App note: Load switches for mobile and computing applications

App note from Nexperia presenting simple load switches in mobile and computing applications. Link here (PDF) There are several reasons why a circuit or subsystem is required to be disconnected from the power supply using a load switch. A very simple and very common reason is that it helps saving power. An unpowered subsystem can […]

App note: Driving solenoids in automotive applications

App note from Nexperia about various solenoid driver used in automotive. Link here (PDF) There are a wide variety of solenoid drive circuit topologies. Most of them use MOSFETs in various configurations and driving modes. In this application note four of them will be discussed: solenoid driver with free-wheeling diode, solenoid driver with MOSFET avalanching, […]

App note: Power Battery Charger Calibration Fixture

Automated battery charger calibration fixture using Holtek’s ASSP MCUs. Link here (PDF) Power chargers for electric bicycles, electric motorcycles and power tools, etc., are all calibrated before delivery, thereby correcting any charging parameter drifts due to external component tolerances. This will ensure the output voltage and current conform to their specifications. However, traditional applications are […]

App note: BA45F55xx with power line transceiver

App note from Holtek on power line transceiver found on their BA45F55xx MCU. Link here (PDF) A Power Line Transceiver is a fire protection dual-line bus which is used as a data transceiver. The master gives a command to the slave using a voltage signal modulation method while the slave responds to the master using […]

App note: Op amps for MEMS Microphone preamp circuits

App note from TDK on design considerations of preamps used on MEMS microphones. Link here A microphone preamp circuit is used to amplify a microphone’s output signal to match the input level of the devices following it in the signal chain. Matching the peaks of the microphone’s signal level to the full-scale input voltage of […]

App note: Analog and digital MEMS microphone design considerations

App note from TDK about the things to consider when integrating analog and digital MEMS microphones into a system design. Link here (PDF) Microphones are transducers that convert acoustic pressure waves to electrical signals. Sensors have become more integrated with other components in the audio signal chain, and MEMS technology is enabling microphones to be […]

A sensitive, frequency-modulated dip meter capable of measuring resonator Q

Qrp Gaijin’s version of a dip meter to measure resonator Q: A highly-sensitive, narrow-band frequency-modulated dip meter offers a simple way to measure resonator Q. I have been working with an unusual dip meter circuit recently that has some interesting properties. The dip meter, also called a grid dip meter, is a simple homebrew instrument […]

Reverse engineering RAM storage in early Texas Instruments calculator chips

Reverse engineering RAM storage in early Texas Instruments calculator chips: Texas Instruments introduced the first commercial single-chip computer in 1974, combining the CPU, RAM, ROM, and I/O into one chip. This family of 4-bit processors was called the TMS1000. A 4-bit processor now seems very limited, but it was a good match for calculators, where […]

Powering up an HP YIG tuned oscillator

Kwong explained the operation principle of an YIG tuned oscillator and demonstrated the tuning characteristics: I was going through some of the components I accumulated over the years and stumbled upon a Hewlett Packard YIG tuned oscillator (part number 5086-7023) that I bought a while back. This YIG oscillator was made for a frequency extension […]

App note: Driving electronic paper displays (E-paper)

Silicon Labs’ app note on driving E-paper with their EFM32 micro. Link here (PDF) Electronic Paper Displays (EPDs) are types of displays that are reflective and bistable. Reflective in this case means that they rely solely on ambient light and does not use a backlight. Bistable is the property of retaining an image even when […]

App note: Designing with an inverted-F 2.4 GHz PCB antenna

PCB design guide for an inverted-F 2.4 GHz antenna from Silicon Labs. Link here (PDF) One of the main reasons to use a PCB antenna is to reduce cost. Since the antennas are printed directly on the board, they are generally considered to be free. On boards with room to spare, this will be true. […]

App note: Secure hash algorithms back to basics

Maxim Integrated’s introduction to SHA security. Link here (PDF) This application note goes over the basics of Secure Hash Algorithms (SHA) and discusses the variants of the algorithm. It then briefly touches on how the algorithm is used for authentication, including the concept of a Hashed Message Authentication Code (HMAC). It concludes by looking at […]

App note: Optocouplers in on-board chargers and battery monitoring systems

App note from Vishay on how optocouplers play a role on safety for Electric vehicles. Link here (PDF) The number of electric vehicles on the roads is steadily growing, increasing the need for safe and reliable battery systems and high efficiency battery chargers. Modern electric vehicles use battery systems with voltages up to 1000 V […]

Reverse-engineering the classic MK4116 16-kilobit DRAM chip

Ken has written an article on reverse-engineering the classic MK4116 16-kilobit DRAM chip: Back in the late 1970s, the most popular memory chip was Mostek’s MK4116, holding a whopping (for the time) 16 kilobits. It provided storage for computers such as the Apple II, TRS-80, ZX Spectrum, Commodore PET, IBM PC, and Xerox Alto as […]

App note: Control solution using logic, analog switches, and discrete semiconductor devices for reversing a one-phase motor

App note from Littelfuse on solution to control split-phase motor using logic devices and triacs. Link here (PDF) In the huge variety of the AC motors, one-phase motors are an excellent option when only the single-phase power is available to supply electrical energy which motors require to operate. One of the most common single-phase motors […]

App note: Circuit protection solution for lithium cells

App note from Littelfuse on PolySwitch PPTC for lithium cells protection. Link here (PDF) Primary lithium cells (i.e., AA and 2/3A) and rechargeable lithium cells (i.e., 18650, 17500, and prismatic) are used in many portable electronics applications, such as laptop or notebook computers. Their popularity is based on the fact that they offer high energy […]