Application note from ON Semiconductors discussing possible abnormalities on High voltage gate driver when operating on short pulses. Link here (PDF)
The High−Voltage Integrated Circuit (HVIC) gate driver family is designed to drive an N−channel MOSFET or IGBT up to 600 V. One of the most common methods to supply power to the high−side gate drive circuitry of the high−voltage gate drive IC is the bootstrap power supply. This bootstrap power supply technique has the advantage of being simple and low cost. However, duty cycle is limited by the requirement to charge the bootstrap capacitor and serious problems occur when extremely short pulse width is used in the application system. This application note explains the features of HVIC gate drivers and provides recommendations to avoid short pulse−width issues in the application.
App note from ON semiconductors about repurposing a buck converter to produce negative voltages. Link here (PDF)
Applications in the electronics industry ranging from sensor−based designs to power amplifiers are periodically faced with the requirement to generate a negative voltage rail. Although many transformer−based designs, charge pumps and other methods have been used to meet such a requirement, the inverting buck−boost topology stands out as simple to design and can save on power and board space too.
With power budgets in many applications already stretched, and PCB real estate limited due to the high levels of functionality incorporated in many new products, power devices that use an inverting buck−boost topology can prove extremely valuable to systems designers.
A Buck regulator can be reconfigured to generate a negative output voltage from a positive input voltage using the inverting buck−boost topology. Unlike a buck regulator, the Inverting buck−boost transfers energy to the output through the output diode during the ’Off’ time. For this reason, users must keep in mind that the average output current is always less than the average inductor current.
Another app note from Richtek introducing solutions for reducing the input voltage spike on power switches. Link here
The power switch is a low voltage, single N-Channel MOSFET high-side power switch, optimized for self-powered and bus- powered Universal Serial Bus (USB) applications.
In worse operating condition, an input voltage spike may over the chip’s maximum input voltage specification to damage the chip.
Investigative app note from Richtek about the component failure point caused by EOS. Link here (PDF)
Failures in power ICs are often the result of Electrical Over Stress (EOS) on the IC input supply pin. This report explains the structure of power IC input ESD protection and how ESD cells can become damaged due to EOS. Common causes for input EOS are hot-plug events and other transient effects involving wire or trace inductance in combination with low ESR ceramic capacitors. Solutions are presented how to avoid EOS via special circuit and system design considerations.
Another app note from Richtek, this time about transient load testing on power converters and how you can make a simple and low cost fast transient tool. Link here (PDF)
Load transient testing is a quick way to check power converter behavior on several aspects: It will show the converter regulation speed and can highlight loop stability problems. Other power converter aspects like input voltage stability, slope compensation issues and layout problems can be quickly spotted as well. This application note will explain the practical use of load transient testing to diagnose DC/DC power converter problems.
An application note from Richtek on buck converter used in automotive application. Link here (PDF)
Automotive environment can be quite harsh and designing electronics that need to work reliable in this environment takes special care, and often requires automotive qualified parts.
When designing voltage regulators that need to step down an intermediate voltage from the car battery supply, the car battery voltage fluctuation needs to be taken into regard.
The full operating temperature range needs to be considered for all aspects of the design, and all component parameters have to be checked over temperature.
The car radio receiver is nearby, which means that any switch-mode converter radiated emission needs to be minimized to avoid switch noise being coupled into the car radio receiver.
More Li-ion battery applications from Richtek. Link here (PDF)
Lithium-Ion batteries have several advantages when compared with other battery types: They are light weight, and energy density of lithium-ion is typically twice that of the standard nickel-cadmium. Li-Ion batteries have no memory effect, and the self-discharge is 6 ~ 8 times less compared to nickel-cadmium. The high cell voltage of 3.6 volts is often sufficient to power applications from a single cell. These properties make Li-Ion batteries very popular in modern portable electronic applications.
App note from Richtek about several aspects of switching chargers for single cell Li-Ion batteries. Link here (PDF)
Longer battery life and shorter charging times are some of the challenges in battery management in modern hand-held applications like Smart-Phones, Tablet PCs, POS and other portable equipment.
Devices with powerful processors are more power hungry and require larger capacity batteries to guarantee battery life. To quickly charge large capacity batteries, powerful high current chargers are needed. Linear chargers have too limited charge current capability for this purpose, so switching charger topology has to be adopted.
Application note from Vishay on power and voltage limitations of solid tantalum capacitors for both low and high frequency applications. Link here (PDF)
Solid tantalum capacitors are preferred for filtering applications in small power supplies and DC/DC converters in a broad range of military, industrial and commercial systems including computers, telecommunications, instruments and controls and automotive equipment. Solid tantalum capacitors are preferred for their high reliability, long life, extended shelf life, exceptional stability with temperature and their small size. Their voltage range is 4 to 50 volts for the most common types. Tantalum chip capacitors for surface mount applications are manufactured in very small sizes and are compatible with standard pick-and-place equipment.
Lifetime estimation methods for elcap app note from Jianghai. Link here (PDF)
Aluminum Electrolytic Capacitors (“alu-elcaps”, “elcaps”) are essential for the function of many electronic devices. Ever increasing for enhanced efficiency, the expanding utilization of renewable energy and the continuous growth of electronic content in automotive applications have driven the usage of these components.
In many applications, the lifetime of electronic devices is directly linked to the lifetime of the elcaps inside. To ensure reliable operation of electronic devices for a defined period, a thorough knowledge of the vital properties of elcaps is mandatory.
The present article outlines the construction of elcaps and explains related terms like ESR, ripple current, self-heating, chemical stability, and lifetime. Two estimation tools for obtaining elcap lifetime approximations in an application are introduced and illustrated by an example.