Nexperia USA Inc. HEF4518BT,653

Overview

HEF4518BT,653 from Nexperia is a dual 4-bit internally synchronous BCD counter in SO16 package, featuring two independent clock inputs (CP0 LOW-to-HIGH triggered, CP1 HIGH-to-LOW triggered), asynchronous master reset (MR), buffered Q0–Q3 outputs per counter, and Schmitt-trigger clock inputs for tolerance to slow edge rates. It operates from 3.0 V to 15.0 V across -40 °C to +85 °C and is used in multistage synchronous counting and frequency division circuits.

For engineers reviewing the HEF4518BT,653 datasheet, HEF4518BT,653 pinout, HEF4518BT,653 application, or HEF4518BT,653 equivalent, this page delivers verified functional behavior, SO16 terminal mapping, BCD counting timing constraints, and validated alternatives for industrial timing and digital logic design.

Technical Context

The HEF4518BT,653 implements two independent 4-bit BCD counters with fully static CMOS architecture and internal synchronization. Each counter advances on either CP0↑ (when CP1 = HIGH) or CP1↓ (when CP0 = LOW), enabling flexible clock/enable configuration without external gating logic.

Schmitt-trigger inputs provide hysteresis (typ. 1.2 V at VDD = 5 V), ensuring reliable operation with slow-rising or noisy clock signals. The asynchronous MR input forces all eight outputs (Q0–Q3 of both counters) LOW regardless of clock state, supporting deterministic system initialization.

Key Specifications

Pinout & Package

HEF4518BT,653 is housed in a plastic small outline package (SO16), SOT109-1, with 16 leads, 3.9 mm body width, and standard 1.27 mm lead pitch. Pin 1 is marked by a notch or dot; pin numbering follows counterclockwise sequence from top-left corner when viewed with marking side up.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar dual BCD counter applications.

Compared with CD4018BE, HEF4518BT,653 provides native dual BCD counting without decode logic; versus 74HC390, it offers lower power at 15 V but lacks binary mode and has narrower temp rating-making it optimal for cost-sensitive industrial 5–15 V systems where strict BCD compliance is required.

Availability

HEF4518BT,653 is available at Aetrix Electronics and suitable for industrial multistage counting, programmable frequency division, and legacy system timing upgrades requiring stable component supply over extended temperature and voltage ranges.

Supply support for HEF4518BT,653 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 high-volume, high-reliability logic, analog, and discrete components, serving automotive, industrial, and consumer markets with ISO/TS 16949-certified manufacturing.

The HEF4518BT,653 belongs to Nexperia's legacy CMOS logic family designed for robust, wide-voltage industrial control applications where noise immunity, temperature stability, and long-term supply continuity are critical.

FAQ

Can HEF4518BT,653 operate reliably at 3.3 V?

Yes-its specified minimum supply voltage is 3.0 V, and static/dynamic characteristics are guaranteed across the full 3.0–15.0 V range. At 3.3 V, fmax drops to ~12 MHz (per datasheet Table 7 extrapolation), and output drive reduces to ±0.5 mA, which remains sufficient for driving modern CMOS loads with ≤30 pF capacitance.

How does the dual-clock architecture prevent race conditions during cascading?

The HEF4518BT,653 avoids race conditions by requiring complementary states on CP0 and CP1 for counting: one must be HIGH while the other transitions. When cascading, the Q3 output of the first counter drives CP0 of the second, while CP1 is held HIGH-ensuring only one edge per decade advance and eliminating metastability from simultaneous clock edges.

Is the SO16 (SOT109-1) package RoHS compliant and lead-free?

Yes-Nexperia confirms the HEF4518BT,653 is manufactured in full compliance with RoHS Directive 2011/65/EU and REACH Regulation (EC) No. 1907/2006. The SOT109-1 package uses lead-free matte tin (Sn) termination with NiPdAu underplate, and JEDEC moisture sensitivity level is MSL3 per J-STD-020.

What is the maximum capacitive load the Q outputs can drive without exceeding propagation delay specs?

Per Table 7, the typical propagation delay (tPLH/tPHL) is specified with CL = 50 pF. Exceeding this load increases delay linearly: e.g., at VDD = 10 V, tPLH = 24 ns + (0.23 ns/pF) × CL. To stay within the 70 ns max limit, CL must remain ≤ 200 pF. For stable operation beyond 50 pF, add series termination or buffer drivers.