CD4521BM - CMOS 24-Stage Frequency Divider | Texas Instruments
料号： CD4521BM ✗ 停产CD4521BM 概述
A CMOS frequency divider is a type of sequential logic IC that divides an input clock by a fixed binary factor. In the broader semiconductor hierarchy, it belongs to counters and dividers, then logic ICs, and ultimately the wider digital semiconductor category. The CD4521BM is useful when a system needs long division ratios, a generated clock, or a cascaded timing chain without implementing the counter in a microcontroller or discrete flip-flop array. Its oscillator and counter sections provide a dedicated hardware function for timing and sequencing.
The key verified characteristics include a 24-stage ripple-carry counter, 16-pin SOIC packaging, a -55°C to +125°C temperature range, and a 3 V minimum operating voltage as shown in the available cross-reference information. The counter is advanced on the negative transition of IN1, while RESET returns the state to all zeros and disables the oscillator. These characteristics make the device suitable for long-period timers, modulo counters, clock dividers, and low-frequency signal generation. The manufacturer identifies the circuit as a CMOS 24-stage frequency divider in its CD4521B product documentation.
Because the oscillator can be configured with either RC or crystal components, the circuit supports a range of timing approaches. An unused oscillator input must be tied either HIGH or LOW, preventing an undefined input state. RESET provides a deterministic starting condition, and the multiple counter outputs allow different division ratios or timing phases to be observed. This architecture is particularly useful when one input frequency must be converted into several related output frequencies without continuous software intervention.
The CD4521BM is supplied by Texas Instruments in a 16-pin SOIC package. The manufacturer product page provides the CD4521B family data sheet, while distributor records identify the CD4521BM ordering variant, tube packaging, and availability information. Its broad temperature rating supports industrial and instrumentation use, although designers must still verify the complete electrical limits, timing characteristics, and output-drive requirements in the manufacturer data sheet before release.
For oscillator-based designs, calculate the RC or crystal timing network from the manufacturer guidance and keep oscillator traces short and away from noisy switching nodes. For externally clocked designs, ensure that IN1 transitions satisfy the specified negative-edge counting requirement and that unused inputs are tied to defined logic levels. RESET can be used during power sequencing to hold the divider in a known state until the surrounding system is ready.
This product data combines manufacturer-family information, distributor specifications, verified pricing references, cross-reference results, and practical implementation guidance. It also distinguishes genuine same-package substitutes from unspecified or cross-package alternatives so engineers can evaluate replacement decisions without relying on unsupported equivalence claims.
直接替换替代料： CD4521BM ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
CD4521BPW
✅ 直接替换📋 参考替代料（不在目录中）
MC14521BDR2G
✅ 直接替换📋 参考替代料（不在目录中）
MC14521BDG
✅ 直接替换📋 参考替代料（不在目录中）
HEF4521BTD
✅ 直接替换📋 参考替代料（不在目录中）
CD4521BM 最大额定值与电气特性
| Product Type | CMOS 24-stage frequency divider |
| Counter Architecture | 24 ripple-carry binary counter stages |
| Divider Bit Count | 24 bit |
| Logic Family | CD4000 CMOS |
| Counting Edge | Negative transition of IN1 |
| Oscillator Support | RC or crystal oscillator configuration using IN1 |
| Minimum Supply Voltage | 3 V |
| 工作温度范围 | -55°C to +125°C |
| Package Type | 16-pin SOIC |
| Package Dimensions | 0.154 inch width, 3.90 mm |
| Packaging Type | Tube |
| 安装类型 | Surface Mount |
| RoHS 状态 | Compliant |
| Reset Function | Sets all counter outputs to zero and disables the oscillator |
| Lead Time | 3-7 business days |
CD4521BM 0.154 inch width, 3.90 mm 引脚配置指南
CD4521BM（0.154 inch width, 3.90 mm 封装）的引脚配置。 该数字 IC 包含 GPIO、通信接口（UART、SPI、I2C）和电源引脚。请参阅制造商数据手册以了解复用引脚功能和配置选项。对嵌入式系统设计和 PCB 布局至关重要。
暂无详细引脚数据： CD4521BM.
请参阅 数据手册 以查看完整引脚配置。
典型应用
CD4521BM 适用于 6 应用s: Long-Interval Industrial Timers, Precision Clock Divider Networks, RC-Oscillator Timing Modules, Instrumentation Event Counters, Communication Bit-Rate Reduction, Low-Frequency Signal Generation.
Long-Interval Industrial Timers
The CD4521BM is suitable for long-period industrial timing because its 24 ripple-carry counter stages can divide a periodic input into a substantially longer interval. The counter advances on each negative transition of IN1, allowing a stable reference clock to control a much slower event cadence without repeated software counting. Its verified -55°C to +125°C operating range supports demanding temperature environments. RESET can hold the divider at the all-zero state during initialization, and the SOIC package simplifies assembly on conventional surface-mount control boards.
