Texas Instruments SN74LS175D

Overview

SN74LS175D from Texas Instruments is a quadruple D-type flip-flop with asynchronous clear, implemented in low-power Schottky TTL logic. It features 4 independent edge-triggered storage elements, 16-pin SOIC package, guaranteed operation from 0°C to 70°C, and typical propagation delay of 15 ns at V_CC = 5 V. It serves as synchronous data latch and state register in legacy digital control systems.

For engineers reviewing the SN74LS175D datasheet, SN74LS175D pinout, SN74LS175D application, or SN74LS175D equivalent, this page delivers verified functional identity, validated pin assignments, confirmed timing parameters, documented package dimensions, and real-world substitution guidance for industrial retrofits and repair programs.

Technical Context

The SN74LS175D implements four identical positive-edge-triggered D-type flip-flops sharing a common clock (CLK) and asynchronous master clear (CLR̅) input. Each flip-flop samples its D input on the rising edge of CLK and updates Q output synchronously.

It operates strictly in TTL-compatible voltage domains: V_CC = 4.75–5.25 V, input high threshold ≈ 2.0 V, input low threshold ≈ 0.8 V, and drives standard TTL loads (I_OH = –0.4 mA, I_OL = 8 mA). No internal pull-ups, no Schmitt-trigger inputs, and no power-down mode are supported.

Key Specifications

Pinout & Package

SOIC-16 (D) package: 16-pin small-outline integrated circuit with gull-wing leads, 1.27 mm pitch, 7.5 mm width, and 10.3 mm length. RoHS-compliant NiPdAu lead finish, MSL Level-1, peak reflow 260°C.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar D-type flip-flop applications.

Compared with SN74LS175N, SN74LS175D offers surface-mount compatibility and smaller footprint; compared with SN74LS174DR, it provides unified asynchronous clear essential for coordinated state machine initialization-neither is pin-compatible, but both satisfy overlapping functional roles in discrete logic designs.

Availability

SN74LS175D is available at Aetrix Electronics and suitable for industrial control sequencing, digital test equipment, legacy computer bus interface, and repair & retrofit systems requiring stable component supply across long-lifecycle deployments.

Supply support for SN74LS175D 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 U.S.-based semiconductor company founded in 1930, specializing in analog and embedded processing technologies with broad industrial, automotive, and consumer product portfolios.

The SN74LS175D belongs to TI's legacy 74LS logic family, designed specifically for reliable, low-power implementation of synchronous digital state storage in cost-sensitive, non-programmable hardware systems.

FAQ

What is the maximum clock frequency supported by the SN74LS175D?

The SN74LS175D does not specify a maximum clock frequency in its datasheet. Its usable frequency is determined by propagation delay (15 ns max) and setup/hold time requirements (t_su = 20 ns, t_h = 0 ns). For reliable operation, clock periods must exceed 35 ns, implying a practical upper limit near 28 MHz under ideal loading and layout conditions. The SN74LS175D is intended for use in systems with moderate-speed synchronous logic, not high-frequency applications.

Does the SN74LS175D support power-down or tri-state outputs?

No, the SN74LS175D does not support power-down mode or tri-state (high-impedance) outputs. All Q and Q̅ outputs are push-pull and permanently enabled. Outputs cannot be disabled or isolated electrically without external gating. This design reflects its role as a basic storage element in fixed-function logic systems. The SN74LS175D requires continuous V_CC supply and always drives its outputs according to stored state and input conditions.

Can the SN74LS175D be used with 3.3 V logic systems?

No, the SN74LS175D is not compatible with 3.3 V logic systems. It requires a 4.75–5.25 V supply and is specified only for TTL-level input thresholds (V_IH ≥ 2.0 V, V_IL ≤ 0.8 V). Driving its inputs from 3.3 V CMOS outputs may result in marginal or unreliable high-level recognition. Interfacing with 3.3 V systems requires level translation. The SN74LS175D is strictly a 5 V device and must be powered and driven within its published 5 V TTL specifications.

Is the SN74LS175D pin-compatible with the SN74LS174 series?

No, the SN74LS175D is not pin-compatible with the SN74LS174 series. While both are 16-pin SOIC D-type flip-flops, the SN74LS174 is a hex (6-bit) device with individual clear inputs per flip-flop and different pin assignments (e.g., dedicated clear per stage rather than shared CLR̅). Pinouts differ fundamentally: SN74LS175D uses pin 1 for global CLR̅ and pins 13–16 for true Q outputs, whereas SN74LS174DR allocates pins for six separate clears and distinct output ordering. The SN74LS175D and SN74LS174DR serve different architectural needs and require PCB layout changes for substitution.

What is the meaning of ".A" suffix in SN74LS175DR.A?

The ".A" suffix in SN74LS175DR.A denotes a variant with identical electrical and functional specifications to SN74LS175DR but differing only in tape-and-reel packaging configuration-specifically, reel diameter, orientation, or carrier tape marking conventions. It is not a revision or performance upgrade. Both SN74LS175DR and SN74LS175DR.A are fully interchangeable in circuit design and operation. The SN74LS175D itself is obsolete, but SN74LS175DR and SN74LS175DR.A remain active production parts supporting ongoing demand.