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Home > Products > Integrated Circuits (ICs) > Logic > Counters, Dividers

Nexperia USA Inc. HEF4521BT,653

Name: HEF4521BT,653
Brand: Nexperia USA Inc.
SKU: HEF4521BT,653
Price: 2.40 USD
Availability: InStock
Rating: 5 (2 reviews)

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Part No.:: HEF4521BT,653

Manufacturer:: Nexperia USA Inc.

Category:: Counters, Dividers

Package:: 16-SOIC (0.154", 3.90mm Width)

Datasheet:: HEF4521BT,653.pdf

Description:: IC DIVIDER BY 2 24-BIT 16SO

Quantity:: RFQ Add To RFQ list

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Product details

Overview

HEF4521BT,653 from Nexperia is a 24-stage CMOS binary frequency divider with integrated crystal/RC oscillator circuitry and asynchronous master reset. It delivers precise division ratios up to 2²⁴ = 16,777,216, operates from 3 V to 15 V, and provides seven selectable output stages (Q18–Q24) for flexible timing distribution in low-power clock generation systems.

For engineers reviewing the HEF4521BT,653 datasheet, HEF4521BT,653 pinout, HEF4521BT,653 application, or HEF4521BT,653 equivalent, key selection criteria include its wide VDD range (3–15 V), crystal oscillator capability with external resistor biasing, static operation, and -40 °C to +85 °C industrial temperature rating.

Technical Context

The HEF4521BT,653 implements a cascaded chain of 24 toggle flip-flops, advancing on the HIGH-to-LOW transition of the A2 input clock. Its input circuit supports three modes: crystal oscillator (with VDD1/VSS1 bias resistors), external oscillator buffer, or RC oscillator (using A1/A2 with external R/C network).

Each stage divides by two, yielding Q18 = 2¹⁸, Q24 = 2²⁴; outputs Q18–Q24 are individually accessible. The device features fully static CMOS logic, JEDEC JESD13-B compliance, and ESD protection exceeding 2000 V HBM and 1000 V CDM.

Key Specifications

Parameter	Value and Actual Design Meaning
Division Stages	24-stage binary counter; enables precise sub-harmonic generation down to 1/16,777,216 of input frequency
Supply Voltage Range	3 V to 15 V; supports direct interface with 5 V, 10 V, and 15 V logic domains without level shifting
Operating Temperature	-40 °C to +85 °C; qualified for industrial environments without derating
Max Input Frequency (A1)	35 MHz at VDD = 15 V; defines upper limit for external clock source driving oscillator input
Propagation Delay (A2→Q18)	440 ns max at VDD = 15 V, CL = 50 pF; determines worst-case latency from clock input to first usable divided output
Output Drive Strength	±3.6 mA at VDD = 15 V; sufficient to drive 50 pF loads directly or fan out to multiple CMOS inputs
Quiescent Supply Current	600 μA max at VDD = 15 V, Tamb = +85 °C; enables low-power battery-backed timing applications

Pinout & Package

HEF4521BT,653 is housed in a plastic SO16 (SOT109-1) package: 16-pin small outline, 3.9 mm body width, gull-wing leads, JEDEC MS-012 compliant.

Pin/Terminal	Circuit Role	Design Meaning
1	Q24	2²⁴ output (16,777,216× division); highest-resolution timing tap
2	MR	Asynchronous master reset; active LOW, overrides all counter states immediately
3	VSS1	Ground reference for crystal oscillator bias network; separate from main VSS
4	Y2	Inverting output of oscillator stage; used as feedback for crystal or RC configuration
5	VDD1	Supply for crystal oscillator bias network; isolated from main VDD to enable low-power mode
6	A2	Main clock input; counter advances on HIGH-to-LOW transition; also used for functional test mode
7	Y1	Inverting output of A1 input stage; provides buffered inverted signal for external use
8	VSS	Main digital ground; must be connected to system common reference
9	A1	Secondary oscillator input; used with A2 for RC oscillator or external clock buffering
10–15	Q18–Q23	Intermediate division outputs (2¹⁸ to 2²³); support multi-rate clock distribution
16	VDD	Main supply voltage; powers all 24 flip-flops and logic; decoupling required near pin

