CMOS Counter Circuit

Product Specifications

Technical details and manufacturing context for CMOS Counter Circuit

Definition

A CMOS counter circuit is a fundamental component within a Real-Time Clock (RTC) system. It is responsible for counting precise clock pulses generated by a crystal oscillator. This count is used to increment time registers (seconds, minutes, hours) and maintain accurate timekeeping, even when the main system power is off, by utilizing a backup power source. The circuit operates by using a series of CMOS flip-flops connected in a cascaded configuration (e.g., ripple counter, synchronous counter). Each flip-flop toggles its state based on the incoming clock pulse from the RTC's oscillator. The binary output of these flip-flops represents the count value. Control logic manages overflow (e.g., resetting after 60 seconds) and interfaces with other RTC components like registers and the I2C/SPI communication bus. The circuit is fabricated on a silicon semiconductor wafer, with silicon dioxide as an insulator and metal interconnects (typically aluminum or copper). Key parameters include a supply voltage range of 3–18 V DC, operating temperature from -40 to 85 °C (per IEC 60747), maximum clock frequency of 10–50 MHz, propagation delay of 10–200 ns (at VDD=5V, CL=50pF), input high voltage of 0.7×VDD–VDD, input low voltage of 0–0.3×VDD, output high voltage of VDD–0.5–VDD (at IOH=-0.5mA), output low voltage of 0–0.5 V (at IOL=0.5mA), quiescent current of 0.1–5 µA (at VDD=5V, no load), power dissipation of 0.5–2 mW (at 1 MHz, VDD=5V), and ESD tolerance of 2000–4000 V (human body model, per IEC 61340-3-1). Package types include DIP-14 to DIP-16 (per JEDEC MS-001), with SOIC also available. These values are directory reference ranges and must be confirmed for the specific model and application. Always verify model-specific specifications and standards with the legal manufacturer or supplier.

Working Principle

The CMOS counter circuit uses cascaded flip-flops to count clock pulses. Each flip-flop toggles on the clock edge, producing a binary count. Control logic resets the count at overflow (e.g., after 60 seconds) and interfaces with RTC registers and communication buses. The circuit operates within specified voltage and temperature ranges, and its performance depends on supply voltage and load.

Common Materials

Silicon (Semiconductor Wafer), Silicon Dioxide (Insulator), Metal (Interconnects - typically Aluminum or Copper)

Technical Parameters

Parameter	Typical range	Notes & selection driver
Supply Voltage	3–18 V DC	Operating range for CMOS devices
Operating Temperature	-40–85 °C	Junction temperature limitsIEC 60747
Maximum Clock Frequency	10–50 MHz	Depends on supply voltage and load
Propagation Delay	10–200 ns	At VDD=5V, CL=50pF
Input High Voltage	0.7×VDD–VDD V	Minimum high-level input voltageIEC 60747
Input Low Voltage	0–0.3×VDD V	Maximum low-level input voltageIEC 60747
Output High Voltage	VDD–0.5–VDD V	At IOH=-0.5mA
Output Low Voltage	0–0.5 V	At IOL=0.5mA
Quiescent Current	0.1–5 µA	At VDD=5V, no load
Package Type	DIP-14–DIP-16	Also available in SOICJEDEC MS-001
Power Dissipation	0.5–2 mW	At 1 MHz, VDD=5V
ESD Tolerance	2000–4000 V	Human body modelIEC 61340-3-1

Ranges are indicative industry figures for RFQ preparation, not a supplier commitment. Confirm every value and standard with the legal manufacturer before ordering.

Components / BOM

CMOS Flip-Flops Part
Basic memory element that stores one bit of the count; toggles state on clock edge.

Material: Silicon-based semiconductor
Clock Input Buffer Part
Conditions the clock signal from the oscillator for reliable triggering of the flip-flops.

Material: Silicon-based semiconductor
Output Registers/Buffers Part
Hold and drive the counted binary value for reading by the RTC's control logic or external microcontroller.

Material: Silicon-based semiconductor with metal interconnects
Control Logic
Resets the count at overflow and hands the value to the RTC registers and bus.

Applied To / Applications

This component is essential for the following industrial systems and equipment:

Real-Time Clock

View system integration details

Manufacturers of CMOS Counter Circuit

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Compiled and source-reviewed by the CNFX editorial team. Each manufacturer above links to the page on that company's own website where the product is listed, with the date we checked it. How we source and review · Page last updated 6 September 2026

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Frequently Asked Questions

What is the typical supply voltage range for a CMOS counter circuit?

The typical supply voltage range is 3–18 V DC, as listed in the directory. However, you must verify the exact range for the specific model with the manufacturer.

How does the CMOS counter circuit maintain time when the main power is off?

It uses a backup power source to continue counting clock pulses from the crystal oscillator, allowing time registers to increment and maintain accurate timekeeping.

What is the maximum clock frequency for this circuit?

The directory lists a maximum clock frequency of 10–50 MHz, depending on supply voltage and load. Confirm the actual value for your application with the supplier.

Which standards apply to the operating temperature and ESD tolerance?

The operating temperature range (-40 to 85 °C) references IEC 60747, and ESD tolerance (2000–4000 V) references IEC 61340-3-1. These are verification references; compliance must be confirmed with the manufacturer.

Data Basis

Editorial classification, named public sources where available, and source-reviewed manufacturer records.

Preliminary Technical Classification

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voltage:	3V to 18V supply range (typical CMOS operating voltage)
frequency:	Up to 50 MHz maximum clock frequency (depends on specific model)
temperature:	-40°C to +85°C (industrial grade), -55°C to +125°C (military grade)
power consumption:	Low static power (nanoamps), dynamic power depends on frequency and load

Product Specifications

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