STMicroelectronics 74VHC594TTR

Overview

74VHC594TTR from STMicroelectronics is a high-speed CMOS 8-bit serial-in, parallel-out shift register with separate storage register and dual asynchronous clear inputs (SCLR, RCLR). It operates from 2V to 5.5V, delivers 4.2ns typical propagation delay at 5V, supports 135MHz max clock frequency, and features symmetrical 8mA output drive. It is used in LED matrix drivers, digital control interfaces, and data serialization for microcontroller GPIO expansion.

For engineers reviewing the 74VHC594TTR datasheet, 74VHC594TTR pinout, 74VHC594TTR application, or 74VHC594TTR equivalent, key selection criteria include dual-clock architecture (SCK/RCK), cascading via QH' output, input voltage tolerance up to 7V independent of VCC, power-down input protection, and ESD immunity of 2kV.

Technical Context

The 74VHC594TTR integrates two synchronized but independently controlled registers: an 8-bit shift register accepting serial data on SI with positive-edge-triggered SCK, and an 8-bit D-type storage register loaded on positive-edge-triggered RCK. Clear functions are asynchronous and pin-separated (SCLR resets shift register; RCLR resets storage register).

Its input structure accepts 0–7V regardless of VCC, enabling 5V-to-3V level translation without external circuitry. Output stages provide balanced |IOH| = IOL = 8mA (min) drive with low noise (VOLP ≤ 0.8V) and high noise immunity (VNIH/VNIL ≥ 28% VCC).

Key Specifications

Pinout & Package

TSSOP-16 package (JEDEC MO-153, 4.4mm × 5.0mm body, 0.65mm pitch), lead-free and RoHS-compliant.

Key Features

Applications

Equivalent & Alternatives

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

Compared with SN74HC595DR and 74LV595PW, the 74VHC594TTR uniquely provides independent shift/storage control, true 7V-tolerant inputs, and built-in QH' inversion - making it optimal for noise-immune, level-translation, and pipelined industrial control designs.

Availability

74VHC594TTR is available at Aetrix Electronics and suitable for LED display drivers, microcontroller I/O expansion, and industrial control interfaces requiring stable component supply, long-term lifecycle support, and RoHS-compliant TSSOP packaging.

Supply support for 74VHC594TTR 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, designing and manufacturing analog, digital, and mixed-signal ICs for automotive, industrial, and consumer markets.

The 74VHC594 belongs to ST's high-speed CMOS logic family, engineered for low-power, high-noise-immunity digital interfacing in space-constrained and thermally demanding applications.

FAQ

Can 74VHC594TTR operate reliably at 2.0V supply?

Yes. The device is fully specified down to VCC = 2.0V, with guaranteed VIH = 1.5V, VOL ≤ 0.1V at 50µA, and fMAX ≥ 70MHz (CL = 15pF). Propagation delay increases to 8.8ns (max) at 2V, but all DC and AC parameters remain valid per Table 5 and Table 7.

What is the purpose of the QH' output?

QH' is the inverted serial output of the QH stage, enabling direct cascading of multiple 74VHC594TTR devices without external inverters. When QH' from one device connects to SI of the next, data flows synchronously through the chain on each SCK edge, preserving bit order and eliminating added propagation delay.

Does the 74VHC594TTR support hot insertion when VCC = 0V?

Yes. Its power-down protection ensures inputs tolerate 0–7V regardless of VCC state. With VCC = 0V, IIK is limited to ±20mA (Table 4), and input leakage remains ≤±5µA (Table 6), preventing damage or back-powering of the supply rail during live insertion.

How does the dual-clear architecture improve system reliability?

SCLR and RCLR operate independently: SCLR resets only the shift register (preserving current QA–QH outputs), while RCLR clears only the storage register (blanking outputs without affecting shift register content). This prevents unintended display flicker or relay dropout during partial reinitialization sequences.