Texas Instruments SN74LS373DWR

Overview

SN74LS373DWR from Texas Instruments is an octal D-type transparent latch with 3-state outputs, designed for bus-oriented systems. It features transparent latching (Q follows D while C is high), clock-enable input, buffered control inputs, and high-current 3-state outputs capable of driving capacitive or low-impedance loads - commonly used in address/data latching in 8-bit microprocessor systems such as those based on the Intel 8080 or Zilog Z80.

For engineers reviewing the SN74LS373DWR datasheet, SN74LS373DWR pinout, SN74LS373DWR application, or SN74LS373DWR equivalent, this device is selected for its reliable data hold timing (20 ns data hold time), TTL-compatible input thresholds, 24 mA low-level output drive, and SOIC-20 package suitability for space-constrained industrial control and legacy computing board designs.

Technical Context

The SN74LS373DWR implements eight independent transparent D latches sharing a common clock (C) and output-control (OC) signal. Its latch behavior is level-sensitive: Q outputs track D inputs when C is high, and hold the last value when C transitions low. The OC input operates asynchronously to place all eight outputs in high-impedance state without affecting internal latch states.

Input structure uses standard TTL-compatible P-N-P transistor inputs (no Schmitt-trigger hysteresis - that applies only to 'S373 variants). Output drivers are totem-pole with 3-state capability, enabling direct connection to shared data buses without external pull-ups or interface logic. Propagation delays are specified at 12–18 ns (data-to-Q) and 20–30 ns (clock-to-Q) under standard load conditions (RL = 667 Ω, CL = 45 pF).

Key Specifications

Pinout & Package

SN74LS373DWR is housed in a 20-pin SOIC (DW) package with 1.27 mm pitch, 7.5 mm body width, and standard JEDEC MS-013 outline. Pin numbering follows standard SOIC top-view convention (pin 1 marked by notch or dot).

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74LS373N, SN74LS373DWR offers superior thermal performance and surface-mount compatibility; compared with SN74LS374DWR, it provides fundamentally different (level-sensitive vs. edge-triggered) data capture behavior essential for bus-hold applications.

Availability

SN74LS373DWR is available at Aetrix Electronics and suitable for industrial control panels, legacy computing upgrades, and test equipment requiring stable component supply with long-term lifecycle support.

Supply support for SN74LS373DWR 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 with broad industrial and automotive reach.

The SN74LS373DWR belongs to TI's classic 74LS logic family, engineered for reliable, low-power TTL-compatible digital interfacing in cost-sensitive, high-reliability embedded systems deployed since the 1970s.

FAQ

What is the primary function of the SN74LS373DWR?

The SN74LS373DWR is an octal D-type transparent latch with 3-state outputs. Its core function is to capture and hold eight parallel data bits when the clock (C) input transitions low, while allowing outputs to be placed in high-impedance state via the active-low output-control (OC) signal. This makes SN74LS373DWR ideal for address/data latching in microprocessor buses and general-purpose register applications.

Does the SN74LS373DWR have Schmitt-trigger inputs?

No, the SN74LS373DWR does not include Schmitt-trigger inputs. Input hysteresis is present only in the 'S373 and 'S374 variants (e.g., SN74S373), not in the 'LS373 family. The SN74LS373DWR uses standard TTL-compatible P-N-P input structure with VIH = 2.0 V and VIL = 0.8 V, requiring clean, monotonic input transitions for reliable operation.

Can SN74LS373DWR replace SN74LS374DWR in a design?

No, SN74LS373DWR cannot directly replace SN74LS374DWR. The SN74LS373DWR is a transparent latch (level-sensitive enable), whereas SN74LS374DWR is an edge-triggered D flip-flop (positive-edge clocked). Their timing behavior, setup/hold requirements, and functional use cases differ fundamentally - substituting one for the other would require redesigning clocking and control logic in the system.

What is the maximum clock frequency supported by SN74LS373DWR?

The SN74LS373DWR supports a maximum clock frequency of 35 MHz under standard test conditions (VCC = 5 V, TA = 25°C, RL = 667 Ω, CL = 45 pF). This limit derives from propagation delays (20–30 ns C→Q) and pulse-width requirements (≥15 ns high/low time). For robust operation across temperature and voltage extremes, designs typically target ≤25 MHz with appropriate timing margins.

Is SN74LS373DWR RoHS compliant and lead-free?

Yes, SN74LS373DWR is RoHS compliant and features a lead-free NIPDAU (Nickel/Palladium/Gold) terminal finish. Per TI's packaging addendum, it carries MSL Level-1 rating (unlimited floor life at ≤30°C/60% RH) and is qualified for reflow per J-STD-020 at peak temperatures up to 260°C. The part marking "LS373" appears on the top surface of the SOIC-20 body.