Advanced MLCC Solutions for Noise Reduction in Laptop Computer Battery Lines

2024-01-16

Are you seeking advanced solutions to suppress acoustic noise in the battery lines of your laptop computers? Look no further! We are delighted to introduce our state-of-the-art Multilayer Ceramic Capacitors (MLCC) designed specifically for noise reduction in laptop battery lines.

At Hongda Capacitors, we understand the significance of providing a peaceful and efficient user experience. Our MLCC solutions are meticulously engineered to effectively suppress unwanted acoustic noise, ensuring a harmonious working environment while maximizing the performance and lifespan of your laptop computers.

Key Benefits of our MLCC Solutions:

1. Enhanced noise reduction: Our MLCC capacitors are designed to mitigate acoustic noise, minimizing disturbances caused by battery line operations.

2. Reliable performance: Our high-quality MLCC solutions provide excellent noise suppression capabilities, allowing for stable and reliable laptop computer operation.

3. Extended battery life: By reducing noise in the battery lines, our MLCC capacitors help optimize power delivery and minimize energy loss, resulting in extended battery life for uninterrupted usage.

4. Easy integration: Our MLCC solutions are designed to seamlessly integrate into existing laptop computer architectures, ensuring hassle-free implementation without compromising on performance.

Let me introduce the details by below 7 factors:

1. Introduction 

In the past, tantalum and aluminum electrolytic capacitors were commonly used in electronic devices, but in recent years they have been replaced with ceramic capacitors due to product miniaturization, reliability problems, etc.

With the shift toward multifunctionality and silencing in electronic devices, previously unnoticed "acoustic noise (sound)" caused by ceramic capacitors is becoming one major design issue in laptop PCs, smartphones (mobile phones), car navigation systems, wireless charging, and other power supply circuits.

In laptop PCs, "acoustic noise (sound)" caused by ceramic capacitors used in battery lines sometimes becomes a problem.

Because the internal operation of the laptop PC changes when the operation mode is changed from a sleep state/standby screen or other mode, the magnitude of the "acoustic noise (sound)" changes according to the operation mode, and the acoustic noise is also heard differently.

This document introduces measures to address "acoustic noise (sound)" due to capacitors in laptop PC battery lines, a method of evaluating acoustic noise, and the mechanism by which such noise occurs.

2. Capacitors that are prone to causing "acoustic noise (sound)" in laptop PCs 

Large numbers of capacitors are used in the battery line (DC-DC converter primary side) of a laptop computer, and the use of ceramic capacitors in this battery line may produce acoustic noise.

Capacitors that are generally prone to causing "acoustic noise (sound)"

50. Capacitors with a large size
50. Capacitors with a large capacitance
50. Capacitors with a large line voltage, voltage fluctuation (current fluctuation)
50. Multiple ceramic capacitors with the characteristics described above are equipped on the same line.

Reasons why capacitors in the battery lines of laptop PCs are prone to causing "acoustic noise"

50. High battery line voltage at 10 to 20V
50. Voltage fluctuations easily occur in order to provide power to the CPU, camera, RF modules, and other circuits.
50. With large component sizes/capacitance, the dielectric expansion/contraction due to the voltage application increases.

3. Example of an anti-noise effect 

This is an example of the anti-noise effect for the sleep state/standby screen, which are operation modes that are prone to acoustic noise or have a high sound pressure level in laptop PCs.

When ceramic capacitors are used in a battery line and acoustic noise occurs

The sound pressure level can be effectively reduced by implementing anti-noise measures for capacitors causing acoustic noise!

4. Mechanism by which acoustic noise occurs 

Why do ceramic capacitors cause acoustic noise?

The following explains the acoustic noise generation mechanism and the method of acoustic noise evaluation conducted at Murata.

The ferroelectrics used in multilayer ceramic capacitors always have piezoelectric properties.

When an electric field is applied, deflection occurs and the chip expands and contracts, so acoustic noise is produced.

5. Method of acoustic noise evaluation

Measurement of sound pressure level

As "sound" is the problem, the "sound pressure level" becomes the primary measurement.

The measured object is set to the operating state inside an anechoic box, and a noise meter is used to measure the sound pressure level via a microphone.

In addition, the sound pressure level frequency characteristics are checked using a FFT analyzer to facilitate evaluation and solutions.

Measurement of voltage fluctuation

To investigate the capacitor that is causing the acoustic noise, we measure the "voltage fluctuation."

With the measured object in a running state, we check to see whether a ripple voltage in the audible frequency range (20Hz to 20kHz) is applied to the capacitor.

Relationship between sound pressure level and voltage fluctuation

If the spectrum of the voltage fluctuation applied to the capacitor is at an equally high frequency as the frequency characteristics of the sound pressure level (area within the red dotted line), then we can conclude that the capacitor is causing the acoustic noise to occur.

6. Laptop PC anti-noise replacement example – battery line 

Difference in sound pressure level due to operating mode

Because the internal operation of the laptop PC changes when the operation mode is changed from a sleep state/standby screen or other mode, the sound pressure level and voltage fluctuation also change.

Therefore, it is necessary to conduct an evaluation in operation modes where acoustic noise occurs and operation modes that are prone to acoustic noise.

Battery line capacitor (simplified circuit diagram) targeted for anti-noise measures

The pink-colored frames indicate the battery line capacitors that are prone to acoustic noise, and they are targeted for anti-noise measures.

Before branching off to each circuit at the DC-DC converters, they have almost the same voltage fluctuations because they are on the same power supply line.

Therefore, it is necessary to apply anti-noise measures to all of the capacitors on this battery line.

By replacing all of the capacitors with anti-noise products instead of just some of the capacitors, the battery line anti-noise measures can further reduce the sound pressure level.

We replace the typical capacitors with anti-noise products in order on circuits [A-C].

By increasing the quantity of capacitors replaced with anti-noise products, the sound pressure level gradually diminishes.

7. Introduction to anti-noise products 

Causes of acoustic noise and countermeasures

When acoustic noise due to the impact of ceramic capacitors becomes a problem, we at Murata make proposals such as the use of anti-noise products and component placement to help improve the acoustic noise problem according to factors that have an effect on acoustic noise.

To learn more about our MLCC solutions and how they can benefit your laptop computer designs, please do not hesitate to reach out to our dedicated sales team at sales@hongdacap.com.hk

We would be more than happy to assist you and provide tailored recommendations based on your specific requirements.

Thank you for choosing Hongda Capacitors as your trusted partner in noise reduction solutions for laptop computers. We look forward to hearing from you soon and providing you with outstanding MLCC products and support.