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HEF4521B

24-stage frequency divider and oscillator

The HEF4521B consists of a chain of 24 toggle flip-flops with an overriding asynchronous master reset input (MR), and an input circuit that allows three modes of operation. The single inverting stage (A2 to Y2) functions as: a crystal oscillator, an input buffer for an external oscillator or in combination with A1 as an RC oscillator. The crystal oscillator operates in Low-power mode when pins VSS1 and VDD1 are supplied via external resistors.

Each flip-flop divides the frequency of the previous flip-flop by two, consequently the HEF4521B counts up to 224 = 16777216. The counting advances on the HIGH-to-LOW transition of the clock (A2). The outputs from each of the last seven stages (218 to 224) are available for additional flexibility.

It operates over a recommended VDD power supply range of 3 V to 15 V referenced to VSS (usually ground). Unused inputs must be connected to VDD, VSS, or another input.

Features and benefits

  • Wide supply voltage range from 3.0 V to 15.0 V

  • CMOS low power dissipation

  • High noise immunity

  • Low power crystal oscillator operation

  • Fully static operation

  • 5 V, 10 V, and 15 V parametric ratings

  • Standardized symmetrical output characteristics

  • Complies with JEDEC standard JESD 13-B

  • ESD protection:

    • HBM JESD22-A114F exceeds 2000 V

    • MM JESD22-A115-A exceeds 200 V

  • Specified from -40 °C to +85 °C

Parametrics

Type numberProduct statusVCC (V)Output drive capability (mA)Logic switching levelstpd (ns)Power dissipation considerationsTamb (°C)Rth(j-a) (K/W)Ψth(j-top) (K/W)Rth(j-c) (K/W)Package name
HEF4521BTProduction3.0 - 15± 2.4CMOS220medium-40~85651.022.8SO16

Package

Type numberPackagePackage informationReflow-/Wave solderingPackingStatusMarkingOrderable part number, (Ordering code (12NC))
HEF4521BT
SO16
(SOT109-1) 		SOT109-1SO-SOJ-REFLOW
SO-SOJ-WAVE
SOT109-1_653ActiveHEF4521BTHEF4521BT,653
( 9334 067 70653 )

The variants in the table below are discontinued. See the table Discontinuation information for more information.

Type numberPackagePackage informationReflow-/Wave solderingPackingStatusMarkingOrderable part number, (Ordering code (12NC))
HEF4521BT
SO16
(SOT109-1) 		SOT109-1SO-SOJ-REFLOW
SO-SOJ-WAVE
SOT109-1_652Withdrawn / End-of-lifeHEF4521BTHEF4521BT,652
( 9334 067 70652 )

Discontinuation information

Type numberOrderable part number, (Ordering code (12NC))Last time buy dateLast time delivery dateReplacement productStatusComments
HEF4521BT9334067706522021-12-312022-06-30HEF4521BT

    Environmental information

    Type numberOrderable part numberChemical contentRoHSRHF-indicatorLeadfree conversion date
    HEF4521BTHEF4521BT,653HEF4521BTweek 4, 2004

    The variants in the table below are discontinued. See the table Discontinuation information for more information.

    Type numberOrderable part numberChemical contentRoHSRHF-indicatorLeadfree conversion date
    HEF4521BTHEF4521BT,652HEF4521BTweek 4, 2004
    Quality and reliability disclaimer

    Documentation (7)

    File nameTitleTypeDate
    HEF4521B24-stage frequency divider and oscillatorData sheet2023-10-19
    AN11051Pin FMEA HEF4000 familyApplication note2019-01-09
    Nexperia_Selection_guide_2023Nexperia Selection Guide 2023Selection guide2023-05-10
    SO-SOJ-WAVEFootprint for wave solderingWave soldering2009-10-08
    SO-SOJ-REFLOWFootprint for reflow solderingReflow soldering2009-10-08
    WAVE_BG-BD-1Wave soldering profileWave soldering2021-09-08
    SOT109-1plastic, small outline package; 16 leads; 1.27 mm pitch; 9.9 mm x 3.9 mm x 1.75 mm bodyPackage information2023-11-07

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