1.

General description

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) will function as: a crystal oscillator, an input buffer for an

external oscillator or in combination with A1 as an RC oscillator. The crystal oscillator

Each flip-flop divides the frequency of the previous flip-flop by two, consequently the

available for additional flexibility.

also suitable for use over the full industrial (

−40 °C to +85 °C) temperature range.

2.

Features

3.

Applications

4.

Ordering information

HEF4521B

24-stage frequency divider and oscillator

Rev. 05 — 5 November 2009

Product data sheet

Table 1.

Ordering information

All types operate from

−40 °C to +85 °C.

Type number

Package

Name

Description

Version

HEF4521BP

DIP16

plastic dual in-line package; 16-leads (300 mil)

SOT38-4

HEF4521BT

SO16

plastic small outline package; 16 leads; body width 3.9 mm

SOT109-1