Inquiry about 6.78MHz operation for wireless power transfer

Dear Engineer,

I purchased the LTC4442 for a wireless power transmission experiment with a frequency of 6.78MHz. In particular, I am using the LTC442 to drive the TX power switch. The LTC4442 works well at frequencies below 500kHz but does not operate above 500kHz. That is, the output of the LTC4442 is not generated even though the square wave(V_Peak=5V) is delivered to the input.

What is the operating frequency range of the LTC4442?

Is the LTC4442 capable of operating at 6.78MHz?

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Other components for LTC4442,

    - Switches : ZXMN6A11Z (60V N-CHANNEL ENHANCEMENT MODE MOSFET)

    - Diode : PMEG3050EP (A low VF MEGA Schottky barrier rectifier)

    - Capacitor : 0.22uF (SMD Type)

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Thank you.

Parents
  • 0
    •  Analog Employees 
    on Feb 9, 2018 10:50 PM over 2 years ago

    Hi Ish,

    The 6.78MHz frequency square wave means 150ns period and 75ns “on” and “off” time each.

    Looking at the datasheet cover page waveform:

    The propagation delay from input to TG is ~50ns

    The rise and fall time of TG or BG is ~10ns

     

    The above numbers are tested from a 3nf capacitor loading.

    You mentioned 0.22uf capacitor. Is that the BST capacitor or load capacitor?

    I suspect the LTC4442 is not be the right choice as the 6.78MHz is too high for the part.

Reply
  • 0
    •  Analog Employees 
    on Feb 9, 2018 10:50 PM over 2 years ago

    Hi Ish,

    The 6.78MHz frequency square wave means 150ns period and 75ns “on” and “off” time each.

    Looking at the datasheet cover page waveform:

    The propagation delay from input to TG is ~50ns

    The rise and fall time of TG or BG is ~10ns

     

    The above numbers are tested from a 3nf capacitor loading.

    You mentioned 0.22uf capacitor. Is that the BST capacitor or load capacitor?

    I suspect the LTC4442 is not be the right choice as the 6.78MHz is too high for the part.

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