Diodes Incorporated 74AHCT594T16-13

Overview

74AHCT594T16-13 from Diodes Incorporated is an 8-bit serial-in, parallel-out shift register with separate 8-bit storage register and active-low asynchronous reset for both registers. It operates from 4.5V to 5.5V, features Schmitt-trigger inputs, push-pull outputs (Q0–Q7), and cascading output Q7S - used in microcontroller GPIO expansion for industrial control panels requiring synchronized data latching.

For engineers reviewing the 74AHCT594T16-13 datasheet, 74AHCT594T16-13 pinout, 74AHCT594T16-13 application, or 74AHCT594T16-13 equivalent, key selection criteria include dual-clock timing independence (SHCP/STCP), simultaneous active-low reset capability (SHR/STR), propagation delay ≤8.8 ns at 50 pF load, and TSSOP-16 package compatibility with high-density PCB layouts.

Technical Context

The device implements two independent synchronous registers: an 8-bit shift register clocked by SHCP (rising edge) and a storage register clocked by STCP (rising edge), with data transferred from shift to storage register on STCP's rising edge. Both SHR and STR are asynchronous, active-low, and electrically isolated from clock domains.

Input signals DS, SHCP, STCP, SHR, and STR all feature Schmitt-trigger action for noise immunity, accept up to 6.0V regardless of VCC, and exhibit input hysteresis ≥0.5V. Output drivers deliver ±8mA at VCC = 4.5V with VOH ≥3.70V and VOL ≤0.55V under full load.

Key Specifications

Pinout & Package

TSSOP-16 package: 4.9 mm × 6.4 mm body, 0.65 mm pitch, 1.08 mm max height, thermally enhanced for reflow-compatible assembly in space-constrained industrial modules.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 8-bit serial-in/parallel-out shift register applications.

Compared with SN74AHCT595PW and 74LV595PW, the 74AHCT594T16-13 uniquely provides dual asynchronous resets and Schmitt-trigger inputs - making it the only option among the three for deterministic, noise-immune I/O expansion in certified industrial equipment.

Availability

74AHCT594T16-13 is available at Aetrix Electronics and suitable for industrial PLC I/O expansion, LED matrix row driving, and microcontroller GPIO multiplexing requiring stable component supply, long-term lifecycle assurance, and RoHS-compliant TSSOP packaging.

Supply support for 74AHCT594T16-13 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

Diodes Incorporated is a global manufacturer of discrete semiconductors and analog ICs, specializing in high-reliability components for industrial, automotive, and computing markets with ISO/TS 16949 and IATF 16949 certification.

The 74AHCT594 belongs to Diodes' advanced high-speed CMOS logic family, designed specifically for drop-in replacement of legacy 74LS devices while delivering lower power, higher noise immunity, and extended temperature operation.

FAQ

Can SHCP and STCP be tied together for single-clock operation?

Yes - tying SHCP and STCP enables pipeline mode where the shift register is always one clock cycle ahead of the storage register. This configuration allows continuous serial data flow while maintaining stable parallel outputs, ideal for streaming sensor data acquisition. Timing margins must accommodate tPLH(STCP→Qn) + tSU(DS→SHCP) ≤ tW(SHCP), verified per Figure 2 in DS35485 Rev. 2-2.

What is the maximum capacitive load per output pin?

Each Q0–Q7 output supports up to 50 pF load capacitance while maintaining specified propagation delay (≤8.8 ns) and VOL (≤0.55V at 8mA). Exceeding 50 pF increases rise/fall times and may cause setup/hold violations in downstream logic; add series termination or buffer stages if driving long traces or multiple gate inputs.

How does Q7S differ from Q7 in cascading configurations?

Q7S is the true serial output of the shift register (MSB of shift stage), while Q7 is the parallel output of the storage register. In cascading, Q7S connects to DS of the next device - preserving shift register state across stages - whereas Q7 reflects latched data and cannot propagate uncommitted bits. This separation enables independent shifting and latching across multi-chip chains.

Is the 74AHCT594T16-13 suitable for 3.3V logic systems?

No - the 74AHCT594 requires minimum 4.5V VCC for guaranteed operation; VIH(min) = 2.0V and VIL(max) = 0.8V are defined only within 4.5V–5.5V supply range. Driving inputs from 3.3V logic violates recommended operating conditions and risks undefined output states; use level translators or select 74LVC594 for 3.3V-native designs.