Nexperia USA Inc. HEF4521BT-Q100J

Overview

HEF4521BT-Q100J from Nexperia is an automotive-qualified 24-stage CMOS frequency divider with integrated crystal/RC oscillator circuitry, operating from 3 V to 15 V supply, delivering division ratios up to 2²⁴ = 16,777,216, and providing seven selectable output stages (Q18–Q24) for flexible timing synthesis in engine control units and body electronics.

For engineers reviewing the HEF4521BT-Q100J datasheet, HEF4521BT-Q100J pinout, HEF4521BT-Q100J application, or HEF4521BT-Q100J equivalent, key selection criteria include its AEC-Q100 Grade 3 qualification, wide-voltage oscillator operation, asynchronous master reset behavior, and static CMOS logic compatibility with legacy 4000-series timing systems.

Technical Context

The device implements a cascaded chain of 24 toggle flip-flops advancing on the HIGH-to-LOW transition of input A2, with independent VDD1/VSS1 biasing enabling low-power crystal oscillator mode. Its three-mode clock input circuit supports crystal oscillation, external clock buffering, and RC-based oscillation using A1/A2 feedback.

Functional test mode partitions the counter into three parallel 8-stage sections via VSS1/VDD1 reconfiguration, allowing rapid verification of all 24 stages with only 255 + 1 pulses. Output drive strength and propagation delays scale predictably with supply voltage (5 V/10 V/15 V parametric ratings) and load capacitance per JEDEC JESD13-B.

Key Specifications

Pinout & Package

HEF4521BT-Q100J is housed in a plastic SO16 package (SOT109-1), 3.9 mm body width, 16-pin small outline format compatible with standard surface-mount assembly processes.

Key Features

Applications

Equivalent & Alternatives

The following parts are listed as comparable options for similar 24-stage frequency divider applications.

Compared with CD4521BE and 74HC4060, the HEF4521BT-Q100J uniquely combines AEC-Q100 Grade 3 qualification, 24-bit division depth, and isolated low-power oscillator circuitry-making it the sole choice for safety-critical automotive timing where long-interval accuracy and supply noise immunity are mandatory.

Availability

HEF4521BT-Q100J is available at Aetrix Electronics and suitable for automotive engine control units, body control modules, instrument clusters, and infotainment systems requiring stable component supply across extended temperature ranges and long product lifecycles.

Supply support for HEF4521BT-Q100J 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, reliable logic, discrete, and MOSFET components optimized for automotive, industrial, and mobile applications.

The HEF4521B-Q100 product line delivers AEC-Q100-qualified CMOS timing ICs designed specifically for automotive subsystems requiring long-interval, low-jitter frequency division with integrated oscillator flexibility.

FAQ

What oscillator configurations does HEF4521BT-Q100J support?

The device supports three distinct modes: (1) crystal oscillator using A2/Y2 with external crystal and load capacitors; (2) external clock buffer mode where A2 accepts TTL/CMOS signals directly; and (3) RC oscillator using A1/Y1 with external resistor and capacitor. VDD1/VSS1 pins must be configured per mode-crystal mode requires external bias resistors, while RC and buffer modes tie VDD1 to VDD and VSS1 to VSS.

How does the master reset (MR) interact with the counter states?

MR is an asynchronous active-HIGH input that forces all 24 flip-flop outputs (Q1–Q24) to logic LOW immediately, overriding any clock edge or internal state. It does not affect the oscillator circuit-A2 continues toggling if enabled-but resets only the counter chain. The reset is effective across the full -40 °C to +85 °C range and requires ≥15 ns minimum pulse width at 15 V.

Can HEF4521BT-Q100J operate from a 12 V automotive battery directly?

Yes-its 3 V to 15 V supply range covers nominal 12 V systems including cold-crank dips (~6 V) and load-dump transients (up to 14 V sustained). Internal CMOS structure ensures stable operation without external regulators; however, proper 100 nF ceramic + 10 μF tantalum decoupling at VDD/VSS is required per ISO 16750-2 EMC compliance.

What is the functional test mode used for?

The functional test mode reduces production test time by partitioning the 24-stage counter into three parallel 8-stage sections. This is achieved by connecting VSS1 to VDD and VDD1 to VSS, then loading 255 counts into each section via A2/Y2 interconnection. A single additional clock pulse then verifies ripple-through behavior from all-HIGH to all-LOW-confirming all 24 stages in <300 test cycles.