Key Features

Feature	Design Value
Triple-mode oscillator circuit	Supports crystal, external clock, or RC configurations-enables one IC to replace discrete oscillator + divider designs
Low-power crystal operation	VDD1/VSS1 biasing reduces oscillator current; extends battery life in portable timing applications
Seven dedicated output taps	Q18–Q24 provide independent division ratios (262k to 16.8M), eliminating need for external dividers
Wide voltage compatibility	3–15 V operation allows direct integration into mixed-voltage systems without regulators or translators
Industrial temperature range	-40 °C to +85 °C rating ensures stable timing performance across harsh environmental conditions

Applications

Frequency Synthesis for Test Equipment

Low-Power Real-Time Clock (RTC) Reference

Use Scenario: Generating precise sub-harmonics (e.g., 1 Hz, 10 Hz, 1 kHz) from a 1 MHz crystal in automated test fixtures.

IC Role / Device Role / Timing Role: Primary frequency divider and oscillator; replaces discrete crystal oscillator + 74HC393 cascade.

Use Value: Reduces BOM count by 3–4 components; eliminates timing skew between oscillator and first divider stage.

Use Scenario: Providing ultra-low-power 1 Hz timebase for microcontroller-based RTCs in battery-powered IoT sensors.

IC Role / Device Role / Timing Role: Standalone oscillator + divider; uses VDD1/VSS1 biasing to minimize quiescent current.

Use Value: Achieves <1 µA total system sleep current when paired with low-leakage MCU; extends 10-year battery life.

Programmable Logic Timing Generator

Legacy Industrial Control System Clock Scaling

Use Scenario: Deriving multiple synchronized clocks (e.g., 100 kHz, 12.5 kHz, 1.5625 kHz) for FPGA I/O banks and state machines.

IC Role / Device Role / Timing Role: Fixed-ratio clock tree generator; Q18–Q24 outputs routed to different logic domains.

Use Value: Eliminates need for PLL reconfiguration; guarantees deterministic phase relationships across all outputs.

Use Scenario: Adapting modern 10 MHz system clocks to legacy PLC modules requiring 390.625 Hz or 12.207 kHz timing references.

IC Role / Device Role / Timing Role: Drop-in replacement for obsolete CD4060-based timing circuits in field-upgraded control panels.

Use Value: Maintains pin-compatible upgrade path while improving noise immunity and supply voltage flexibility.

Equivalent & Alternatives

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

Alternative Part	Technical Difference	Application Difference	Selection Advice
CD4060BM96	14-stage counter only; no Q18–Q24 outputs; requires external crystal load capacitors	Limited to ≤2¹⁴ division; insufficient for 16.8M ratio; lower ESD tolerance (1500 V HBM)	Select only if division depth ≤16,384 suffices and cost is primary constraint
74HC4060PW,118	14-stage counter; same oscillator topology but lacks VDD1/VSS1 low-power bias option	No dedicated low-power crystal mode; higher IDD at 3 V; not rated for 15 V operation	Prefer for 5 V-only systems where power consumption is secondary to footprint

Compared with CD4060BM96 and 74HC4060PW,118, the HEF4521BT,653 uniquely delivers 24-bit division depth, seven simultaneous output taps, and configurable low-power crystal operation-making it the sole choice for high-ratio, multi-rate, and battery-sensitive timing applications.

Availability

HEF4521BT,653 is available at Aetrix Electronics and suitable for industrial automation timing, battery-powered sensor nodes, legacy equipment upgrades, and precision test instrumentation requiring stable component supply across extended product lifecycles.

Supply support for HEF4521BT,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 delivering high-performance, reliable, and energy-efficient components for automotive, industrial, computing, consumer, and communications markets.

The HEF4521B belongs to Nexperia's legacy CMOS logic portfolio, designed specifically for robust, wide-voltage-range timing and frequency division in industrial control, instrumentation, and legacy system modernization.

FAQ

What oscillator configurations does the HEF4521BT,653 support?

The HEF4521BT,653 supports three distinct oscillator modes: (1) crystal oscillator using A2/Y2 with external crystal and VDD1/VSS1 bias resistors; (2) external clock buffer via A2 input; and (3) RC oscillator using A1/A2 with external resistor and capacitor. Each mode is selected by external component connections-not internal registers-ensuring deterministic startup and no firmware dependency.

Can unused inputs be left floating?

