FEATURE THERMAL MANAGEMENT & EMC


BATTERY LIFE CR Designing medical dev


RITICAL ices for EMC


features and charging capabilit y are as important to the overall product as the ergonomic design process is.


Design verificat ion engineers must ensure that electronic design meshes wit h mechanical design, compliance and approval testing.


Some of the more st ringent aspects of t he EMC regulations require very specific limit s on insulation, electrical isolation, impedance, creepage and clearance


tolerances. Meeting t hese limit s often requires optimising t he layout of t he printed circuit board (PCB) and


organising the best use of critical tracks. It’s also important to add additional filtering and snubbers to keep


noisy than chargers, smart bat contain microprocessors and dat communication lines, adding a furt source of RFI noise.


i h h b


Anthony Robinson, design verification engineer at Accutronics, looks at the implication medical devices, in light of changes m European IEC 60601-1-2 EMC regulations


T


he medical technology (MedTech) world has experienced a growing demand for more port able and wearable devices in the last few years. However, these devices require lighter and equally portable batteries and chargers t hat use switch mode power supplies (SMPS), a technology that is prone to higher electromagnetic interference (EMI), impract ical for devices int ended for use in life critical medical environments.


Keeping pace with batt ery technology, customers now demand increasingly light er, faster and portable chargers. However, while low loss power


conversion has improved t his t echnology, a by-product of the high frequency


switching process is that electromagnetic and radio frequency interference (EMI/ RFI) is increased.


LEGISLATORY CAP ON EMI As medical devices are used in professional and home healthcare


environments, it’s important t hat EMI levels are minimised to eliminate the risk of interference with, and voltage fluctuation of, life-critical devices such


34 APRIL 2019 | ELECTRONICS


as heart monitors, electrocardiogram (ECG) and anaesthesia machines, and


ventilators. T o control allowable limits of EMI, medical technology must meet t he regulations specified in European IEC 60601-1 t hird edition legislation, covering the general requirements for t he safety and performance of medical electrical equipment. Further to this, it must also fulfil t he standards laid out in IEC 60601-1-2 fourth edit ion legislation, a collateral criterion for electromagnetic disturbances, int roducing specific tests and requirements.


CONFORMING THE DESIGN TO LEGISLATORY STANDARDS Cust omers are usually conscious of creating a device wit h a very low


suscept ibility to EMI. However, one of the


biggest challenges that companies face


is battery integration as an aft erthought, in spite of the fact that smart battery


Accutronics www.accutronics.co.uk o.uk / ELECTRONICS


“Design verification engineers must ensure that electronic design meshes with mechanical design, compliance and approval testing”


on engineer at s of modelling made to ations


The technical layout for a medical battery, specially tailored to EMC safety protocol


WORKING TOGETH


AN APPROPRIATE SOLUTION If a customer has alr


ringing and resonance at an absolute minimum. Although batteries are less i


smart batteries sors and data


s, adding a further


ER TO CREATE SOLUTION


external product, leaving a very footprint to design a batt the battery cannot b without sacrificing e


leaves just enough space t PCB, with no space for any


ready designed the aving a very limited a battery and PCB, be made any smaller nergy density . This pace to fit a blank


In situations like these, companies must work with client


mechanical, electrical and ergonomic characteristics of the batt while minimising the


and susceptibility to electromagnet interference (EMI). As the indust demand and design qualit and wearable devices grows, the cat and mouse game bet chargers will continu


electromagnetic As the industry


qualit y of portable s grows, the cat


wireless inductive charging will continue to challenge design engineers t more novel methods of batt


selection. Placing it at the forefront of the design and development ensure that smart-fe


will remain unhampered by limitations, ultimately


ndards.


To pre-empt these challenges, medical device OEMs must p


lopment process will eature progression ered by electrical


ely allowing OEMs to


improve functionality whilst complying with EMC safety standards.


t ween batteries and ue. Trends such as harging will continue engineers to produce s of battery design. e challenges, medical rioritise battery


for any components. hese, companies nts t o optimise the al and ergonomic e battery’s design, e transmission


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