Recommended crystal oscillator solutions commonly used in bone conduction headphones

Did you know that snakes living in the ocean receive the vibrations of sound in the water through their lower bones and transmit them to their ears? After Beethoven lost his hearing, he bit the baton with his teeth and placed his head on the piano, so that the sound of the piano could be transmitted to his ears through the baton, and he continued to compose.

In fact, we often unconsciously experience another mysterious transmission channel of sound - bone conduction. Cover your ears with your hands and talk to yourself no matter how quiet the sound is, we can hear what we say, this is the result of bone conduction.

Bone Conduction Encyclopedia

Bone conduction is a method of sound conduction, which converts sound into mechanical vibrations of different frequencies and transmits sound waves through the human skull, bony labyrinth, inner ear lymph, spiral organ, auditory nerve, and auditory center.

Compared with the classic sound conduction method that generates sound waves through a diaphragm, bone conduction eliminates many steps in sound wave transmission and can achieve clear sound restoration in a noisy environment. The sound waves will not affect others due to diffusion in the air. Whether it is a sports scene or a daily use scene, it can be easily controlled, thus creating a more comfortable and safe listening experience.

Bone conduction headphones

Bone conduction headphones can meet the needs of different groups of people and different scenarios. For example, hearing aids can transmit auditory signals directly to the inner ear through the vibration of the temporal bone, causing inner ear hearing. Normal hearing includes bone conduction and air conduction. Of course, air conduction is usually the main one. When there is a problem with the air conduction pathway, such as stenosis or closure of the ear canal, there is no way to use airway headphones, and bone conduction headphones can be used instead.

For example, in special scenarios, loud speaking is not allowed, and the loss rate of sound in bone conduction is much lower than that in air conduction. Bone conduction microphone technology headphones mainly use throat bone conduction. Due to the short distance and low loss, only a small sound is needed to accurately convey the information you want to express.

Crystal Oscillator Solutions

Bone conduction headphones have high requirements for sound quality and noise reduction. The crystal oscillator provides a stable working clock pulse frequency, which is the key to affecting noise. Therefore, it is very important to choose a stable and reliable crystal oscillator. The crystal oscillator used in bone sensor headphones should meet the following conditions:

High stability: The frequency accuracy on the board should be ±10PPM to obtain better radio reception and make it more stable and reliable;

Low power consumption: In deep sleep mode, the crystal oscillation remains unchanged, but at a lower drive strength to reduce power consumption;

Shockproof: The operating temperature range is -40℃~+85℃, with good stability and shockproof performance;

Miniaturization: Common bone conduction headphones are generally smaller in size, making them more comfortable to wear.

YXC crystal oscillator recommendation

So, in the limited space of the circuit board, Yangxing recommends the size of 2016 and 1612 SMD crystal oscillators, which have the characteristics of miniaturization, high precision, low power consumption and low aging; common frequencies are: 16MHZ, 24MHZ, 24.576MHZ, 26MHZ, 32MHZ, 40MHZ;

YSX211SL/YSX1612SL product parameters and advantages are as follows:

(1) It has miniaturization and high precision, meeting the current hot smart wearable market;

(2) High stability, the total temperature difference reaches ±20PPM, the frequency deviation at normal temperature is ±10ppm, the higher the accuracy, the more stable it is;

(3) Comply with RoHS standards, green and environmentally friendly, and cost-effective;

(4) SMD metal packaging has excellent environmental resistance and is conducive to reducing electromagnetic interference effects;

(5) Better temperature performance, reaching industrial grade temperature.

If there are too many stray signals on the circuit board, there is a concern that the frequency stability of the passive crystal oscillator will be disturbed irregularly to varying degrees. In order to avoid causing disorder in the electronic product system, it is recommended to choose an active crystal oscillator: YSO110TR series.

YSO110TR product parameters and advantages are as follows:

(1) Compatible with a variety of voltages from 1.8V to 3.3V, with three-state output TTL/HCOMS compatibility;

(2) Small, ultra-thin quartz crystal oscillator, with a minimum package size of 1.6*1.2*0.6mm;

(3) It has stable oscillation characteristics under extreme environmental conditions and oscillates within 3ms;

(4) High stability, total temperature difference reaches ±20PPM, shock and vibration resistance, high reliability;

(5) Industrial-grade temperature: -40℃~+85℃. It can still work stably and continuously in special environments, and is not prone to "temperature drift", thus not affecting the normal operation of the energy storage equipment.