Nexperia USA Inc. 74HC191PW,112

Overview

74HC191PW,112 from Nexperia is a presettable synchronous 4-bit binary up/down counter in TSSOP16 package, featuring asynchronous parallel load (PL), synchronous count enable (CE), single up/down (U/D) control, and dual outputs - terminal count (TC) and ripple clock (RC). It operates from 2.0 V to 6.0 V across –40 °C to +125 °C and is used in digital timing, frequency division, and multistage counter cascading in industrial control panels.

For engineers reviewing the 74HC191PW,112 datasheet, 74HC191PW,112 pinout, 74HC191PW,112 application, or 74HC191PW,112 equivalent, key selection considerations include its asynchronous preset capability, TC/RC output behavior under up/down transitions, propagation delays at 4.5 V (e.g., CP→Qn = 26–44 ns), and compatibility with 3.3 V and 5 V logic systems.

Technical Context

The 74HC191PW,112 implements a master/slave flip-flop architecture with internal steering logic enabling true synchronous counting and asynchronous parallel loading. Its TC output goes HIGH at zero (count-down) or fifteen (count-up), while RC follows CP only when TC = HIGH and CE = LOW - enabling ripple-cascaded multistage counters without external gating.

Count direction is controlled solely by the U/D input, which must be stable when CE or CP is HIGH; CE must transition LOW only while CP is HIGH to avoid metastability. The device supports synchronous expansion via RC output chaining and avoids decoding spikes by prohibiting TC use as a clock signal.

Key Specifications

Pinout & Package

TSSOP16 plastic thin shrink small outline package (SOT403-1); 16-pin surface-mount; body width 4.4 mm; lead pitch 0.65 mm; moisture sensitivity level MSL3.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 4-bit synchronous up/down counter applications.

Compared with 74HC191PW,112, the 74HC193PW,112 trades RC-based synchronous expansion for independent clocking flexibility, while the SN74LV191APW sacrifices industrial temperature and ESD margin for speed and 3.3 V optimization - making the 74HC191PW,112 uniquely balanced for rugged, cascaded counter designs.

Availability

74HC191PW,112 is available at Aetrix Electronics and suitable for industrial PLC modules, automotive dashboard instrumentation, test equipment frequency dividers, and legacy panel meter upgrades requiring stable component supply across extended temperature ranges.

Supply support for 74HC191PW,112 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

Nexperia is a global semiconductor expert focused on efficiency, reliability, and sustainability - delivering high-performance logic, analog, and discrete components for automotive, industrial, and consumer markets.

The 74HC191PW,112 belongs to Nexperia's 74HC logic family, engineered for low-power, high-noise-immunity digital control in harsh environments - specifically targeting applications needing deterministic counting, presettable states, and multi-stage synchronization.

FAQ

Can the TC output be used as a clock signal for another counter stage?

No. The TC output is subject to decoding spikes and is not edge-cleaned - using it directly as a clock risks metastability or false triggering. The datasheet explicitly prohibits this. Instead, the RC output - which is gated by TC and CE and aligned to CP - is designed for reliable inter-stage clocking in ripple or synchronous cascades.

What happens if U/D is changed while CE is LOW and CP is HIGH?

Changing U/D while CE = LOW and CP = HIGH violates the setup/hold requirement and may cause indeterminate counting direction on the next CP edge. The datasheet specifies U/D must be stable when CE or CP is HIGH. Violation can result in skipped or repeated states, especially near terminal counts where TC behavior depends on prior U/D state.

Is the 74HC191PW,112 compatible with 3.3 V microcontroller GPIOs driving its inputs?

Yes. At VCC = 3.3 V, VIH(min) = 2.1 V and VIL(max) = 1.35 V per datasheet Table 7 - well within typical 3.3 V MCU output specs (VOH ≥ 2.6 V, VOL ≤ 0.4 V). No level-shifting is needed, and the integrated input clamp diodes provide overvoltage tolerance if needed.

How does the RC output behave when CE is HIGH?

When CE is HIGH, counting is inhibited and the RC output remains HIGH (inactive) regardless of CP or TC state. RC only pulses LOW on the rising edge of CP when both TC = HIGH and CE = LOW - ensuring RC acts exclusively as a synchronous carry/borrow signal, not a free-running clock.