Finding the optimal power switching solution for cordless handheld tools

Finding the optimal power switching solution for cordless handheld tools

Power tools have simplified the lives of professional tradespeople and craftspeople providing accurate and fast operation that is significantly less demanding on the human body than their manual alternatives. With the advent of powerful, compact and long-lasting battery technology, portable power tools have enabled work, maintenance and repairs to be undertaken almost anywhere. Consumers with a hand for DIY have also benefitted, with many power tool manufacturers providing innovative, value-for-money solutions with interchangeable battery packs.

The architecture of all cordless tools follows the same basic approach regardless of function. The power element is delivered by a motor and its control electronics, often utilizing the efficiencies offered by brushless DC (BLDC) motors. Power is supplied via a rechargeable battery pack, with energy being stored in Lithium-Ion batteries watched over by a battery management system. Finally, restorative charge is supplied by an AC/DC adapter, delivering a suitable charging voltage from the household mains supply.

What all these system blocks have in common are power switches, such as MOSFETs, which control power delivery in conjunction with matching control circuitry. With power tools often being used and carried for long stretches, several requirements drop out that impact the MOSFET selection. Efficiency, which also impacts heat generation, is high on the list. Also, in order to develop tool that lies comfortably in the hand, devices need to be selected whose packaging enables the desired form factor.

The latest generation of low-voltage U-MOS IX-H MOSFETs from Toshiba tackle these requirements, starting with the key parameters that impact power losses in switching applications; gate charge (Qg), on-resistance (RDS(ON)) and recovery charge (known as Qrr, Qoss or Eoss). This has led to best-in-class Qg vs RDS(ON) along with improvements in recovery charge that typically adversely impact EMI and, occasionally, can lead to errors in current monitoring measurements. These improvements over previous generation devices help deliver smoother motor control and extend battery life to power tools.

Packaging is also a critical element in the component selection process, both from the aspect of manufacturability as well as implementing a suitable heat dissipation strategy. The new DSOP Advance package is a dual-inline surface mount package that integrates a metal slug in the upward facing surface. Topside thermal resistance, channel to case, can be as low as 0.93°C/W combined with a low 0.88°C/W on the bottom side via the metal frame (Tc = 25°c). Such packaging advancements enable power tool developers to offer innovative form factors, as well as compact charging solutions and batteries.

To find out more about low-voltage U-MOS IX-H MOSFETS and how they support innovative cordless products, take a look at our white paper available here:

