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Apr 06, 2017
04:09 AM
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Apr 06, 2017
04:09 AM
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Apr 13, 2017
05:19 PM
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Apr 13, 2017
05:19 PM
The below diagram available in CoolMOS™ device datasheet shows the typical variation of the requisite gate charge at the given gate-source and drain-source voltages for turning on a Mosfet with the specified current.
The gate charge comprises the charge QGS, which is required for charging the gate-source capacitance CGS. During this phase, after the gate threshold voltage VGS(th) has been reached, the drain current rises to its specified value, and the drain-source voltage then falls. But until this voltage VDS has fallen to its actual residual value, the gate-drain capacitance (Miller capacitance) has to be discharged. This charge component is defined as the gate-drain charge QGD. The charge Total Gate charge QG = QGS + QGD is not sufficient fully to turn on the transistor since the residual voltage and the drain-source turn-on resistance have not yet been minimized. Only with a charge corresponding to a gate-source voltage of VGS = 10 V are turn-on resistance, and thus static losses, optimized. This whole charge QGtot or total gate charge depends on the drain-source voltage that has to be switched; the magnitude of the drain current that has to be switched has little influence on the requisite overall charge
The gate charge comprises the charge QGS, which is required for charging the gate-source capacitance CGS. During this phase, after the gate threshold voltage VGS(th) has been reached, the drain current rises to its specified value, and the drain-source voltage then falls. But until this voltage VDS has fallen to its actual residual value, the gate-drain capacitance (Miller capacitance) has to be discharged. This charge component is defined as the gate-drain charge QGD. The charge Total Gate charge QG = QGS + QGD is not sufficient fully to turn on the transistor since the residual voltage and the drain-source turn-on resistance have not yet been minimized. Only with a charge corresponding to a gate-source voltage of VGS = 10 V are turn-on resistance, and thus static losses, optimized. This whole charge QGtot or total gate charge depends on the drain-source voltage that has to be switched; the magnitude of the drain current that has to be switched has little influence on the requisite overall charge
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Apr 13, 2017
05:19 PM
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Apr 13, 2017
05:19 PM
The below diagram available in CoolMOS™ device datasheet shows the typical variation of the requisite gate charge at the given gate-source and drain-source voltages for turning on a Mosfet with the specified current.
The gate charge comprises the charge QGS, which is required for charging the gate-source capacitance CGS. During this phase, after the gate threshold voltage VGS(th) has been reached, the drain current rises to its specified value, and the drain-source voltage then falls. But until this voltage VDS has fallen to its actual residual value, the gate-drain capacitance (Miller capacitance) has to be discharged. This charge component is defined as the gate-drain charge QGD. The charge Total Gate charge QG = QGS + QGD is not sufficient fully to turn on the transistor since the residual voltage and the drain-source turn-on resistance have not yet been minimized. Only with a charge corresponding to a gate-source voltage of VGS = 10 V are turn-on resistance, and thus static losses, optimized. This whole charge QGtot or total gate charge depends on the drain-source voltage that has to be switched; the magnitude of the drain current that has to be switched has little influence on the requisite overall charge
The gate charge comprises the charge QGS, which is required for charging the gate-source capacitance CGS. During this phase, after the gate threshold voltage VGS(th) has been reached, the drain current rises to its specified value, and the drain-source voltage then falls. But until this voltage VDS has fallen to its actual residual value, the gate-drain capacitance (Miller capacitance) has to be discharged. This charge component is defined as the gate-drain charge QGD. The charge Total Gate charge QG = QGS + QGD is not sufficient fully to turn on the transistor since the residual voltage and the drain-source turn-on resistance have not yet been minimized. Only with a charge corresponding to a gate-source voltage of VGS = 10 V are turn-on resistance, and thus static losses, optimized. This whole charge QGtot or total gate charge depends on the drain-source voltage that has to be switched; the magnitude of the drain current that has to be switched has little influence on the requisite overall charge