CD4020BD - 14-Stage CMOS Counter | Texas Instruments
料号： CD4020BD ✓ 量产中CD4020BD 概述
A binary counter is a sequential digital-logic component that advances its internal count when triggered by a clock edge. The CD4020 belongs to the CMOS counter/divider hierarchy, where it combines a clocked counting circuit with multiple parallel output stages. Each output represents a different binary bit of the accumulated count, allowing one incoming clock waveform to produce division ratios from 2 through 16,384.
The principal features of the CD4020BD include 14 ripple-carry stages, operation across a 3 V to 18 V supply range, and operation up to 24 MHz. Its parallel outputs support Q0 through Q12 and the final divided output Q14. A master reset terminal returns the counting sequence to its initial state, while separate oscillator terminals provide access to the internal oscillator or allow external timing signals to drive the counter.
Ripple-carry implementation means that each counting stage triggers the next stage after a propagation delay. This architecture is effective when the outputs are sampled at a slower rate than the input clock, but it is not a synchronous design in which all stages update on one common edge. Engineers should therefore account for accumulated propagation delay and use the device where output timing does not require simultaneous state changes.
Typical uses include digital frequency dividers, periodic-event generators, timer and delay circuits, industrial counters, instrumentation, and embedded control logic. The CD4020 can generate divide-by-2, divide-by-4, divide-by-8, divide-by-16, and higher ratios without requiring a bank of individual flip-flops. Its broad supply range also permits operation across common 3.3 V, 5 V, and higher-voltage CMOS systems.
When designing a divider, verify the maximum clock rate against supply voltage and temperature, and place a suitable bypass capacitor close to the supply terminals. Do not drive unused inputs with floating nets. Because ripple transitions can occur between stages, add qualification at each output when downstream circuitry must not observe intermediate count values.
This product page combines the manufacturer device information, sourcing guidance, complete package pin assignment, operating comparisons, and practical design guidance for engineers evaluating the CD4020BD as a legacy-compatible CMOS counter and divider.
直接替换替代料： CD4020BD ——相同封装，引脚兼容。需要 PCB 改动的不同封装料号已排除。
该产品暂无直接替换替代料。
请求替代料CD4020BD 最大额定值与电气特性
| Counter Type | 14-stage ripple-carry binary counter/divider |
| 工作电源电压 | 3 V to 18 V |
| 最大时钟频率 | 24 MHz |
| Counting Stage Count | 14 stages |
| Maximum Binary Divide Ratio | 16,384 |
| Output Count | Q0 through Q12 and Q14 |
| Logic Family | CMOS |
| 封装 | 16-pin SOIC |
| 安装类型 | Surface mount |
| Clock Edge | Negative edge |
| Reset Type | Master reset |
| Oscillator Inputs | 2 oscillator terminals |
| RoHS 状态 | Compliant |
CD4020BD 引脚配置
| 引脚 1 | CLK — Negative-edge-triggered clock input |
| 引脚 2 | CLK0 — Oscillator or clock input 0 |
| 引脚 3 | Q0 — First binary counter output |
| 引脚 4 | Q1 — Second binary counter output |
| 引脚 5 | Q2 — Third binary counter output |
| 引脚 6 | Q3 — Fourth binary counter output |
| 引脚 7 | VSS — Ground reference |
| 引脚 8 | MR — Master reset input |
| 引脚 9 | Q10 — Binary counter output |
| 引脚 10 | Q8 — Binary counter output |
| 引脚 11 | Q9 — Binary counter output |
| 引脚 12 | Q11 — Binary counter output |
| 引脚 13 | Q12 — Binary counter output |
| 引脚 14 | OSC1 — Oscillator input 1 |
| 引脚 15 | OSC0 — Oscillator input 0 |
| 引脚 16 | VDD — Positive supply voltage |
典型应用
CD4020BD 适用于 6 应用s: Digital Frequency Divider, Periodic Event Generator, Industrial Timer Control, Instrumentation Signal Conditioning, Embedded Control Timing, Test and Measurement Clocking.
Digital Frequency Divider
The CD4020BD fits frequency-divider designs because it counts on a negative clock edge and exposes a separate output for each of 14 binary count stages. A 24 MHz maximum clock capability allows moderate-frequency inputs to be reduced into lower timing or control rates, although the actual operating limit must be checked against supply voltage and temperature. Select Q0 for division by 2 or progressively higher outputs for larger ratios. Because ripple transitions do not occur simultaneously, qualify the selected output before it drives sensitive logic. Use a short clock route, a local supply bypass capacitor, and a definite ground reference to prevent counting errors.
