Curious to know, Why 32.678 KHz Crystal Oscillator is used in RTC!!

First, let’s understand what is Oscillator and Crystal Oscillator.

Oscillator: An oscillator is a mechanical or electronic device that works on the principles of oscillation: a periodic fluctuation between two things based on changes in energy.
In simple words, Oscillator is a device that produces oscillations.

Classification of Oscillators:

  1. According to the oscillation frequency: high-frequency oscillator, and low
    frequency oscillator.
  2. According to the oscillation waveform: sine wave oscillator, and non-sine wave
  3. According to the oscillation feedback: positive feedback oscillator, and negative
    resistance oscillator.

Examples of Oscillators:

  1. RC Oscillator,
  2. LC Oscillator,
  3. Crystal Oscillator, and etc.,

Crystal Oscillator: A crystal oscillator is an electronic oscillator that makes use of crystal as a frequency-selective element to obtain an inverse piezoelectric effect. It makes use of the mechanical resonance of the vibrating crystal, which has piezoelectric properties, in order to obtain an electric signal with a high-precision frequency. Crystal oscillators are considered superior to ceramic resonators as they have higher stability, higher quality, lower cost, and are smaller in size.

Some examples of Crystal Oscillator:

  1. XO – Crystal Oscillator,
  2. VCXO – Voltage Controlled Crystal Oscillator,
  3. TXCO – Temperature Controlled Crystal Oscillator,
  4. VCTCXO – Voltage Controlled Temperature Compensated Crystal Oscillator,
  5. OCXO – Oven Controlled Crystal Oscillator

Now, What is Hertz(Hz)?

The hertz (symbol: Hz) is the unit of frequency in the International System of Units (SI), equivalent to one event (or cycle) per second. A hertz is an SI-derived unit whose expression in terms of SI base units is s −1, meaning that one hertz is the reciprocal of one second. The hertz is equivalent to one cycle per second.

What is RTC?

A real-time clock (RTC) is an electronic device that keeps track of the current time and date. It is used in many applications such as computers, mobile phones, and appliances. An essential component of an RTC is the clock oscillator, which generates the clock signal that drives the timekeeping mechanism.

One of the main advantages of using a crystal oscillator in an RTC is the stability of the frequency. Quartz crystals have the property of vibrating at a very precise frequency, which is determined by their physical dimensions. This means that the output frequency of a crystal oscillator is highly stable and does not change over time. This stability is crucial for maintaining accurate time in RTCs.

Another advantage of using a crystal oscillator in RTCs is the low power consumption. The oscillator circuit consumes very little power and the crystal itself requires no power to maintain its oscillation. This makes the RTC power efficient, as it can maintain accurate time even when the power is turned off.

Okay!! But, How come 32.678KHz became so famous?

The frequency 32768 Hz (32.768 kHz) is commonly used because it is a power of 2 (2^15) value. And, you can get a precise 1-second period (1 Hz frequency) by using a 15-stage binary counter.

Practically, in the majority of applications, particularly digital, the current consumption has to be as low as possible to preserve battery life. So, this frequency is selected as the best compromise between low frequency and convenient manufacture with market availability and real estate in terms of physical dimensions while designing the board, where low frequency generally means the quartz is physically bigger.

32.678 kHz is commonly used in a variety of electronic applications, including:

  • Real-time clocks (RTCs): The frequency of 32.678 kHz is used in RTCs because it provides a highly stable and accurate time reference. This makes it an ideal choice for applications that require accurate timekeeping, such as computers, mobile phones, and appliances.
  • Microcontrollers: Many microcontrollers use a 32.678 kHz crystal oscillator as their clock source. The crystal oscillator provides a stable and accurate clock signal that is used to control the timing of the microcontroller’s operations.
  • Communication Systems: The frequency of 32.678 kHz is also used in communication systems such as modems and transceivers. The crystal oscillator’s stability and accuracy are crucial for maintaining the integrity of the communication signal.
  • Measurement and Instrumentation: 32.678 kHz frequency is used in measurement and instrumentation devices such as frequency counters, oscilloscopes, and other electronic test equipment.
  • Timing and control: The frequency of 32.678 kHz is used in a variety of timing and control applications such as motor control, power supply control and other industrial control systems.

I hope you enjoyed reading the article as much as I enjoyed writing it.

😁 😁 😁

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