This article is the second part of a two-part series exploring how to design a secondary-side synchronous rectifier for ultra-small, fast charge adapters. Part I discussed the topology designs and power supplies for synchronous rectifiers. Part II will review how a synchronous rectifier opens and shuts down, and how new devices utilize quick shutdown technology. A self-powered circuit provides ...

Mobile devices — such as mobile phones and laptops — are integral to the modern world. The development of mobile devices has accompanied a demand for small, lightweight, and fast-to-charge adapters. Major manufacturers are rushing to introduce ultra-small, fast charge adapters (see Figure 1). This article is the first part of a two-part series exploring how to design a secondary-side synchr...

Due to the rapid development of mobile devices in the last decade, cell phone applications have expanded into every aspect of society. In day-to-day life, few people leave their cell phone, even for a few minutes. As a result, high battery capacity and fast charging speed has become one of the most critical features for cell phones, and the demand for adapters with higher power ratings and higher ...

Because optical encoders are functionally similar, “resolution” is often used as a main characteristic for magnetic encoders (a device providing the angle of a magnet attached to a mechanical shaft, under a digital form). Resolution is a key parameter since it indicates the smallest angle that the sensor is capable of resolving. Unfortunately, when comparing products, users may often be misled, as...

In Part I of this series, we covered the bipolar stepper motor’s three control modes as well as its mechanical structure, including dual full-bridge drive. In Part II, we will discuss microstepping and how it controls the dual full-bridge drive. Previously, half-step stepping mode was introduced as a combination of single-phase stepping and full-step stepping to obtain more electrical angle pos...

When designing a motor control circuit, it is vital to determine how to deliver the high current required to drive the motor. Designers must choose whether to use monolithic integrated circuits that have internal power devices, or gate driver ICs and discrete external power MOSFETs. This article discusses the advantages and disadvantages of each approach and provides guidance on when to choose eit...

In the intelligent era, stepper motors are widely used due to their unique open-loop position control performance. Each device has specific requirements that ensure there is a smooth output torque while the stepper motor rotates. Rotation stability is closely related to the motor’s physical construction as well as its control mode. This article introduces the bipolar stepper motor and discusses i...

Power over Ethernet (PoE) is a power supply scheme that uses a network cable to transmit power. This scheme includes power sourcing equipment (PSE), a powered device (PD), and a network cable. With the popularity of IP device applications, PoE has become widespread among users due to its low installation costs, scalability, ease of management, and global compatibility. After over a decade since t...

When starting a DC motor, large currents can be required that place a burden on the motor driver and power supply. This article will discuss using the current regulation function integrated into many motor driver ICs, while using examples from Monolithic Power Systems (MPS) to address high-current conditions. In many cases, using current regulation can allow designers to use a smaller motor drive...