No. All unused inputs-including MR, A1, A2, Y1, and Y2-must be tied to VDD, VSS, or another driven input. Floating CMOS inputs cause increased supply current, unpredictable logic states, and potential latch-up due to intermediate voltage levels violating noise margins. This requirement is explicitly stated in Section 1 of the datasheet and applies across the full -40 °C to +85 °C operating range.

How does the functional test mode work?

The functional test mode partitions the 24-stage counter into three independent 8-stage sections by connecting VSS1 to VDD and VDD1 to VSS. Then, 255 pulses are applied to A2 (with Y2 looped back as input) to preload each section with all HIGH states. Returning VSS1 to VSS and VDD1 to VDD restores full 24-stage operation; a single additional A2 pulse triggers a verified ripple-through to all LOW, confirming correct inter-stage connectivity and propagation delay.

Is the HEF4521BT,653 suitable for automotive applications?

No. The HEF4521BT,653 is specified only for industrial temperature range (-40 °C to +85 °C) and carries no AEC-Q100 qualification. Nexperia explicitly states in Section 16 that non-automotive qualified products "are not suitable for use in life support, life-critical or safety-critical systems" and lack automotive-grade reliability testing, screening, or failure rate validation. Automotive designs require purpose-qualified alternatives.

HEF4521BT,653 Specifications

Product attributes: Attribute value

Manufacturer:: Nexperia USA Inc.

Series:: 4000B

Package/Case:: 16-SOIC (0.154", 3.90mm Width)

Packaging:: Tape & Reel (TR)

Product Status:: Active

Logic Type:: Divide-by-2

Direction:: -

Number of Elements:: 1

Number of Bits per Element:: 24

Reset:: Asynchronous

Timing:: -

Count Rate:: 35 MHz

Trigger Type:: Negative Edge

Voltage - Supply:: 3 V ~ 15 V

Operating Temperature:: -40°C ~ 85°C

Grade:: -

Qualification:: -

Mounting Type:: Surface Mount

Supplier Device Package:: 16-SO

HEF4521BT,653 FAQ

1.How can I place an order for HEF4521BT,653 through Aetrix?

Please submit a Request for Quotation (RFQ) for HEF4521BT,653 on Aetrix. Our sales agent will provide a competitive quotation and guide you through the order confirmation once you accept the terms.

2.Are the price and stock information for HEF4521BT,653 reliable?

The price and inventory of HEF4521BT,653 are updated periodically and may fluctuate due to market conditions. Stock and pricing data are typically refreshed every 24 hours. Quotation validity for HEF4521BT,653 is usually 5 days.

3.What payment methods are accepted for HEF4521BT,653?

We accept Wire Transfer, PayPal, Credit Card, Western Union, MoneyGram, and Escrow for HEF4521BT,653 transactions.

Note: Certain payment methods may incur a processing fee.

4.How is shipping managed for HEF4521BT,653?

HEF4521BT,653 orders can be shipped via leading logistics carriers, including DHL, UPS, FedEx, TNT, or Registered Mail.

Once your HEF4521BT,653 order is processed, you will receive an email with the shipment details and tracking number.

Note: Tracking information may take up to 24 hours to appear. Express delivery typically takes 3–5 business days.

5.How can I obtain technical support or documentation for HEF4521BT,653?

For technical support, including HEF4521BT,653 datasheets, pinout diagrams, or application guidance, please contact our engineering support team. They can provide detailed documentation and assistance for your HEF4521BT,653 requirements.

6.How does Aetrix verify that HEF4521BT,653 is sourced from the original manufacturer or authorized distributors?

All HEF4521BT,653 products on Aetrix are procured from qualified distributors and authorized channels. Our dedicated quality assurance team conducts strict verification, including traceability checks and, if necessary, third-party testing. This ensures that HEF4521BT,653 meets industry standards.

7.What is the process for return or replacement of HEF4521BT,653?

All HEF4521BT,653 units undergo pre-shipment inspection (PSI). If there is an issue with HEF4521BT,653, returns or replacements are accepted under the following conditions:

1.Quantity discrepancies, incorrect items, or visible external defects (such as breakage or corrosion), acknowledged by Aetrix.

2.The issue is reported within 90 days of delivery.

3.The HEF4521BT,653 part is unused and in its original packaging.

Return procedure for HEF4521BT,653:

1.Submit a request within 90 days.

2.Obtain a Return Material Authorization (RMA) from Aetrix.

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