DESIGN & PRODUCTS POWER SUPPLIES & BATTERIES
AirFuel’s resonant technology allows for a more flexible nearfield
charging experience and offers more positioning freedom
over inductive solutions. This technology is suitable for devices
that have high metallic content, have compound shapes (unlike
a smartphone), or can benefit from multi-device charging.
But there are some challenges with resonant charging. The
power has to be switched very fast. This means that the MOSFET’s
gate characteristics have to fit in the 150ns cycle requirement.
On the other hand, minimum parasitic capacitances have
to be reached, while efficient voltage conditioning to control the
output power is needed.
Infineon, through the partnership with Spark, is the only
company that offers both inductive and resonant technologies,
allowing a custom-tailored solution that uniquely meets all application’s
requirements (figure 3a and 3b). Both inductive and
resonant solutions can conform to a standard or be proprietary
to the application, depending on the market needs.
Fig 3: Infineon/Spark Connected product roadmap with
reference designs to address both consumer/industrial (3a)
and automotive (3b) wireless charging solutions.
Robust and reliable FOD
Standard Foreign Object Detection (FOD) methods rely on the
large primary coil winding for detecting foreign objects, which
reduces sensitivity and signal to noise ratio. Smaller objects are
difficult to detect, due to the small impact on the magnetic field
of the much larger primary coil. Existing transmitter solutions
measure the parameters needed for the power loss calculation
(voltage and current) at the DC supply of the inverter. This distorts
the measurement when compared with the actual values at
the coil, causing an inaccurate transmitter loss calculation.
The Infineon/Spark solution is Qi certified and fully meets Qi
FOD functionality and performance. The solution employs more
accurate measurement techniques, which improve the performance
of the standard Qi FOD method: actual voltage and current
are used in the calculation and not the inverter DC power.
The solution is more accurate and can detect smaller foreign
objects. It prevents overestimation of losses (Foreign Object not
detected), or underestimation of losses (FOD fail with no object
present). The transmitter employs AI and machine learning to
determine if the charging environment is safe when metallic
objects are present.
Flexible software-based architecture
Rather than rely on an application specific IC for protocol and
power delivery, the strength of the Infineon/Spark wireless
charging solution lies in its modular software-based architecture.
Wireless power is continually evolving, as standards mature,
and new products and applications are introduced to the
market. The high software content of the solution allows a common
hardware architecture to be used across several reference
designs, with each reference design flexible enough to support
several types of applications. In addition, future changes to the
wireless charging standards can be supported by a software
upgrade.
Dedicated wireless power controller based
on AURIX and XMC
There are dedicated wireless power controllers for wireless
charging based on AURIX and XMC families. The AURIX
wireless power ASIC like the SAK-TC212S-8F133SC help
the next-generation in-cabin wireless charging systems meet
strict automotive safety, security, environmental and regulatory
requirements, while still enabling industry-leading charging performance
and efficiency. This controller works seamlessly with
Infineon’s power and interface devices to provide a complete
charging solution for smartphones and other connected devices.
The controller supports 15W charging for today’s standard
Qi and fast charge smartphones and supports future standards
with a software update. Other key features of the solution are:
Special power drive stage with improved EMI performance of 10
- 15dB over existing solutions; flexible FOD with improved accuracy
that can detect smaller objects; support of custom coils
and multi-coils; charging two devices using a single controller;
full power charging with a 6 - 19V input supply; and built-in
security functionality meeting latest automotive requirements.
The wireless power controller XMC6521SC-Q040X and the
other members of this series based on the ARM Cortex-M0 core
work seamlessly with Infineon’s power devices in a scalable and
cost-effective architecture to provide a complete charging solution
for everything from a fast charge smartphone, to a 45W laptop
computer, to a 80W drone and beyond. Other key features
are the support of existing standards and fast-charge devices;
full power charging without exotic thermal management; high
efficiency charging rates equivalent to wired charging; support
of custom charging profiles and industry standards on the same
hardware; flexible FOD with improved accuracy; and support of
custom coils and multi-coil architectures.
Reference designs
for next generation applications
Working with Spark Connected Infineon provides complete reference
design roadmap for both inductive and resonant wireless
power solutions (see figure 2) that support many of the current
and next-generation wireless power applications: for on-the-go
charging, whether in the car, at home or in public places. These
reference designs include the hardware design, bill of materi-
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