HEF4521BT: 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.

HEF4521BT: Product Block Diagram
sot109-1_3d
Data Sheets (1)
Name/DescriptionModified Date
24-stage frequency divider and oscillator (REV 7.0) PDF (199.0 kB) HEF4521B [English]30 Mar 2016
Application Notes (1)
Name/DescriptionModified Date
Pin FMEA HEF4000 family (REV 2.0) PDF (30.0 kB) AN11051 [English]21 Aug 2015
Brochures (2)
Name/DescriptionModified Date
電圧レベルシフタ (REV 1.1) PDF (3.1 MB) 75017511_JP [English]16 Feb 2015
Voltage translation: How to manage mixed-voltage designs with NXP® level translators (REV 1.0) PDF (2.6 MB) 75017511 [English]20 May 2014
Package Information (1)
Name/DescriptionModified Date
plastic small outline package; 16 leads; body width 3.9 mm (REV 1.0) PDF (192.0 kB) SOT109-1 [English]08 Feb 2016
Supporting Information (2)
Name/DescriptionModified Date
Footprint for reflow soldering (REV 1.0) PDF (9.0 kB) SO-SOJ-REFLOW [English]08 Oct 2009
Footprint for wave soldering (REV 1.0) PDF (8.0 kB) SO-SOJ-WAVE [English]08 Oct 2009
Ordering Information
ProductStatusFamilyVCC (V)FunctionOutput drive capability (mA)DescriptionLogic switching levelsPackage versiontpd (ns)Power dissipation considerationsTamb (Cel)Rth(j-a) (K/W)Ψth(j-top) (K/W)Rth(j-c) (K/W)Package nameNo of pins
HEF4521BTActiveHEF4000B4.5-15.5 VBinary counters/timers+/- 2.424-stage frequency divider and oscillatorCMOSSOT109-1220medium-40~85651.022.8SO1616
Package Information
Product IDPackage DescriptionOutline VersionReflow/Wave SolderingPackingProduct StatusPart NumberOrdering code(12NC)MarkingChemical ContentRoHS / Pb Free / RHFLeadFree Conversion DateEFRIFR(FIT)MTBF(hour)MSLMSL LF
HEF4521BTSOT109-1SO-SOJ-REFLOW SO-SOJ-WAVE
SO-SOJ-REFLOW SO-SOJ-WAVE
Reel 13" Q1/T1 CECCActiveHEF4521BT,653 (9334 067 70653)HEF4521BTHEF4521BTweek 4, 200475.32.993.34E811
Bulk Pack, CECCActiveHEF4521BT,652 (9334 067 70652)HEF4521BTHEF4521BTweek 4, 200475.32.993.34E811
24-stage frequency divider and oscillator HEF4521BT
Pin FMEA HEF4000 family HEF4894B_Q100
電圧レベルシフタ 74AVC16245DGG-Q100
Voltage translation: How to manage mixed-voltage designs with NXP® level translators 74AVC16245DGG-Q100
plastic small outline package; 16 leads; body width 3.9 mm NPIC6C596A_Q100
Footprint for reflow soldering NPIC6C596A_Q100
Footprint for wave soldering NPIC6C596A_Q100
HEF4521B
SA614A