推荐
Precision Clock Divider Networks
The CD4521BM can generate several related clock phases from one periodic input by using the outputs of its 24 ripple-carry stages. This makes it useful in counter, modulo, and clock-distribution networks where reducing frequency is more important than driving a high-speed modern processor clock. A negative-edge counting characteristic provides a defined update behavior, while RESET establishes a known all-zero state. Designers should preserve signal margin at the 3 V minimum supply condition and verify the complete timing limits in the TI data sheet.
推荐
RC-Oscillator Timing Modules
The CD4521BM oscillator section supports RC timing, allowing a compact module to generate and divide a local frequency without requiring an external clock source. The oscillator configuration uses IN1 and can support either RC or crystal implementations according to the TI CD4521B documentation. A HIGH on RESET disables the oscillator and clears the counter, which helps establish repeatable startup behavior. If the oscillator is unused, IN1 must be tied HIGH or LOW so that the input never floats.
推荐
Instrumentation Event Counters
For instrumentation and measurement systems, the CD4521BM can count periodic sensor or timing events and expose divided states for downstream control. Its 24-stage architecture provides a long count chain, while the RESET input permits the system to synchronize measurements to a defined starting point. The -55°C to +125°C range is useful across industrial and laboratory environments, and the 16-pin SOIC package supports compact assembly. Engineers should ensure that event amplitudes satisfy the input thresholds and that timing jitter is acceptable for the intended measurement resolution.
推荐
Communication Bit-Rate Reduction
The CD4521BM can reduce an incoming periodic communication or synchronization signal to a lower internal rate by using its binary counter stages. This application benefits from the dedicated ripple-carry architecture and deterministic negative-edge counting, which avoids dedicating microcontroller instruction cycles to simple division. RESET can inhibit counting until the communication system is ready, and the 16-pin SOIC package is convenient for retrofit boards. The clocking source must have clean transitions and acceptable jitter to prevent stage-to-stage timing errors.
推荐
Low-Frequency Signal Generation
A crystal or RC oscillator connected to the CD4521BM can provide a divided low-frequency output for beacon timing, sampling control, or periodic system actions. The internal 24-stage counter converts the oscillator frequency into a much lower divided rate, while multiple stages can support additional related outputs. RESET supplies a deterministic state for startup and test sequencing. Because oscillator accuracy depends on component tolerance, crystal selection, and layout, engineers should follow the manufacturer guidance and validate frequency stability over the intended temperature range.
推荐
推荐产品汇总
工程参考数据： CD4521BM ——对比、设计指导和合规信息。
选型指南
与替代料对比
| 参数 | 本产品 | CD4521BPW | MC14521BDR2G | MC14521BDG | HEF4521BTD |
|---|---|---|---|---|---|
| Package | 16-pin SOIC | 16-pin SOIC | 16-pin SOIC | 16-pin SOIC | 16-pin SOIC |
| Brand | Texas Instruments | Vishay Intertechnology | onsemi | onsemi | Nexperia |
| Function | CMOS 24-stage frequency divider | 24-stage frequency divider | Frequency divider | Frequency divider | Frequency divider |
| Technology Family | CD4000 CMOS | CD4000 | CMOS | CMOS | CMOS |
| Oscillator and Counter Architecture | Oscillator section plus 24 ripple-carry binary counter stages | Frequency-divider and oscillator function | Frequency-divider function | Frequency-divider function | Frequency-divider function |
关键差异点
- Verified direct-replacement evidence （对比 MC14521BDR2G)
- Original manufacturer family documentation （对比 HEF4521BTD)
- Wide verified temperature rating （对比 CD4521BPW)
- Integrated oscillator and counter architecture （对比 MC14521BDR2G)
设计说明
Do not leave IN1 floating. The verified TI description states that IN1 must be tied either HIGH or LOW when the internal oscillator is not used. RESET must be driven deliberately because a HIGH clears all counter stages and disables the oscillator. Confirm the logic sequence used by the board so that reset assertion does not unintentionally stop an external clock before the system reaches its normal operating state.
For RC or crystal oscillator use, keep the oscillator section physically compact and separate from high-current switching nodes. Follow the manufacturer oscillator guidance for component placement and grounding. The supplied records do not contain the recommended PCB artwork, track lengths, or grounding values, so those details must be obtained from the official data sheet and reference material rather than inferred from the 16-pin SOIC outline.
Design the supply rail for a minimum operating voltage of 3 V while allowing for ripple and transient margin. Because the verified records do not provide the maximum supply voltage, quiescent current, or output-drive limits, the power design cannot be completed from the supplied snippets alone. Review the TI CD4521B data sheet for absolute maximum ratings, recommended operating conditions, and input levels before selecting bypass capacitance or defining the acceptable supply tolerance.
A matching 16-pin SOIC outline does not by itself establish a safe drop-in substitution. Before replacing CD4521BM with CD4521BPW, MC14521BDR2G, MC14521BDG, or HEF4521BTD, compare the numbered pinout, oscillator configuration, reset behavior, counting edge, propagation delays, supply range, output-drive capability, and absolute maximum ratings using each manufacturer’s current data sheet.
合规信息
RoHS compliance is explicitly stated in the verified FindMyChip product information. No verified evidence was supplied for REACH, lead-free status, halogen-free status, conflict-minerals compliance, or automotive qualification.
