NXP Semiconductors 74HC161DB,112

Overview

74HC161DB,112 from Nexperia is a synchronous presettable 4-bit binary counter with asynchronous master reset (MR), internal look-ahead carry, dual count-enable inputs (CEP/CET), and parallel load capability via PE/D0–D3. It operates from 2.0 V to 6.0 V, delivers TC output pulse width ≈ Q0 HIGH duration, and supports cascading up to n-bit counters. Used in digital timing control, address sequencing, and event counting circuits.

For engineers reviewing the 74HC161DB,112 datasheet, 74HC161DB,112 pinout, 74HC161DB,112 application, or 74HC161DB,112 equivalent, key selection criteria include asynchronous reset behavior, CP-to-TC propagation delay (min 20 ns @ VCC=6.0 V), parallel load timing (PE setup/hold per Fig. 12), and SO16 package thermal derating (12.4 mW/K above 110 °C).

Technical Context

The 74HC161DB,112 implements four edge-triggered D-type flip-flops with synchronous clocking on the positive-going edge of CP. Its look-ahead carry architecture enables deterministic TC assertion at terminal count (Q3Q2Q1Q0 = HHHH) only when CET = HIGH, decoupling carry generation from ripple delay.

Count enable logic requires both CEP and CET HIGH for increment operation; TC feeds forward to enable next-stage counting. Asynchronous MR overrides all inputs-including CP, PE, and CE-forcing Q0–Q3 LOW immediately, independent of clock phase or enable state.

Key Specifications

Pinout & Package

74HC161DB,112 is supplied in SO16 (SOT109-1) plastic small outline package: 16-pin, 3.9 mm body width, gull-wing leads, JEDEC MS-012 compliant. Thermal resistance θ_JA = 80.6 K/W; total power dissipation derates linearly at 12.4 mW/K above 110 °C.

Key Features

Applications

Equivalent & Alternatives

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

Compared with 74HC161DB,112, the 74HC163DB,112 trades asynchronous reset determinism for synchronous control integrity, while SN74HC161N retains full functional equivalence but sacrifices thermal performance and board space efficiency in SMT designs.

Availability

74HC161DB,112 is available at Aetrix Electronics and suitable for industrial motor control, programmable logic sequencing, and embedded timing applications requiring stable component supply across extended temperature ranges.

Supply support for 74HC161DB,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 delivering high-performance logic, analog, and discrete components with focus on reliability, efficiency, and sustainability.

The 74HC161DB,112 belongs to Nexperia's 74HC logic family - engineered for low-power, high-noise-immunity digital control in industrial, automotive (non-safety), and consumer systems.

FAQ

What is the function of the TC output and how is it timed?

The TC (terminal count) output goes HIGH when the counter reaches 15 (Q3Q2Q1Q0 = HHHH) and CET is HIGH. Its pulse width approximates the HIGH duration of Q0, as confirmed in Fig. 9 and Section 6. This timing enables reliable cascading: TC can directly drive CP of the next counter stage without additional gating logic.

Can 74HC161DB,112 operate reliably at 3.3 V supply?

Yes - the 74HC161DB,112 is fully specified from 2.0 V to 6.0 V. At VCC = 3.3 V, typical propagation delays are 28–35 ns (CP to Qn), VIH = 2.31 V min, and VOL ≤ 0.26 V at 4 mA load, meeting standard 3.3 V LVTTL interface requirements without level translation.

How does the asynchronous MR differ from synchronous reset alternatives?

MR forces Q0–Q3 LOW immediately, independent of CP edge or enable states - verified by t_pd(MR→Qn) = 18–54 ns across voltage/temperature. In contrast, synchronous reset (e.g., 74HC163) requires a valid CP edge and active enables, introducing up to one clock cycle of latency before reset completion.

Is parallel loading affected by count enable inputs?

No - parallel loading occurs on the rising CP edge whenever PE = LOW, regardless of CEP or CET logic levels. This is explicitly stated in Section 1: "Preset takes place regardless of the levels at count enable inputs (CEP and CET)." The function table (Table 3) confirms load mode (H ↑ X X l h) is independent of CE states.