App note: USB Type-C protection and filtering


STMicroelectronics’ solution for simplifying USB Type-C protection and filtering using transient voltage suppressors, common mode filtering and proper board layout. Link here (PDF)

The USB interface has been present on the market for nearly 2 decades and thanks to that, nowadays it is quite obvious for everybody to connect electronic devices in this manner. However, the presence of different types of connectors: type A, type B, mini USB, micro USB etc., makes difficult and complicated the choice of the right one. For this reason USB Type-C, a unique connector to drive audio and power data up to 5 or 10 Gbps, is now available.

Due to the fact that for its own nature a connector is a link to the outside world, it may be exposed to a lot of disturbances which can ruin the transceivers. Moreover, the high-speed links radiate therefore an efficient filter has to be used to solve antenna desense.

STMicroelectronics has developed some specific protection devices and common mode filters with optimized performance and layout.

App note: How to implement an SCR or a Triac in hybrid relay applications


Another app note from STMicroelectronics on SCR or Triac hybrid with mechanical relay to decrease power loss and manage inrush current. Link here (PDF)

This document gives some key information about the design of the solid-state silicon AC switch stage of a hybrid relay, which can drive resistive, capacitive or inductive AC loads, such as: heater resistors, motors for industry, power tools or appliance applications.

App note: AC switches – Is a positive power supply mandatory for my application, or could a negative output work also?


App note from STMicroelectronics about the usage of a negative supply in controlling AC switches and their benefits, Link here (PDF)

In this application note we explain the reasons why some appliance designers might choose a positive power supply. This selection is based mainly on the choice of switched mode power supply (SMPS). Some specific applications cases, may also lead to the choice of a positive power supply.

Using a power supply with a positive output is not convenient for all applications. For example, a negative supply is preferred to drive AC switches. We provide here an alternative solution which allows a negative output to be implemented whenever possible. Further, many solutions allow both a negative and a positive output (for the microcontroller) to be implemented.

App note: Current sharing in parallel diodes


Application note from STMicroelectronics on the performance of each diode in a parallel diode connection and how the forward voltage dispersion can have a great impact over thermal effect on the current imbalance. Link here (PDF)

The use of diodes in parallel is commonly found in power electronic design. An important consideration for this practice is the current sharing between diodes due to the difference of electrical characteristics. This application note highlights the cause of the behavior of several diodes are connected in parallel. Some recommendations will be given to help the designer to produce a safe design. An electro-thermal model is described which simulates the current and junction temperature of each diode for given application conditions. This tool is illustrated using an example.

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


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: Watt-hour meter based on the STM32F101 microcontroller


ARM Microcontroller based watt-hour meter implementation from STMicroelectronics. Link here (PDF)

This document describes, in detail, the hardware and software implementation of a watthour meter using the STM32F101 microcontroller. This cost effective watt-hour meter uses shunt with an operational amplifier as a current sensor, an embedded 12-bit ADC for current and voltage measurement, GPIO for LCD management, and a lot of other peripherals for communication, tamper detection, keyboard, and power disconnection. Powerful architecture of the STM32™ microcontroller allows sampling at 1 Msps. The high sampling rate makes it possible to use methods for ADC resolution enhancement.

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


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


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.