA low-level output drive per channel. Used in I/O port buffering and bidirectional bus driving where high-impedance isolation is required.

For engineers reviewing the SN74BCT574N datasheet, SN74BCT574N pinout, SN74BCT574N application, or SN74BCT574N equivalent, key selection criteria include its 3-state enable timing (tPZH = 1 ns min), BiCMOS process advantages over standard TTL, and PDIP-20 package compatibility with legacy through-hole designs.

Technical Context

This device implements eight independent D-type flip-flops synchronized to the rising edge of CLK, with asynchronous 3-state control via OE. Each output can be driven to logic high, low, or high-impedance-enabling shared bus architectures without external pull-ups or interface components.

Its BiCMOS design reduces ICCZ (quiescent supply current) versus bipolar-only equivalents while maintaining TTL-level input thresholds (VIH = 2 V min, VIL = 0.8 V max) and delivering 77 MHz maximum clock frequency at VCC = 5 V and TA = 25°C.

Key Specifications

Pinout & Package

SN74BCT574N uses a 20-pin plastic dual in-line package (PDIP-N) with 0.3-inch body width and through-hole mounting. Pin 1 is marked by a notch or dot; pin numbering follows standard counter-clockwise layout from top view.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74ACT574N and SN74LS374N, the SN74BCT574N uniquely balances high-speed bus driving (77 MHz, 128 mA), BiCMOS power efficiency, and industrial-grade ESD protection-making it optimal for demanding 5 V bus interface roles where both performance and ruggedness matter.

Availability

SN74BCT574N is available at Aetrix Electronics and suitable for industrial control systems, legacy equipment repair, and embedded data acquisition requiring stable component supply across extended production lifecycles.

Supply support for SN74BCT574N 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 SN74BCT574N belongs to TI's BCT logic family, engineered to deliver TTL-compatible performance with BiCMOS efficiency-targeting high-reliability bus interface and data latching in mission-critical 5 V systems.

FAQ

What is the maximum clock frequency supported by the SN74BCT574N?

The SN74BCT574N supports a maximum clock frequency of 77 MHz under recommended operating conditions (VCC = 5 V, TA = 25°C). This value is measured with CL = 50 pF and reflects the device's ability to reliably capture data on each rising edge of CLK without violating setup or hold timing margins. At elevated temperatures or reduced supply voltages, the usable frequency may decrease slightly due to propagation delay variations.

How does the OE pin function on the SN74BCT574N?

The OE (output enable) pin on the SN74BCT574N is an active-low control that places all eight Q outputs into a high-impedance state when asserted high. When OE is low, outputs reflect the latched D-input values. Critically, OE does not affect internal flip-flop operation-data can be updated or retained while outputs remain disabled. For safe power-up behavior, TI recommends tying OE to VCC via a pullup resistor.

Is the SN74BCT574N pin-compatible with older 74-series latches like the 74LS374?

Yes, the SN74BCT574N is pin-compatible with the 74LS374 and 74ALS574 in the PDIP-20 package: all share identical pin assignments for CLK, OE, D inputs (1D–8D), Q outputs (1Q–8Q), VCC, and GND. However, SN74BCT574N offers superior electrical performance-including faster timing, higher drive strength, and lower ICCZ-making it a functional upgrade without layout changes.

What is the purpose of the BiCMOS design in the SN74BCT574N?

The BiCMOS architecture in the SN74BCT574N combines bipolar transistors for high-speed switching and CMOS for low static power consumption. This hybrid design significantly reduces ICCZ (quiescent supply current) compared to pure bipolar TTL equivalents while retaining TTL-compatible input thresholds and robust output drive. The result is improved power efficiency in systems with frequent bus idle periods.

Can the SN74BCT574N drive heavy capacitive loads directly?

Yes, the SN74BCT574N is specifically designed to drive highly capacitive or low-impedance loads. Its 128 mA low-level output current rating and fast 3-state enable/disable times (tPZH = 1 ns min, tPLZ = 1.3 ns min) allow direct connection to buses with >100 pF total capacitance without external buffers. TI confirms this capability in the device description and recommends it for buffer registers and bidirectional bus driver applications.