Tag Archives: app notes

App note: Choose the right power supply for your FPGA

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Designing a power supply for FPGA includes multiple voltage, ripple management and power sequencing, here’s an app note from Maxim Integrated. Link here (PDF)

Field-programmable gate arrays (FPGAs) and complex programmable logic devices (CPLDs) require 3 to 15, or even more, voltage rails. The logic fabric is usually at the latest process technology node that determines the core supply voltage. Configuration, housekeeping circuitry, various I/Os, serializer/deserializer (SerDes) transceivers, clock managers, and other functions all have differing requirements for voltage rails, sequencing/tracking, and voltage ripple limits. An engineer must consider all of these issues when designing a power supply for an FPGA.

App note: Current-sense amplifier doubles as a high common mode instrumentation amplifier

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Application note from Maxim intergrated on utilizing a boost converter and a current-sense amplifier to form a regulator that derives +5V from -48V without isolation. Link here (PDF)

Instrumentation amplifiers (IAs) are used where gain accuracy and dc precision are important, such as in measurement and test equipment. The downside of IAs is the cost. However, inexpensive current-sense amplifiers handle high common-mode voltages and share some traits with IAs. As a result, in some applications, such as a ground-referenced -48V to +5V power converter, current-sense amplifiers can replace IAs, thereby reducing cost.

App note: Current sensing in metering applications using a pulse current sensor and ST metering devices

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App note from STMicroelectronics about current sensing using Rogowski coil together with STPMxx metering device. Link here (PDF)

This application note describes the benefits of a current sensing system for metering applications using STPMxx metering devices and a current sensor developed by Pulse Engineering Inc. (hereafter referred to as “Pulse current sensor”), based on the Rogowski coil principle. Following an overview of the Rogowski coil principle, the Pulse current sensor is introduced along with a comparison to other current measuring devices. This is followed by a presentation of the characteristics of the STPMxx family of metering devices, and the results of accuracy testing conducted using a demonstration board with the STPM01 and the Pulse current sensor.

App note: Thermal design calculations for integrated stepper motor driver solutions

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Another technical note from STMicroelectronics on fine tuning motor drivers for optimal thermal design. Link here (PDF)

One constant trend in the automotive world is the tendency to reduce the size of electronic components and the ECUs (Electronic Control Unit). While this development has many benefits for the car manufacturer as well as for the end customer, there are also challenges for the developers of these systems: especially for power drivers the design of robust applications requires an accurate estimation of the thermal power dissipation on a system level.

In this article a method to calculate the thermal power dissipation of a stepper motor driver is derived from a simple example to a model that includes the various configuration options and modes of a state of the art stepper driver, like that of ST Microelectronic’s L9942.

App note: Pop & click in audio amplifiers

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Technical note from STMicroelectronics about popping noise usually heard on audio amplifiers and how to minimize it. Link here (PDF)

Pop and click, or rather, the absence of it, is a characteristic that makes a lot of impact in the world of audio amplifiers. This is especially true for those destined for headphone-equipped applications (such as mobile phones and MP3 players).
Pop and click are the names given to the popping noise that may be heard through the headphones when you switch on or off portable audio equipment or mobile phones. The noise is generated by a voltage difference at across the output stage of the amplifier at switch-on or switch-off before it reaches its idle (or equilibrium) state.

App note: Characteristics and applications of fast recovery epitaxial diodes (FRED)

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All about ultrafast diodes app note from IXYS. Link here (PDF)

During the last 10 years, power supply topology has undergone a basic change. Power supplies of all kinds are now constructed so that heavy and bulky 50/60 Hz mains transformers are no longer necessary. These transformers represented the major part of volume and weight of a traditional power supply. Today they have been replaced with smaller and lighter transfomers, whose core materials now consist of sintered ferrites instead of iron laminations and which can operate up to 250 kHz. For the same power rating, high frequency operation significantly reduces the weight and volume of the transformer. This development has been significantly influenced by new, fast switching power transistors, such as MOSFETS or IGBTs, working at high blocking voltages (VCES > 600 V).

Apart from the characteristics of the transitor switches, the on-state and dynamic characteristics of the free wheeling diodes have a significant impact on the power loss, the efficiency and the degree of safety in operation of the whole equipment. They also play a decisive role when it comes to increasing the efficiency of a SMPS and to reduce the losses of an inverter, which clearly mandates that ultrafast diodes be used. The ultrafast diodes described here embrace all characteristics of modern epitaxial diodes, such as soft recovery, low reverse recovery current IRM with short reverse recovery times.