STMicroelectronics 74LVX594TTR

Overview

74LVX594TTR from STMicroelectronics is a low-voltage CMOS 8-bit serial-in/parallel-out shift register with output register, featuring 5V-tolerant inputs, 2V–3.6V operation, 5.5ns typical propagation delay at 3.3V, 4µA max quiescent current, and symmetrical 4mA output drive. It enables level-shifting in mixed-voltage systems such as 5V-to-3.3V microcontroller I/O expansion.

For engineers reviewing the 74LVX594TTR datasheet, 74LVX594TTR pinout, 74LVX594TTR application, or 74LVX594TTR equivalent, key selection criteria include input voltage tolerance, dual-clock architecture (SCK/RCK), independent clear inputs (SCLR/RCLR), serial cascade capability via QH', and TSSOP-16 packaging for high-density PCB layouts.

Technical Context

The device integrates two synchronized but independently controlled registers: an 8-bit shift register accepting serial data on SI with positive-edge-triggered SCK and asynchronous SCLR, and an 8-bit storage register capturing parallel outputs on positive-edge RCK with dedicated RCLR. Both clocks can be tied together to achieve pipeline delay-shift register state always leads storage register by one clock cycle.

Input protection supports 0–7V input voltage regardless of VCC, enabling robust interfacing between 5V logic and 3.3V domains. All I/Os feature 2kV ESD immunity, low-noise VOLP = 0.3V (typ.), and balanced |IOH| = IOL = 4mA (min) drive strength across the full operating range.

Key Specifications

Pinout & Package

TSSOP-16 package: 4.4mm × 5.0mm body, 0.65mm pitch, 1.2mm height, lead-free and RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit shift-and-latch register applications.

Compared with SN74LV8154N and 74HC595PW, the 74LVX594TTR uniquely delivers 5V-tolerant inputs, dual independent clears, and <6ns propagation delay in a compact TSSOP-16 - making it optimal for space-constrained, mixed-voltage, high-speed I/O expansion where deterministic timing and robust interfacing are critical.

Availability

74LVX594TTR is available at Aetrix Electronics and suitable for LED display drivers, microcontroller GPIO expanders, industrial PLC output modules, and automated test equipment requiring stable component supply and long-term lifecycle support.

Supply support for 74LVX594TTR 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, Switzerland, delivering innovative silicon solutions for automotive, industrial, and consumer markets since 1987.

The 74LVX series targets low-voltage, low-power, and mixed-signal interface applications - specifically engineered for 3.3V systems needing 5V compatibility, high noise immunity, and minimal power consumption without sacrificing speed.

FAQ

Can 74LVX594TTR operate with VCC = 2.0V and still meet timing specifications?

Yes. The device is fully specified down to 2.0V: fMAX = 60MHz (min) and tPD = 10.0ns (max) at -40°C to +85°C under 2.7V conditions, and all DC parameters including VIH/VIL thresholds remain guaranteed across the full 2.0–3.6V range per Table 5 and Table 6.

What happens to QA–QH outputs when RCLR is asserted low while SCK is active?

QA–QH go low immediately and remain latched low until RCLR is deasserted and a subsequent RCK rising edge transfers new data from the shift register. SCK activity continues shifting data internally but has no effect on QA–QH until RCK triggers the next load.

Is QH' truly inverted, or is it just the complement of QH?

QH' is the true logical complement of QH - verified in Figure 2's input equivalent circuit and confirmed by the truth table: when QH = HIGH, QH' = LOW, and vice versa. It is not delayed or buffered differently than QH; both share identical propagation characteristics per Table 8.

Does the 74LVX594TTR require external pull-up or pull-down resistors on unused inputs?

No. All inputs have internal protection diodes and leakage is limited to ±1µA (max) at VI = 5V or GND per Table 6. Unused inputs may be left floating only if system-level ESD and noise immunity are not critical; best practice remains tying unused SCLR/RCLR to VCC via 10kΩ for predictable reset behavior.