STMicroelectronics 74LCX573TTR

Overview

74LCX573TTR from STMicroelectronics is a low-voltage CMOS octal D-type transparent latch with non-inverting 3-state outputs, 5V-tolerant I/O, and operation from 2.0V to 3.6V. It features 8.0 ns max propagation delay at VCC = 3V, ±24 mA output drive, symmetrical output impedance, and latch-enable + output-enable control logic-used in 3.3V bus interface and data buffering between mixed-voltage domains.

For engineers reviewing the 74LCX573TTR datasheet, 74LCX573TTR pinout, 74LCX573TTR application, or 74LCX573TTR equivalent, key selection criteria include 5V-tolerant I/O compatibility with legacy 5V systems, 3.3V core operation for low-power embedded buses, high-speed latch timing (tPLH ≅ tPHL), and guaranteed PCI bus-level drive at 24 mA.

Technical Context

The device implements a dual-control transparent latch architecture: LE (latch enable) determines data transparency vs. latching, while OE (output enable) independently controls 3-state output activation. All inputs and outputs tolerate 0–5.5V regardless of VCC (2.0–3.6V), enabling safe interfacing with 5V signal sources and sinks without level shifters.

It uses sub-micron C2MOS technology with double-layer metal wiring, delivering AC/ACT-family speed at 3.3V while consuming significantly less power. Propagation delays are balanced (tPLH ≅ tPHL), skew is ≤1.0 ns, and output impedance is symmetrical (|IOH| = IOL = 24 mA min at VCC = 3V), critical for clean bus signaling in high-density PCB layouts.

Key Specifications

Pinout & Package

TSSOP-20 package: 6.5 mm × 4.4 mm body, 0.65 mm pitch, thin-profile surface-mount with exposed pad not present. RoHS-compliant, moisture sensitivity level MSL3.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74LVC573APW and SN74LVCH16373A, the 74LCX573TTR uniquely combines full 5V-tolerant I/O, TSSOP-20 footprint, and guaranteed 24 mA drive at 3.3V-making it optimal for compact, mixed-voltage bus latching where pin compatibility and voltage robustness are mandatory.

Availability

74LCX573TTR is available at Aetrix Electronics and suitable for PCI bus interface, 3.3V/5V voltage translation, and memory address latching requiring stable component supply and long-term obsolescence management.

Supply support for 74LCX573TTR 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

STMicroelectronics is a global semiconductor leader headquartered in Geneva, designing and manufacturing analog, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.

The 74LCX logic family targets low-voltage, high-speed 3.3V systems with 5V-tolerant I/O-enabling seamless migration from 5V designs while reducing power and improving noise margins.

FAQ

Can 74LCX573TTR operate with VCC = 2.5V and still drive 5V-tolerant loads?

Yes. The device guarantees 5V-tolerant inputs and outputs across its full VCC operating range (2.0–3.6V). At VCC = 2.5V, VOH remains ≥2.0V (per VIH = 2.0V min), and VOL stays ≤0.4V (IOL = 12 mA), satisfying TTL and 5V CMOS input thresholds. Output voltage swing is referenced to VCC, but clamp diodes protect against overvoltage.

What is the minimum LE pulse width required for reliable latching at 3.3V?

The datasheet specifies tW(LE) = 3.3 ns minimum at VCC = 3.0–3.6V. This ensures sufficient setup time for internal metastability suppression. For robust operation across temperature and voltage corners, design with ≥5 ns LE pulse width and maintain monotonic LE edge rates below 10 ns/V per datasheet dt/dv limit.

Does 74LCX573TTR require external pull-up resistors on OE or LE pins?

No. Internal weak pull-downs are not present; OE and LE are standard CMOS inputs with ±5 µA leakage. External biasing is only needed if floating states must be avoided-e.g., tie OE to GND via 10 kΩ for default-enabled operation, or to VCC for default-disabled. No pull-ups are required for latch functionality.

How does power-down protection work when VCC = 0V?

When VCC = 0V, all inputs and outputs enter high-impedance state with diode-clamped protection. Input pins block current flow above GND–0.5V or below VCC+0.5V (i.e., –0.5V), preventing back-powering. Output pins similarly clamp to safe limits, allowing hot-plug or partial-power-down scenarios without damaging connected devices.