Tag Archives: app notes

App note: HT45F3630 power tool speed control switch application example

via Dangerous Prototypes

an_holtek_an0427e

All in one motor control MCU HT45F3630 from Holtek. Link here (PDF)

Aimed at the motor speed control product application area, HOLTEK has developed the HT45F3630, which is commonly used in electric drills, electric screwdrivers, lawn mowers and other similar product applications. This MCU provides a group of PWM high voltage and large current output pins which can directly drive Power MOS transistors to reduce their switching losses. Additionally, the device includes integrated over current protection and detection functions and an amplifier which allows the input signal to be amplified by 51 times, requiring a lower value current sense resistance value which will increase the overall efficiency and extend the operating time. When an over current event occurs, the PWM switching will be shut off by hardware to achieve immediate protection.

App note: How to measure thermal resistance of LED emitters and LED arrays

via Dangerous Prototypes

an_lumileds_wp23

Another white paper from Lumileds about LED thermal resistance. Link here (PDF)

Thermal performance is the most critical factor of a well-designed LED lighting system. A lighting system with proper thermal design has higher efficacy, meaning more light can be extracted using less energy, and better long term reliability.

App note: Flash for “Selfies”

via Dangerous Prototypes

an_lumileds_wp26

Effective front facing camera flash discussed in this white paper from Lumileds. Link here (PDF)

Smartphones are ubiquitous in everybody’s daily lives, a trend that shows no sign of slowing. A key component of the smartphone is the camera, which has gained market share over Digital Still Cameras due to its convenience.

As the demand for smartphone cameras increases, sensor makers are continuously working to improve the resolution and while 20MPix capability gained in importance for the main camera of the smartphone, the resolution race has begun for the front camera. With the rise in popularity of “selfies” and the 5 to 8 Mpix resolution for the front camera, it is not surprising that camera flash is starting to be more readily implemented for front cameras also. However, to make a successful front flash that captures an ideal “selfie,” there are certain illuminance requirements and shorter flash pulses that are recommended.

App note: DAC ICs: How many bits is enough?

via Dangerous Prototypes

an_ad_AN-327

A very old application notes from Analog Devices that tells about Nyquist Theorem, sampling rate and quantization used on DACs. Link here (PDF)

At the heart of every digital audio playback system lies the single-most critical component for high-fidelity audio: the digital-to-analog converter (DAC). These converters handle the delicate task of translating the 16-bit binary words encoded on the disc or tape into corresponding analog signals worthy of amplification and, ultimately, of the human ear.

App note: Influence of control loop by an output filter

via Dangerous Prototypes

an_wurth_elektronik_ANP006

Application note from Würth Elektronik about the effect of filters that are added to the output of switching regulators. Link here

The output voltage of switching regulators has a voltage ripple that can disturb with electrical power supplied circuits and lead to electromagnetic disturbances. Thus output filters are often used for noise suppression, which may under certain circumstances have an influence on the control loop. To prevent output power losses it may be necessary to compensate the control loop.

No matter what switching regulator topology is used, as a result of the parasitic series resistor ESR and the parasitic inductance ESL of the output capacitor, the output current causes an undesired residual ripple. Depending on the capacitor type selected, a relatively large residual ripple is created, which has varying wave forms. A common electrolytic capacitor, for example, can have a ripple voltage of up to a few hundred millivolt, depending on the output power of the switching regulator. If a ceramic capacitor is chosen, the ripple voltage may only be a few tenth of a Volt.

App note: Ceramic multilayer capacitors in HF SMPS applications

via Dangerous Prototypes

an_avx_mlchf

Development and improvement of ceramic multilayer capacitors in high frequency power supply filtering, a technical note from AVX. Link here (PDF)

There has been an explosion of interest in the use of ceramic capacitors for high frequency power conversion applications. This interest is compounded with new designs striving for higher frequencies, smaller sizes and greater efficiencies. This application is an ongoing and mutual development of ceramic values, processes and sizes that were never realized prior to this application. In more and more cases, the ceramic capacitor is dictated by performance requirements never attainable in the previous styles of electrolytic and tantalum.