Download the Whitepaper

A modular method for high power charging design
Technologies such as vehicle-to-grid (V2G) and vehicle-to-home (V2H) where the battery in an electric vehicle (EV) returns power to the grid at times of high demand, or simply powers a home in an emergency are bringing challenges to designers of vehicle chargers
A different way to design high power charging solutions
Due to a combination of consumer demand and governmental policy to halt sales of new internal combustion engines (including in hybrid vehicles), all-electric battery electric vehicles (BEVs) are the future of personal mobility
Packaging & Configuration Advances Help Augment SiC Device Operation
Though the attributes that make silicon carbide (SiC) have undoubted value to the future of power system design, it is not just about what goes on within the semiconductor substrate itself.
Integration of SBDs into SiC MOSFET Devices
Whether they are silicon-based or use silicon carbide (SiC) technology, MOSFETs will experience switching losses that are caused by their body diodes.
Exploring SiC MOSFET Figure of Merit (FoM)
The on-resistance (RDS(ON)) of a MOSFET is an intrinsic property that causes static power losses and depends upon the inner structure of the MOSFET.
Enhancing Efficiency and Reliability with Wide VGSS and High Vth Ratings
The voltage applied between the gate and source of a MOSFET during operation is denoted ‘VGS’ and the highest possible value of VGS that can be applied without damage is VGSS. This is important as it simplifies design of the control circuit.
The Switching Benefits Derived from Using SiC
Silicon carbide (SiC) MOSFETs are able to deliver much more impressive switching characteristics than their silicon-based equivalents.
Taking a New Approach to Understanding SiC
Over recent years, there has been a lot of talk throughout the power electronics industry about the exciting performance attributes offered by silicon carbide (SiC). Though there is plenty of information available on this subject, finding a way of translating it into what this actually means for engineers’ designs has still proved difficult. Consequently, many engineers are still reluctant to migrate from the conventional silicon (Si) technology that they are already very familiar with. Unfortunately that means that they are missing out.
Innovative bi-directional EV charging
There is significant effort being made to develop next-generation charging infrastructure to support electric vehicles (EVs).
Engineers favour SiC devices for bidirectional DC-DC converters
With electric vehicle (EV) chargers delivering up to 22 kW in AC and up to 350 kW in fast DC chargers, several hundred Watts of energy can easily be dissipated as heat.
Applying a Better Approach to Servo Drive Implementation in Next Generation Robotic Systems
Servos are what enable robot movement to be initiated - with six of them usually incorporated into modern robot arms, and even more being needed for mobile AGV units and suchlike.
Advanced IGBT Technology Helps Broaden Appeal of Induction Cookers
Induction cookers are gaining ever greater commercial traction.
New bidirectional 3-phase PFC reference design speeds up the development of EV charging solutions
With hundreds of millions of electric vehicles (EVs) being deployed in the next two decades, providing a comprehensive charging infrastructure is critical. Equally critical is the efficiency of these charging points.
Bidirectional charging is an essential part of a renewable future
Synchronizing renewable energy generation to peak demand times is proving challenging and raising concerns for future renewable grids.
Implementing Advanced Servo Operation in Robotic Designs
Greater reliance on robots seems to be a certainty in the years ahead.
Game-Changing SiC-Based Reference Design for EV Charging
Electric vehicles (EVs) are now a major focus for power electronics endeavour, with a large proportion of engineers involved in finding ways to improve their performance and extend their range.
Maximising Induction Cooker Efficiency by Choosing Better Switching Components
Since it was brought in over 25 years ago, through EU Directive 92/75/EC, Europe’s colour-coded energy efficiency labelling scheme has helped people to become more energy conscious.
Transforming the Factory Floor - The Increasing Prevalence of Robotics and the Need for More Efficient Servo Technology
We are moving into an age where far greater degrees of automation will be witnessed.
Why Designers are Looking to SiC for Bidirectional DC-DC Converters
With pressure to reduce reliance on fossil fuels and other polluting energy sources, electrical energy becomes the preferred choice.
Accelerating EV Charging System Development: New PFC Reference Design Proves Invaluable Tool
The number of electric vehicles (EVs) on our roads is set to increase dramatically in the years ahead, with 323 million of them being in use by 2040 (according to a study compiled by analyst firm Wood Mackenzie).
Making Servo Drives More Efficient in a Robotic/AGV Context
With all of us currently still living in what is a socially-distanced post-COVID world, the need for an automated approach to things remains very much apparent.
More Effective IGBT Soft Switching for Induction Cookers
Induction cooking offers greater convenience and safety to users, as well as being markedly more energy efficient.
Developing Servo Drives for Next-Generation Robotics
Last year the robotics technology market, which deals with all the hardware and software components needed for building robots, was estimated to have a total worth of over $60 billion.
Changing the Rules of Engagement in USB
It is now a quarter of a century since universal serial bus (USB) first arrived on the scene. With several billion ports currently in operation globally, and many more being added each year, its market traction is unmatched by any other interface technology.
IGBTs for Induction Heating in Cooking Appliances
Clean and energy-efficient cooking is essential as the dynamic of our society changes around the world. With both parents in more and more families working, cooking is often something that is prepared in advance and then left to cook during the day using a rice cooker or slow cooker. This ensures a warm meal is ready when everyone gets home.
Facilitating Servo Drive Development in Robots and AGVs
Going back many generations, our society seems to find the subject of robotics unusually enthralling. Rudimentary automatons have been around since before the Renaissance, becoming increasingly popular during the 18th and 19th centuries and also more complex in their design.
Enhanced connectivity for e-bike applications
E-bikes are steadily gaining in market share, with growth predicted to lie between 6 and 8% until 2025. Unlike the automobile market, range is less of an issue. Instead consumers are more focused on reliability and convenience. This means longer intervals between charging and higher integration into daily life. Many e-bikes are already fitted with some sort of display, providing information on charge, speed and estimated range. But with the trend toward wearables, and with smartphones positioned at the center of such data collection, connectivity is on the list of options for e-bike users to consider.
