CD4521 24-Stage Frequency Divider

The CD4521 is a 24-stage frequency divider from the 40xx-series CMOS family, designed for long-duration timing and very low-frequency clock generation. The 24-stage binary counter provides division ratios up to 2^24 (16,777,216), enabling extremely low output frequencies from relatively high input clock sources. This makes the device suitable for real-time clocks, periodic interrupt generation, and ultra-long delay circuits.

Operating from 3V to 18V, the CD4521 includes a built-in oscillator that can be controlled by an external RC network or crystal, or an external clock can be applied directly. The device provides multiple tap outputs from various stages, allowing selection of different division ratios without additional counters. A master reset input clears the counter and initiates a new timing cycle.

1. 24-stage frequency divider with 2^24 division capability
2. Multiple tap outputs for selectable division ratios
3. Built-in oscillator with external RC control
4. Master reset for counter initialization
5. Wide supply voltage: 3V to 18V DC
6. Extremely low power consumption for battery operation
7. Standard 16-pin DIP package
8. Ideal for long-duration timing and low-frequency generation