Page 7 - PEN eBook March 2023

COVER STORY — DESIGN Cover Story — Design

Wireless charging designs can now deliver much higher power than the mobile phone and wearable
markets require. Modern mobile phones can draw up to 50 W but for quite a limited time due to
thermal constraints. On the other hand, true high-power applications, such as laptops, tablets,

portable kitchen appliances, power tools, robots and drones and light electric vehicles, can sustain
higher power delivery and charge for prolonged periods.

However, higher-power designs beyond Qi extended power profile (EPP) are generally considered
complex and costly, as standards are still evolving, leading to interoperability and coexistence
concerns. The most discussed challenge is related to the IEC-62368 safety requirements for
touch-temperature limits on consumer portables. In addition to an efficient charging subsystem,
this also implies the need for dynamic foreign-object–detection (FOD) features that ensure
protection while enabling charging across the load range, including transients. Therefore, robust

communication protocol between the transmitter (Tx) and receiver (Rx) also becomes an essential
requirement of such high-power charging.

To meet these stringent system and regulatory requirements for higher-power wireless charging,
Infineon developed a broad range of highly integrated wireless charging ICs. These include a
USB-PD/PPS sink with an on-chip 32-bit ARM Cortex-M0 processor, 128-KB flash, 16-KB RAM
Expanding Wireless and 32-KB ROM. They are also equipped with various analog and digital peripherals, integrated

gate drivers and DC/DC controllers. The ICs are offered together with a system solution and a
Power Transfer for software stack based on Infineon’s high-power charging protocol with unique identification and

configurable protection features to maintain safe, high-power charging environments. In addition to
Higher Power Delivery the proprietary mode, Infineon’s WLCx family of products also supports the latest Wireless Power
Consortium (WPC) Qi EPP (≤15 W) specifications to enable compliant and interoperable solutions.
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High-power wireless transmitters and In the following sections, we present an overview of a typical wireless power system and some
insight into designing the solution for optimal thermal management, take a deeper dive into coil
receivers designed for mobile phone design and present an overview of Infineon’s solution features and a couple of applications to

explain why wireless power is a suitable and convenient choice for high-power products in any
fast-charging and battery-powered environment.

applications WIRELESS POWER SYSTEMS AND DESIGN CONSIDERATIONS

Wireless power systems are unique power-management solutions that include mixed-signal analog
By Nicholaus Smith, principal applications engineer and Hariom Agrawal, and digital sensing, communication circuits alongside AC and DC power-conversion stages and,
senior staff systems engineer, both at Infineon Technologies most importantly, a software stack to provide a reliable handshake between the Tx and Rx side.

The block diagram in Figure 1 shows the main functional blocks of a typical high-power inductive
Over the past decade, wireless-power–transfer functionality has been broadly adopted across wireless system.
various commercial, industrial and automotive applications. Market trends are moving toward
battery-powered products requiring higher power charging. The number of products needing In Figure 1, the incoming power source will be a DC power supply based on USB-C (PPS or PD) or
charging is increasing, and so is the need for fast-charging, high-capacity batteries. fixed-rail–voltage supply. This supply can be passed directly to or converted by an intermediate

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