POWER SUPPLIES & MANAGEMENT FEATURE
Gains from GaN Finding an alternative to silicon
for AC/DC power applications
Words by Christian Lynn, editor, Electronics P
ower Integrations’ (PI) InnoSwitch3 family of integrated circuits (ICs) is known within the market for their stringent performance: up to 100W, with an efficiency rating of up to 95 per cent, InnoSwitch3 is of a design that empowers the simultaneous management of output voltage and current to optimise control within its respective applications, through technical adaptations such as the use of magneto-inductive coupling, instead of clunkier optocouplers. With a prosperous model such as this being implemented for a variety of use cases, InnoSwitch3 has seen its share of success in the power sector. And yet, PI is looking to push its flagship family further, with the help of an advanced technology that looks to supplant the conservative silicon: GaN, or Gallium Nitride. Specifically, PI’s InnoSwitch3 variants are operating with GaN switches, instead of traditional silicon high-voltage MOSFETs. The question would be: why? To answer, one must first consider the benefits of converting to GaN over silicon. Building off of the archaic vacuum tubes from the very early stages of electronics, silicon – in this particular case, MOSFETs – was a huge improvement for power conversion technology as it requires simpler drive circuits, and reduces switching losses compared to conventional BJTs. But what advantage does GaN hold over this? Two key points come to light, when comparing the material: GaN can pass current at a more efficient rate than silicon, and in keeping with the focus on miniaturisation in electronics, provides power switches that can be made smaller without loss of performance. With this in mind, what does it bring
to PI’s table: how does GaN augment an already effective AC/DC solution? There are a number of factors to consider in
this regard. Firstly, power losses are a noticeable concern in power conversion: RDS(ON), or drain-source on resistance, for example. Tracing the various models of the InnoSwitch3, as GaN is implemented, RDS(ON) is lower than can be achieved with silicon. Furthermore, as capacitances are proportional to the size of the transistor, the minute nature of the GaN switch significantly reduces switching loss, resulting in an increase of available power from the device: the more power, the happier the application. On this consideration of proportion, heatsinks are often detrimental to a device as they take up space within the circuit, dissipating generated heat to allow for acceptable performance. GaN boasts a 95 per cent full-load efficiency rating at 230VAC, something that PI prides its InnoSwitch3 on delivering. This sanctions the use of heatsinks in adapter designs, ensuring an even smaller outcome and subsequently, cost of production, without loss of power. For a high-power USB PD application, this is a vital result: averaging out at 92.49 per cent at 115VAC and 93.24 per cent at 230VAC, InnoSwitch3 improves on silicon’s ability to deliver 88-89 per cent efficiencies in these demanding
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applications. GaN offers a manifest leap in power efficiency, and in this miniaturised age, where every nanometre and millisecond counts, this increase in percentage/decrease in wasted power is the difference between a high and even higher-quality power product. On this note, PI’s GaN-implemented InnoSwitch3 family is targeting high-end applications, pushing GaN forward as the upcoming solution to concerns over efficiency loss in semiconductors. From the aforementioned USB-PD and high-current chargers/adapters, applied to mobile devices, set-top boxes, display, appliances, networking and gaming products, the InnoSwitch is adaptable to fast-charging protocol ICs and can work independently of external components, emphasising their versatility. Balu Balakrishnan, president and CEO of Power Integrations, offers this encompassing conclusion: “GaN is a pivotal technology, offering significant efficiency and size benefits over silicon. We anticipate a rapid conversion from silicon transistors to GaN in many power applications. InnoSwitch3 looks to marry the bond between silicon and GaN: since PI launched the silicon variants 18 months ago, the newly integrated GaN- based ICs further extend GaN’s placement in the development of electronics, by advancing both the efficiency and power capability of PI’s flyback products.” A summary for silicon’s substitution: GaN is here to play, and it isn’t playing around with power and the importance of guaranteeing an efficient flow within electronics, something PI intends to capitalise on and encourage.
Power Integrations
www.power.com
ELECTRONICS | OCTOBER 2019 27
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