App note: Method to reduce the output ripple & noise of power supplies

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Another app note from Aimtec on power supplies and how to minimize their output noises. Link here

The switching power supplies have the fundamental advantage of high efficiency i.e. low power dissipation when compared to linear voltage regulation. However, there exists an important consideration concerning the presence of ripple and noise at their outputs. If the ripple and noise are left unfiltered their levels may be sufficiently high to adversely affect other devices connected to the same power supply. Fortunately there exists methods to cost effectively reduce the impact of ripple and noise.

App note: Best design and layout practices for SiTime oscillators

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SiTime’s app note about how to properly route an oscillator’s PCB traces. Link here

Proper decoupling, bypassing, and power supply noise reduction is important in many applications to ensure optimal performance for oscillators. A common strategy is to place capacitors near high speed devices on a printed circuit board (PCB). These capacitors serve important functions:
– Provide instantaneous current to the component
– Reduce noise propagation through the system
– Shunt the power supply noise to GND
The following sections describe decoupling, bypassing, noise rejection, and power supply condition recommendations for SiTime’s single-ended and differential timing devices.

App note: Frequency measurement guidelines for oscillators

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Application note from SiTime about frequency measurements and how some methods may not gauged accurately. Link here

Every digital electronic device requires a reference clock and oscillators are widely used to serve that purpose. Verifying frequency characteristics of high performance devices requires accurate frequency measurement. This document contains an overview of various frequency measurement methods and instruments and is intended to help the users of SiTime MEMS oscillators take accurate frequency measurements.

App note: Alkaline battery low-voltage indicator

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Battery low-voltage indicator made from two new comparators TSM9118 and TMS9119 from Silicon Labs. Link here (PDF)

In many battery-powered systems, a user would like to know when it is time to replace the batteries before they are completely discharged, causing the device being powered to fail completely. Alkaline batteries have an open cell voltage of about 1.5 V. As they are discharged, the voltage slowly drops. When the cell voltage reaches about 1.25 V, they have delivered about 90% of their stored energy.

App note: A practical look at current ratings

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An app note from Alpha & Omega Semiconductors about proper way of evaluating MOSFET’s power handling capability based on how much loss it will generate based on the application conditions. Link here (PDF)

System designers are often faced with the task of selecting the most suitable power device from a wide array of products from different manufacturers with very similar ratings. While a detailed parameter by parameter comparison is technically the most correct way of selection, it is not the most practical and designers resort to making their first cut based on 3-4 simple parameters. Among these are package, voltage and current ratings, Rdson etc. In this article we will take a close and practical look at the current rating. For purposes of illustration we will focus on Mosfets in low and medium power packages, but the considerations can be applied to other technologies as well.

App note: Performance capability of the SO8-FL package

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MOSFET SO8-FL package app note from ON Semiconductors provide same thermal performance as metal top package with heat sink attached. Link here (PDF)

The SO8−FL package can deliver high power density and provides excellent thermal dissipation to create a high efficiency, cool design environment when properly cooled. Metal−top devices attempt to remove heat easier through direct contact to the source. This application note provides a comparison of an SO8−FL device with a metal top device of comparable die parameters, and will show that the SO8−FL and metal top devices have comparable thermal performance. Furthermore, it will be shown that while the package itself influences thermal performance, the use of a heat sink provides the largest improvement to thermal dissipation, regardless of package.

App note: PCB design guidelines that maximize the performance of TVS diodes

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Correct TVS diodes location on the PCB provides optimal protection from surge, an application note from ON Semiconductors. Link here (PDF)

Transient Voltage Suppressors (TVS) avalanche diodes and diode arrays can be used to protect sensitive electronic components from the surge pulses that arise from ESD and EMI. The small size, fast response time, low clamping voltage and low cost of TVS diodes provides for an effective solution to prevent surge problems. Avalanche TVS diodes and diode arrays are relatively simple devices to use to suppress surge voltages. Only a few PCB design rules must be followed to optimize the ESD and EMI immunity level of the protection circuits.

App note: Press-Fit technology

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PCB Power connection solution from Würth Elektronik, Link here

As a solder free fastening technology, press-fit technology frequently offers an attractive alternative to simple soldering technology. An effective electrical press-fit connection is created by pressing a pin into the plated through hole of a circuit board and – as part of cold welding process – generating a gas-tight electrical connection.

The trough-hole plating for a press-fit system is essentially made in the same way as are the holes for accepting components for THT soldering. Thus there are no changes required in the pcb manufacturing process. One outstanding characteristic of the press-fit system compared to the soldering system is that it produces not only an electrical connection but also an extraordinarily strong mechanical connection between the inserted components and the PCB.

App note: Going wireless with magnetic shielding

Efficient magnetic shielding application note from Würth Elektronik, Link here (PDF)

Magnetic Field Interferences are increasing in electronic devices due to a number of factors including reduced separation distances of PCB’s, Integrated Circuits and many other sensitive components. In addition to this the extended use of magnetically coupled communication technologies (Qi-WPC, NFC, RFID, PMA, A4WP, WCT…) leads to more complex layout and proximity considerations.

With Ferrite materials it is possible to manage and predict magnetic flux flow and thereby improve efficiency of power transfers, increase distances of near field communications and of course avoid additional unwanted coupling effects which could lead to losses or noise.