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Periodic Event Generator
The CD4020BD can create a periodic enable pulse or delayed event by dividing a continuous oscillator signal and decoding selected counter stages. Its 14-stage architecture supports binary divide ratios beyond the eight stages commonly needed for simple waveform division, while Q14 supports division by 16,384. The device is especially useful when a system needs a long interval without adding a large chain of individual flip-flops. Ensure that the oscillator amplitude and frequency meet the CD4020B input requirements, and decode more than one output if the desired active interval must avoid intermediate ripple states.
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Industrial Timer Control
The CD4020BD is appropriate for repeatable industrial timing and control sequences because its counter outputs provide selectable delay stages without a microcontroller timing loop. A stable oscillator or system clock can establish the time base, while the counter stage selects the required delay. The 3 V to 18 V operating range supports multiple legacy industrial control voltages, subject to the input and output limits in the Texas Instruments datasheet. Keep long signal paths away from the clock and reset nets, provide adequate bypassing, and qualify outputs that trigger relays or safety-related equipment.
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Instrumentation Signal Conditioning
The CD4020BD can serve as a clock divider or event-counting element in instrumentation that reduces a fast reference signal to a measurable or processable rate. Multiple available outputs make it possible to select a useful fundamental or a higher-ratio signal without redesigning the timing chain. Its CMOS implementation is appropriate for low-power logic systems, but the selected output must remain within the load-current and voltage limits specified for the operating condition. Use a clean reference clock, minimize loading on counter outputs, and add a latch when the acquisition system must sample a stable binary value.
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Embedded Control Timing
The CD4020BD can offload repetitive counting or periodic-enable generation in an embedded control design, reducing dependence on microcontroller timer resources. A system clock or oscillator output can feed the counter, while one of Q0 through Q12 or Q14 supplies a divided timing reference. The device is useful when the required ratio is fixed and the acceptable ripple behavior is understood. The interface should remain compatible with the host logic's voltage levels, and an external synchronization stage may be needed if the host samples the divider asynchronously. Resetting the counter from a defined controller signal helps establish repeatable acquisition windows.
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Test and Measurement Clocking
The CD4020BD is useful in test and measurement systems that need a divided clock, delayed trigger, or repetitive strobe derived from a common oscillator. Its 14 stages allow a compact binary ratio selection, while the maximum clock frequency supports faster reference signals than conventional low-speed timer parts. Keep the output path short and provide a ground plane that supports predictable switching behavior. If the instrument measures timing directly at a ripple output, account for propagation delay through the selected number of stages. A downstream flip-flop or latch can create a clean edge for precision triggering.
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推荐产品汇总
工程参考数据： CD4020BD ——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 |
|---|---|
| Package | 16-pin SOIC |
| Brand | Texas Instruments |
| Counter Architecture | 14-stage ripple-carry binary counter/divider |
| Operating Supply Voltage | 3 V to 18 V |
| Maximum Clock Frequency | 24 MHz |
| Maximum Divide Ratio | 16,384 |
| Counting Edge | Negative edge |
| Reset Function | Master reset |
| Logic Family | CMOS |
关键差异点
- Fourteen counting stages provide a broad binary division range （对比 HEF4020BP)
- High-speed CMOS operation for clock-divider designs （对比 HEF4020BP)
- Single-package counter and oscillator access （对比 CD4060BK)
设计说明
Place a high-frequency bypass capacitor as close as practical to VDD pin 16 and VSS pin 7, with a short ground return. This is especially important because counter transitions can produce current pulses on the supply rails. Do not infer the capacitor value from generic guidance; consult the manufacturer datasheet's decoupling recommendations and the actual clock rate before finalizing the network.
Treat Q0 through Q14 as ripple outputs whose transitions can propagate through multiple stages at different times. If downstream circuitry interprets one output as a synchronized binary word, capture it with a latch after allowing the required settling interval. This prevents an intermediate count from being sampled during the rollover sequence.
Keep the CLK route short and away from output and reset nets to reduce clock feedthrough and false transitions. Use a continuous ground plane where practical and avoid routing the oscillator or master-reset signal beneath noisy digital routes. Confirm every unused input is connected to a defined logic level because a floating CMOS input can produce unpredictable switching.
Do not assume that the highest nominal clock frequency applies at every supply voltage, temperature, or output-loading condition. Check the manufacturer timing tables, output drive current, and propagation-delay limits for the operating corner. Likewise, do not approve a replacement based only on the phrase '14-stage counter'; verify package dimensions, pin functions, reset polarity, and output timing.
合规信息
RoHS compliance is identified in the CD4020BD component summary. Other compliance fields require confirmation from the manufacturer or current supplier documentation.