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.
HEF4521B: Product Block Diagram
sot109-1_3d
Data Sheets (1)
Application Notes (1)
Brochures (2)
Package Information (1)
Supporting Information (2)
Ordering Information
| Product | Status |
|---|
| HEF4521BT | Active |
Package Information
| Product ID | Package Description | Outline Version | Reflow/Wave Soldering | Packing | Product Status | Part NumberOrdering code(12NC) | Marking | Chemical Content | RoHS / Pb Free / RHF | LeadFree Conversion Date | EFR | IFR(FIT) | MTBF(hour) | MSL | MSL LF |
|---|
| HEF4521BT | | SOT109-1 | SO-SOJ-REFLOW
SO-SOJ-WAVE
SO-SOJ-REFLOW
SO-SOJ-WAVE | Reel 13" Q1/T1 CECC | Active | HEF4521BT,653
(9334 067 70653) | HEF4521BT | HEF4521BT |    | week 4, 2004 | 75.3 | 2.99 | 3.34E8 | 1 | 1 |
| Bulk Pack, CECC | Active | HEF4521BT,652
(9334 067 70652) | HEF4521BT | HEF4521BT | | week 4, 2004 | 75.3 | 2.99 | 3.34E8 | 1 | 1 |
