Monthly Archives: October 2022

App note: Buck-Boost charger MOSFETs

via Dangerous Prototypes

Selecting the desired MOSFET fit for Buck-Boost for higher efficiency in power supply and battery charging section discussed in this app note from Alpha & Omega Semiconductors. Link here (PDF)

The wide adoption of USB Type-C PD makes the notebook PC charger move to four MOSFET buck-boost charger topology to allow for wide range input voltage (5-20V). After a suitable controller is selected, the specified Power MOSFETs in buck-boost charger are essential for achieving higher efficiency and high-power density design.
In this application note, we will only discuss the USB power delivery specification for an adapter supplying 5A/100W and expect the reader to understand the basic operation of buck-boost topology. It is critical to select suitable MOSFETs regarding efficiency, thermal, and space limitation, to meet the system-level requirements. 30V MOSFETs can be used for input voltage below 20V.
Based on given wide input voltages, output voltages, and current, the designer must understand the tradeoff among the different loss mechanisms in the MOSFET. These MOSFET losses include: switching loss, conduction loss, and reverse recovery loss. Losses are minimized by selecting the best MOSFETs from its electrical characteristics.

Name that Ware, October 2022

via Hacking – bunnie's blog

The Ware for October 2022 is shown below.

I think there should be ample clues in the first picture to guess the ware, but I included a couple of close-ups of the circuits because I love it when circuit boards document their functions so clearly. You can basically read the schematic directly off the traces. I also enjoy the motif of “here’s a ROM but no microprocessor” (the ROM is the ceramic-packaged 2716 in the top right of the first photo, with the label covering the UV erase window). ROM-based sequencers/FSMs and lookup tables were fairly common for this vintage, but these days most designs use ROMs exclusively to store code that is accessed by a CPU.

Winner, Name that Ware September 2022

via Hacking – bunnie's blog

The Ware for September 2022 is a Kenwood ProTalk TK-3300 2 watt 450-470 MHz two-way radio, and thanks again to jackw01 for contributing the photos. Gratz to TRM for totally smashing this one, email me for your prize. Unfortunately since the ware is contributed I don’t have the original PCB to take a better photo of the SMA connector. That being said, I do have an additional image of the die-cast metal housing that the board was mounted in:

I think the “shroud” is actually the connector screwed into that metal housing. In order to photograph the PCB separately, it looks like Jack had to desolder the connector and leave the SMA connector in the housing. I agree with Barnaby’s assessment that there was a concern about reinforcing the connector, since the whip antenna is basically an excellent torque arm for forcibly removing such connectors from the PCB.

App note: Design considerations on Solid-State Relays in DC configuration

via Dangerous Prototypes

Solid-state relays uses app note by Vishay in DC application with resistive, capacitive and inductive loads. Link here (PDF)

A solid-state relay (SSR) is an electronic switching device in semiconductor technology. An SSR has a high efficient GaAlAs infrared emitter on the input which is optically coupled to the high performance MOSFETs at the output.
An SSR is capable of switching AC loads where both output MOSFETs are required as well as DC loads where one MOSFET, or two in parallel, can be used.

App note: TJA1101B automotive Ethernet PHY

via Dangerous Prototypes

App note from NXP introducing their network solution TJA1101B to handle Ethernet in automotive environment. Link here (PDF)

The TJA1101B is a 100BASE-T1 compliant Ethernet PHY optimized for automotive use cases. The device provides 100 Mbit/s transmit and receive capability over a single unshielded twisted pair cable, supporting a cable length of at least 15 m. Optimized for automotive use cases like IP camera links, driver assistance systems and back-bone networks, the TJA1101B has been designed for automotive robustness and ISO 26262 ASIL-A compliance, while minimizing power consumption and system costs.