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Why rtc use 32.768khz?

3 Answer(s) Available
Answer # 1 #

The 32.768kHz quartz resonator (quartz crystal) is the most commonly used basic frequency component (Tuning Fork Quartz Crystal), and watches, mobile phones, computers, outdoor LED displays, and clocks displayed on billboards in daily life are evolved from it . 32768Hz is a very important standard frequency, because 32768 is equal to the 15th power of 2, and 32768Hz can be divided by 15 times to obtain a time signal of 1 second.

The 32.768kHz resonator is mainly used in real-time clock applications and is also the signal source for the low-speed external clock (LSE) of the MCU. The typical parameters of 32.768kHz quartz crystal commonly used in MCU clock source are as follows:

It should be noted that when an external crystal is used as the clock source, if the input and output of adjacent pins of the MCU are high-frequency pulses, it will interfere with the 32.768kHz signal and cause jitter, which will affect the timing and cause timing deviation. Therefore, the adjacent pin of the external crystal oscillator should not be used as the input and output port of the high-frequency signal.

32.768kHz crystal oscillators are precision frequency devices, which are assembled from a 32.768kHz crystal and a CMOS oscillating circuit. Therefore, there is no need to connect any additional components when using it. Typical applications include general-purpose clock generators for digital systems, clock drivers for RTCs, clock retention for network servers and computers, mobile phones, field communication equipment, and water, electricity, and three-meter applications.

The typical performance and requirements of commonly used 32.768kHz oscillators are as follows:

The RTC module is a product that integrates a 32.768kHz crystal oscillator and a real-time clock chip. It has an oscillation circuit, clock function, calendar function and alarm function. In order to obtain a more accurate time, the module should use a high-precision frequency oscillator (quartz wafer) and a chip for controlling components, and pay attention to the best match between the crystal oscillator and the RTC chip.

The RTC module is oriented to specific applications, requiring high precision, high stability, and low power consumption. It supports the I2C bus and provides functions such as calendar information, alarm clock, and timer. Due to the poor temperature characteristics of ordinary tuning fork crystals (Tuning Fork Quartz Crystal), some RTC modules for financial, electric power, communication and other applications use TCXO to improve frequency accuracy. For example, the characteristic parameters of Epson RX-4803LC are as follows:

1/100-Second Timer Control Register

The RTC module provides a high-performance and simple solution for building a high-precision synchronous time processing system. The main applications include various clocks and watches, financial systems, power meters, security systems, and road toll systems. Since there is no need to adjust the frequency, the user's design efficiency, product quality and time to market are improved.

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Siddhesh Brabant
Answer # 2 #

There are many reasons this is the preferred frequency of engineers including: Divides to 1 kHz – 32.768 kHz crystals are easier to calculate clock signals with since they divide down to 1kHz, which is equivalent to one second in frequency.

Griffith bctlxped Lekhwar
Answer # 3 #

A piezoelectric crystal that vibrates mechanically to produce an electrical signal with a precise frequency is known as a Crystal Oscillator, an electronic oscillator circuit. It also includes an automated amplitude control system, and the frequency drift caused by temperature changes is relatively small. Only high-frequency applications can benefit from using crystal oscillators.

Every microcontroller needs a crystal oscillator; in choosing one, try to get silicon oscillators if the accuracy is sufficient and the cost is also reasonable; otherwise, use quartz crystal. One particular clock crystal frequency for timing devices, a 32.768 kHz crystal oscillator, is primarily utilized in compact communication devices. Both SMD/SMT type crystal resonators and DIP 2 pin through hole tuning forks are supported by YXC.

You may rely on the 32.768 kHz oscillators from ChipSun, all of which come with a CMOS-compatible output signal if you don’t want to put in the work of constructing the ideal circuit for your tuning fork crystal. This rail-to-rail output makes it possible to connect to all popular microcontrollers and RTC devices exceptionally quickly and easily.

For instance, it’s quite simple to utilize the 32.768 kHz crystal oscillator. A relatively low current consumption distinguishes it since it contains a tuning fork crystal. Additionally, it may be used in applications that require a changeable operating voltage between 1.5V and 5.0V, which makes it especially appropriate for battery-powered ones. The operating temperature significantly influences its output frequency due to the usage of a tuning fork crystal.

The benefit of an oscillator over a tuning fork crystal is not limited to its simplicity of use. The usage of the ChipSun-oscillators 32.768 kHz is supported by the association between the output frequency and operating temperature indicated above. Because these oscillators don’t employ tuning fork crystals but rather an “AT-cut” quartz blank, the operating temperature has far less impact on the output frequency.

Even more, stable frequency performance is provided. It is a 32.768 kHz TCXO with unrivaled frequency stability of up to +/- 5 ppm throughout a hotness range of -40°C to +85°C.

Precision heat correction, carried out at various temperatures during manufacturing, results in exceptional frequency stability. This 32.768 kHz crystal oscillator is highly resistant to changes in operating voltage thanks to the manufacturing “trimming” process.

Although it is simple to create low-power digital functions, oscillators are analog devices. It is exceedingly challenging to achieve both great precision and minimal power at the same time. Epson’s TG-3541CE achieves significantly higher accuracy and lower power, 0.6 A, than competing solutions by utilizing a special low-ESR kHz crystal co-packaged with a DTCXO oscillator and manufactured using low-leakage transistor technology. This makes it the most accurate and low-power 32.768 kHz oscillator on the market.

ChipSun, a recognized leader in the development, uses its core technology and distinctive strengths to develop quartz crystal oscillators. Its products conform to environmental protection laws such as RoHS, REACH, and others. In the smallest packaging available in the market, they create a tiny crystal unit and oscillation circuit. A compact crystal oscillator. Utilizing an oscillator tuning-fork quartz, which is incredibly adaptable, may be employed in a range of electronic systems to assist minimize both system size and current consumption.

In addition to conserving vital board space, the quartz and oscillator are combined into a single device, which addresses issues with a frequency accuracy and quality. Before shipment, the characteristics of the crystal oscillator are guaranteed, assuring quality and reliability and streamlining design, sourcing, and manufacturing.

The operation of an electrical or mechanical device known as an oscillator is based on the oscillation idea, which describes a regular alternation between two particles based on fluctuations in energy. Metal detectors, clocks, radios, computers, and other gadgets all employ oscillators.

The function of a kHz oscillator is to generate a signal at a specific frequency. This oscillator has many uses outside of radio communications, audio equipment, and scientific instrumentation. KHz oscillators are a specific type of electrical oscillator that can create signals with an exact frequency.

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