Nexperia USA Inc. 74HC191PW,118

Overview

74HC191PW,118 from Nexperia is a presettable synchronous 4-bit binary up/down counter in TSSOP16 package, featuring asynchronous parallel load (PL), synchronous count enable (CE), and dual-direction control via U/D input. It operates from 2.0 V to 6.0 V, delivers 39 MHz max frequency at 6.0 V, and provides terminal count (TC) and ripple clock (RC) outputs for multistage cascading - used in digital timing control, programmable logic sequencers, and industrial encoder interfaces.

For engineers reviewing the 74HC191PW,118 datasheet, 74HC191PW,118 pinout, 74HC191PW,118 application, or 74HC191PW,118 equivalent, key selection considerations include its asynchronous preset capability, TC/RC output behavior under up/down transitions, propagation delays across supply voltages (e.g., 21 ns CP→Qn at 6.0 V), and -40 °C to +125 °C temperature rating for industrial-grade reliability.

Technical Context

The 74HC191PW,118 implements four master/slave D-type flip-flops with internal steering logic to support synchronous counting and asynchronous parallel loading. Its CE input enables synchronous expansion by gating state changes on the LOW-to-HIGH clock edge, while U/D determines direction without requiring separate up/down clocks.

Terminal count (TC) asserts HIGH at 0 (count-down) or 15 (count-up), remaining latched until state change or U/D toggle; RC follows CP only when TC=HIGH and CE=LOW, enabling ripple-clocked multistage counters. Inputs include clamp diodes for overvoltage tolerance with current-limiting resistors.

Key Specifications

Pinout & Package

TSSOP16 plastic thin shrink small outline package (SOT403-1); 16-pin, 4.4 mm body width, 0.65 mm pitch; surface-mount, lead-free, RoHS-compliant.

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,118, the 74HC193PW,118 trades U/D simplicity for clock flexibility, while SN74LS191N sacrifices voltage range and power efficiency for TTL compatibility - making the 74HC191PW,118 optimal for modern low-voltage, low-power, and cascade-friendly counter applications.

Availability

74HC191PW,118 is available at Aetrix Electronics and suitable for industrial motor control, programmable logic sequencers, digital panel meters, and legacy bus address generation requiring stable component supply across extended temperature ranges.

Supply support for 74HC191PW,118 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 specializing in high-performance, energy-efficient logic, analog, and discrete components for automotive, industrial, and consumer markets.

The 74HC191 belongs to Nexperia's 74HC logic family - designed for pin-compatible replacement of legacy TTL counters with improved speed, lower power, and wider supply voltage tolerance in industrial control and instrumentation systems.

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-clean; it is intended solely as a status flag or enable signal. For clocking downstream stages, use the RC output - which is synchronized to CP and glitch-free when CE=LOW and TC=HIGH. Direct use of TC as a clock risks metastability and incorrect counting.

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 recommended setup/hold timing (tsu = 0 ns, th = -11 ns at VCC = 6.0 V), risking indeterminate counting direction on the next clock edge. The datasheet mandates U/D stability when CE or CP is HIGH - always latch U/D before asserting CE=LOW or ensure CP is LOW during U/D transitions.

Is the 74HC191PW,118 compatible with 3.3 V microcontroller GPIOs?

Yes. At VCC = 3.3 V, VIH = 2.31 V (min) and VIL = 1.09 V (max), fully compatible with standard 3.3 V CMOS logic levels. Outputs drive VOH ≥ 3.1 V and VOL ≤ 0.33 V at IOL = 4 mA, ensuring noise-immune interfacing with 3.3 V peripherals without level shifters.

How does the RC output behave when CE goes HIGH during counting?

When CE transitions HIGH, RC immediately goes HIGH (inactive) and remains HIGH regardless of subsequent CP edges or TC state. RC only pulses on CP edges when both TC=HIGH and CE=LOW. This behavior allows precise inhibition of ripple propagation - e.g., halting all downstream stages by pulling CE HIGH on the first counter.