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50 W two-coil wireless charger transmitter reference design

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Product overview


The STDES-50W2CWBC is a reference design that implements a Qi-compliant inductive wireless charger transmitter.

It supports two coils, which could work alternatively to increase the Rx positioning freedom.

The solution supports Qi EPP-compliant mode up to 15 W, featuring an ST proprietary protocol. It can also support 50 W or an even higher wireless power transfer.

The STDES-50W2CWBC is based on the STWBC2-HP high-integration, high-performance wireless charger system-on-chip.

It integrates: three pairs of half-bridge gate drivers, the dedicated DC-DC controllers that support buck, boost and buck-boost topologies, the high-performance Q-factor measurement hardware, the high-resolution main PWM controller, the dedicated Qi communication modulator and demodulator, the USB-PD controller, the buck DC-DC, and the charge pump.

It is suitable for one-coil and multicoil solutions in multiple topologies.

The STDES-50W2CWBC is a fully assembled reference design developed for performance evaluation only, not available for sale.

  • All features

    • Qi v1.2.4-compliant wireless charging transmitter reference design following MP-A2 topology
    • Supports Qi EPP-compliant mode up to 15 W
    • Supports up to 50 W with ST proprietary protocol (STSC)
    • Supports two coils working alternatively for positioning freedom
    • Supports USB-PD wall adapter input
    • Boost DC-DC:
      • Key products: STWBC2-HP wireless charging transmitter SoC, STL20N6F7 LV MOSFET
      • Input: 4.1 to 24 V DC (from USB adapter)
      • Maximum input current: 3 A
      • Output: up to 38 V
      • Boost DC-DC controlled by STWBC2-HP SoC to convert USB adapter input to the DC bridge voltage of the wireless charger LC tank
      • Short DC-DC by P-MOS on the control of STWBC2-HP SoC for the best efficiency
    • Main bridge:
      • Key products: STWBC2-HP wireless charging transmitter SoC, STL20N6F7 LV MOSFET, STG719 analog switch
      • Qi-compliant PID power control with frequency, duty-cycle, and voltage
      • Switching frequency: 110 to 145 kHz
      • ASK demodulation with voltage, current, and phase
      • FSK modulation
      • Protections for overvoltage, overcurrent, overtemperature, and undervoltage
      • Q-factor estimation
    • Auxiliaries:
      • Key product: STWBC2-HP wireless charging transmitter SoC
      • USB interface, embedded USB-PD stack
      • Embedded buck DC-DC to convert 5 to 27 V input to 3.3 and 5 V supply voltages
      • Embedded charge pump to double the voltage and support the embedded gate drivers
      • Reserved I²C interface to upgrade to Qi v1.3 with an external secure MCU

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Quality and Reliability

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- Industrial - Yes




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(**) The Material Declaration forms available on may be generic documents based on the most commonly used package within a package family. For this reason, they may not be 100% accurate for a specific device. Please contact our sales support for information on specific devices.

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