Nexperia USA Inc. 74HC191DB,118

Overview

74HC191DB,118 from Nexperia is a presettable synchronous 4-bit binary up/down counter with asynchronous parallel load, count enable control, and dual overflow/underflow outputs (TC and RC). It operates from 2.0 V to 6.0 V, supports -40 °C to +125 °C ambient range, and features CMOS-level inputs, low power dissipation, and high noise immunity. It is used in digital timing, frequency division, and multistage counter systems requiring reversible counting and ripple-carry expansion.

For engineers reviewing the 74HC191DB,118 datasheet, 74HC191DB,118 pinout, 74HC191DB,118 application, or 74HC191DB,118 equivalent, key selection considerations include synchronous up/down direction control, asynchronous preset capability, TC/RC output behavior for cascading, propagation delays at 4.5 V (e.g., CP→Qn = 26–44 ns), and SO16 package compatibility with industrial control and instrumentation PCB layouts.

Technical Context

The 74HC191DB,118 implements a master/slave flip-flop architecture with internal steering logic to support synchronous count-up/count-down on the LOW-to-HIGH clock edge while allowing asynchronous parallel load via active-LOW PL. Its U/D input determines counting direction without requiring state-hold during transitions, provided CE or CP is HIGH when U/D changes.

Terminal count (TC) is active-HIGH and latches until a state change occurs; it enables the ripple clock (RC) output only when CE is LOW and TC is HIGH. RC is active-LOW and replicates the clock pulse for synchronous multistage expansion-enabling carry/borrow propagation without external gating in ripple-clocked configurations.

Key Specifications

Pinout & Package

74HC191DB,118 is supplied in SO16 (SOT109-1) plastic small outline package: 16-pin, 3.9 mm body width, gull-wing leads, standard JEDEC MS-012 footprint compatible with automated assembly.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74HC191DB,118, the 74HC193 lacks integrated direction control and RC-based expansion, while the SN74LS191N sacrifices wide voltage range, low power, and industrial temperature support for TTL-level compatibility - making the 74HC191DB,118 optimal for modern mixed-voltage, high-reliability counter subsystems.

Availability

74HC191DB,118 is available at Aetrix Electronics and suitable for industrial PLC timing modules, digital panel meter counting, test equipment frequency dividers, and legacy bus address decoding requiring stable component supply, long-term lifecycle assurance, and SO16 package compatibility.

Supply support for 74HC191DB,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 delivering high-performance, reliable, and efficient logic, analog, and discrete components for automotive, industrial, and consumer applications.

The 74HC191DB,118 belongs to Nexperia's 74HC high-speed CMOS logic family, designed specifically for robust, low-power, wide-voltage digital control and timing functions in harsh-environment embedded systems.

FAQ

Can 74HC191DB,118 operate reliably at 3.3 V supply?

Yes. The 74HC191DB,118 is fully specified from 2.0 V to 6.0 V, with guaranteed operation at 3.3 V across its full -40 °C to +125 °C temperature range. At 3.3 V, typical CP→Qn delay is ~35 ns and f_max exceeds 25 MHz, meeting requirements for most 3.3 V microcontroller peripheral interfaces and FPGA timing circuits.

What is the correct way to use TC and RC outputs together in a multistage counter?

TC must go HIGH (on overflow/underflow) and CE must be LOW for RC to replicate the CP input. In ripple-cascaded designs, connect RC of stage N to CP of stage N+1. To prevent spurious triggering, ensure CE of all downstream stages is held HIGH until the first stage's TC asserts, then release CE synchronously using TC as an enable gate.

Is the SO16 package of 74HC191DB,118 RoHS compliant and lead-free?

Yes. The 74HC191DB,118 in SOT109-1 (SO16) package is manufactured per RoHS Directive 2011/65/EU and is lead-free, halogen-free, and compliant with Nexperia's environmental specifications. The device carries the "Pb-free" marking and meets JEDEC J-STD-020 moisture sensitivity level MSL3.

Does 74HC191DB,118 support hot insertion or live-state loading?

No. While the device includes input clamp diodes for overvoltage protection, it is not designed for hot insertion. Applying VCC after signal inputs may cause latch-up or undefined states. Always power VCC and GND before applying logic signals, and observe recommended t_rec (recovery time) of 8 ns after PL deactivation before clocking.