App note: Receiving S/PDIF audio stream with the STM32F4/F7/H7 series


App note from STMicroelectronics about electrically connecting an external S/PDIF stream to an STM32 with an S/PDIFRX interface peripheral, Link here (PDF)

The Sony/Philips Digital Interface Format (S/PDIF) is a point-to-point protocol for serial and uni-directional transmission of digital audio through a single transmission line for consumer and professional applications. The transmission of data can be done in several ways, by electrical or optical means.

The S/PDIFRX peripheral embedded in STM32 devices is designed to receive an S/PDIF flow compliant with IEC-60958 and IEC-61937, which define the physical implementation requirements as well as the coding and the protocol. These standards support simple stereo streams up to high sample rates, and compressed multi-channel surround sound, such as those defined by Dolby or DTS.

App note: Basics and low-cost solution proposals to move from legacy USB2.0 connector to USB Type-C™ connector with STM32 devices


App note from STMicroelectronics about interfacing STM32 legacy USB 2.0 to USB Type-C. Link here (PDF)

This application note is a guideline to introduce this USB Type-C connector onto platform to replace legacy USB2.0 connectors. It introduces some basis of the two new standards USB Type-C™ and the USB Power Delivery.

App note: Quad-SPI (QSPI) interface on STM32 microcontrollers


Extend memories by using external high speed memories interfaced to Quad-SPI modules on STM32 micros, app note from STMicroelectronics. Link here (PDF)

This application note describes the Quad-SPI interface on the STM32 microcontrollers and explains how to use the module to configure, program, and read external Quad-SPI memories. It describes some typical use cases to use Quad-SPI interface based on some software examples from the STM32Cube firmware package and from the STM32F7 application notes.

App note: USB audio bridge example with STM32F0 MCUs


App note from STMicroelectronics using their STM32F0 microcontrollers to playback audio stream from USB. Link here (PDF)

This application note describes a method and an example of synchronizing audio playback or audio recording with an upstream or downstream USB audio host, ensuring flawless audio listening or recording using only internal MCU resources.

Focusing on specific properties of USB microcontrollers from the STM32F0 family, the application note describes how the CRS unit can be beneficially employed for USB audio streaming synchronization. In particular, it elaborates a method of HSI48 clock frequency trimming to compensate for timing differences due to independent USB host (computer) and device (STM32F0) clock domains.

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.