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How are Power Mosfets driven by Gate Drivers if the Vgs needs to be so high?

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  • #1 21681166
    Michael Ferguson
    Anonymous  
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  • #2 21681167
    Rick Curl
    Anonymous  
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  • #3 21681168
    PeterTraneus Anderson
    Anonymous  
  • #4 21681169
    Richard Gabric
    Anonymous  
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  • #5 21681170
    Ian Stedman
    Anonymous  
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  • #6 21681171
    inshah khan
    Anonymous  
  • #7 21681172
    neha dubey
    Anonymous  

Topic summary

The discussion addresses how power MOSFETs are driven by gate drivers when the required gate-to-source voltage (Vgs) is high, especially in circuits with high drain voltages (e.g., 200V+). It clarifies that the MOSFET source voltage is not equal to the high drain voltage but typically much lower, often just a few volts, as the source voltage follows the gate voltage in a source follower configuration. Gate drivers output current to charge the MOSFET gate capacitance, with typical output voltages around 10-30V, which is sufficient to achieve the necessary Vgs for switching. For high-side switching with high supply voltages, specialized floating or bootstrap gate driver ICs (e.g., Infineon IR2125, Linear Technology LTC7001) maintain the gate voltage above the source voltage by 10-18V, enabling proper MOSFET turn-on. The UCC20520 gate driver is designed for power converters or H-bridge circuits and may not be suitable for simple high-voltage switching without additional level shifting or floating supplies. Using P-channel MOSFETs or adding level shifting components like resistors and zener diodes can also be solutions depending on the circuit topology. The key is that gate drivers are connected between gate and source, not gate and ground, to ensure the correct Vgs is applied regardless of the high drain voltage.
Summary generated by the language model.
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