Texas Instruments SN74BCT574DBRG4

Overview

SN74BCT574DBRG4 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. Its primary role is as a bidirectional bus buffer/register in industrial control and legacy computing I/O subsystems.

For engineers reviewing the SN74BCT574DBRG4 datasheet, SN74BCT574DBRG4 pinout, SN74BCT574DBRG4 application, or SN74BCT574DBRG4 equivalent, key selection criteria include 3-state output timing (tPZL = 3.7 ns typ), BiCMOS power efficiency (ICCZ = 4.9 mA max), high-impedance isolation during OE assertion, and SOIC-20 package compatibility with legacy PCB layouts.

Technical Context

This device implements eight independent D-type flip-flops synchronized to the rising edge of CLK, with each Q output reflecting the corresponding D input state at clock transition. The buffered OE input controls all eight outputs simultaneously, enabling high-impedance (Z) state without affecting internal latch operation or data retention.

Its BiCMOS architecture combines bipolar speed and CMOS low quiescent current, delivering 77 MHz maximum clock frequency and reduced ICCZ versus standard TTL. Input thresholds (VIH = 2 V min, VIL = 0.8 V max) and output drive (IOL = 64 mA, IOH = −15 mA) ensure robust interfacing with both TTL and CMOS logic families across 0°C to 70°C ambient.

Key Specifications

Pinout & Package

SN74BCT574DBRG4 uses a 20-pin SSOP (Shrink Small Outline Package) with 0.65 mm lead pitch and 7.2 mm × 5.3 mm body size. Pin 1 is marked by a beveled corner; the package is RoHS-compliant with NiPdAu lead finish and MSL Level-1 rating.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar octal D-type flip-flop with 3-state output applications.

Compared with SN74ACT574N and 74F574SC, SN74BCT574DBRG4 uniquely balances 64 mA drive, 77 MHz speed, and 4.9 mA ICCZ in a RoHS-compliant SSOP package-making it optimal for space-constrained industrial I/O where bus loading and ESD resilience are critical.

Availability

SN74BCT574DBRG4 is available at Aetrix Electronics and suitable for industrial PLC I/O modules, legacy computer bus interfaces, and automated test fixture controllers requiring stable component supply and long-term obsolescence mitigation.

Supply support for SN74BCT574DBRG4 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 SN74BCT574DBRG4 belongs to TI's BCT (Bipolar-CMOS-Transistor) logic family, engineered specifically for high-speed, high-drive 5 V bus interface applications where TTL compatibility and low standby current are jointly required.

FAQ

What is the recommended power supply decoupling for SN74BCT574DBRG4?

Place a 0.1 µF ceramic capacitor between VCC (pin 10) and GND (pin 9), located within 5 mm of the SN74BCT574DBRG4 package. For systems with multiple SN74BCT574DBRG4 devices, add a 4.7 µF tantalum capacitor per 5–10 ICs on the same 5 V rail. This configuration suppresses switching noise and maintains stable VCC during simultaneous output transitions, preventing metastability or false clock triggering in the SN74BCT574DBRG4.

Can SN74BCT574DBRG4 operate reliably at 4.5 V minimum supply?

Yes, SN74BCT574DBRG4 is fully specified down to 4.5 V: VIH remains ≥2 V, VOL stays ≤0.55 V at IOL = 64 mA, and tPLH/tPHL meet 10 ns max across 0°C to 70°C. At 4.5 V, clock frequency drops to 70 MHz (vs. 77 MHz at 5 V), but all timing margins-including tsu = 4.5 ns and th = 0 ns-are preserved. This makes SN74BCT574DBRG4 suitable for brown-out tolerant industrial designs where 5 V rails may sag transiently.

How does OE pin behavior affect data retention in SN74BCT574DBRG4?

The OE pin in SN74BCT574DBRG4 has no effect on internal flip-flop states: data latched at the last CLK↑ edge remains stored regardless of OE logic level. When OE = H, outputs go high-Z while Q values persist internally-allowing new D inputs to be loaded on subsequent clocks without disturbing retained data. This enables seamless handshaking in multi-cycle bus protocols and eliminates need for external hold registers when using SN74BCT574DBRG4 in pipeline architectures.

Is SN74BCT574DBRG4 pin-compatible with other 20-pin octal D flip-flops?

SN74BCT574DBRG4 shares identical pinout with SN74LS574N, SN74ALS574N, and SN74F574N in PDIP/SOIC packages-same 1D–8D, CLK, OE, GND, VCC, and 1Q–8Q assignments. However, SSOP-20 (DB) footprint differs from PDIP-20 (N) and SOIC-20 (DW) in pad layout and pitch. Always verify land pattern against DW0020A mechanical drawing before PCB layout, as SN74BCT574DBRG4 requires 0.65 mm pitch, not 1.27 mm.

What is the maximum capacitive load SN74BCT574DBRG4 can drive while maintaining timing specs?

SN74BCT574DBRG4 is characterized at CL = 50 pF for all switching parameters (tPLH, tPHL, tPZH, etc.). Driving >50 pF increases propagation delays nonlinearly-e.g., tPLH rises from 2.2 ns (typ) to 4.1 ns at 100 pF. For reliable 77 MHz operation, limit total load (including trace + stub + receiver inputs) to ≤40 pF. Use series termination or reduce fanout if CL exceeds this; SN74BCT574DBRG4 itself contributes only 7.5 pF (Co), so system-level capacitance must be carefully budgeted.