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) 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

HEF4521B属于集成电路（IC） > 计数器，除法器。安世半导体(中国)有限公司制造生产的HEF4521B计数器，除法器计数器和除法器 IC 是数字逻辑器件，可对输入发生的逻辑转换进行计数，然后使用多个并行输出重新发送累加的计数，和/或生成单个输出信号转换，从而对应用某些整数数量输入信号转换进行响应。除了简单的事件计数，它们还可用于各种频率合成应用。