Efficient motor control for e-bike applications
Since the 1990s, e-bikes have been steadily growing in popularity across the globe, with the market expecting to grow to around 7 million units by 2025. Although the range concerns surrounding automobiles are not as predominant in the e-bike market, it is still essential that consumers can enjoy the advantages of their electrically supported bicycle without the need to charge it up after every journey.
How to improve power conversion performance with new MOSFET technologies
To meet the demand for increasing energy efficiency in switching power conversion systems, superjunction MOSFETs have become preferred devices for energy-conscious designers. Superjunction technologies allow reduced die sizes enabling designers to reduce space and increase current density. However, new demands are coming to the fore, such as improved noise performance.
Will USB Type-C make power adapters obsolete?
Since the specification for USB Type-C was published by the USB Implementers Forum (USB IF) in 2014, the new bi-directional standard with flippable connectors has been appearing on more and more devices, including laptops, tablets and smartphones. While still in the early phase of its rollout, market research firm IHS predicts that around 500 million devices will be shipped with USB Type-C this year. And this figure is expected to quadruple to 2 billion devices in 2019.
DSOP Advance: high power density MOSFETs in a small package
Low-voltage power MOSFETs are used as main switching devices in power supply systems. The power density of these systems is increasing continuously. In order to reduce the system volume and power loss, a significant improvement of the package heat radiation of the MOSFETs is necessary. To meet this demand, a new MOSFET package called DSOP Advance (Dual Side Cooling SOP 5x6mm) has been developed. Details of the new package were presented in a paper during PCIM 2014 in Nuremburg in May.
Protecting and delivering power and data in USB Type-C designs
A world without USB is barely imaginable. Since its introduction in 1996 it has not only successfully ousted a plethora of outdated parallel and serial data transfer technologies in the world of PCs and laptops, it has established itself as a de facto charging interface for smartphone and tablets, and has even been integrated into automobiles.
High performance MOSFETs build better power tools
Cordless power tool designers face multiple challenges, many of which interact and, in some cases, compete with each other making component selection critical to producing a winning design. The battery itself is one of the most obvious trade-offs. Selecting a battery with the most energy per unit weight is key; more important is to ensure that all aspects of the design are as efficient as possible so as not to waste energy.
USB Type-C: Everything to everyone?
USB Type-C has fundamentally changed the way that devices, especially computers and peripherals, will connect in the future. Although it is part of the USB 3.1 specification, USB Type-C is truly a game-changer in that it incorporates the USB Power Delivery (USB PD) specification that allows up to 100W of power to be delivered alongside data at up to 10Gbps.
Designing USB Type-C: How to address power and data integrity challenges
With an estimated 9-10 billion ports in operation, Universal Serial Bus (USB) has become the most commonly used interface technology in modern electronics/computing designs. Though the standard continues to evolve, it needs to do so in such a way that delivers extra functionality while maximising compatibility with widely proliferated previous generations. Elevated power levels and accelerated data rates present a variety of new challenges, not least in terms of long-term reliability and signal integrity.
How MOSFET technology will boost the effectiveness solar energy installations
According to market analysis conducted by IHS, by the end of this year the world’s total installed photovoltaic capacity with be over 310GWatts - that is 8 times what it was at the start of the decade. GlobalData predicts by 2025 this capacity will have more than doubled again, reaching 652GWatts. With demand for solar technology continuing to grow, and the conversion efficiencies of photovoltaics still relatively low (though gradually increasing), there is an ongoing need to minimise the power losses of the supporting electronics (and thereby make full use of the converted energy).
Thermal Management Implications of Advances in Packaging & Silicon Technologies for Power Semiconductor Devices
The heat energy that is present in power ICs, such as MOSFETs, not only impacts on these devices’ operational performance, it also has the potential to impinge heavily on system reliability, increasing the risk of failure and shortening operational lifespan. It has a detrimental effect on the running costs involved too - as power adaptors that exhibit poor conversion efficiency characteristics will need to draw more current from the main supply, thus adding to the size of the user’s utility bills. Engineers simply cannot afford to ignore the heat dissipation issue.
Power MOSFETs explained - a 5 minute guide for the busy design engineer
Solar power is big business. As demand for solar panels grows, there is an increasing need for more compact and energy efficient electronics so that every possible milliWatt of energy harvested from the sun is captured and made available to use. Photovoltaic inverters convert the DC current produced by an array of photovoltaic cells to AC at local line voltage and frequency, ready to be fed into the grid or used to power an off-grid network. Micro-inverters that connect to just one panel each are also available – ensuring that reduced output from any panel (perhaps because of shade or snow) doesn’t disproportionately affect the output of the total array.
How do MOSFET current and thermal limitations interact?
Power MOSFETs are popular switching elements in many modern power devices. As engineers try to squeeze ever more performance and efficiency from each design, then MOSFETs are pushed to their limit. However, there is obviously a limit to each device's capability, yet there is no single means to define this limitation as it depends on a number of factors that interact.
Paralleling MOSFETs: Some key considerations
Power MOSFETs are probably the most popular switching device in modern power solutions. They are generally easy to use and semiconductor manufacturers ensure that performance increases with each successive generation. Even so, on occasion, designers find the need to operate two MOSFETs in a parallel configuration.

Innovation Centre Top

Application Posts

Product Group Posts

A new window will open