Gate drivers play key role in SMPS and inverter designs
 Today’s power conversion and power management applications demand compact yet robust power switching circuitry that supports high-voltage, high-frequency operation with the minimum of losses from the smallest possible PCB area.
The choice of MOSFET technology has a significant impact on how successfully this demand can be addressed. However, the best performance will only be achieved through carefully combining the chosen MOSFETs with other components. And among the most important tasks facing the designer is identifying MOSFET gate driver ICs that are optimised for the target application.
Power conversion requirementsThe design of modern power switching applications such as switched-mode power supplies (SMPS), DC-to-DC converters, industrial motor drives and solar panel inverters that convert voltages from a photovoltaic cell are driven by a variety of factors.
There are commercial, legislative and environmental pressures to improve efficiency and drive down losses so as to reduce operational costs and minimise both energy use and harmful greenhouse gas emissions. There are end-user demands for constantly improved performance without any increase in product or system size, and there is the need to build in safeguards that protect both users and critical components.
At the same time, high component densities put pressure on real estate and the need to effectively manage thermal performance, while budget constraints demand the smallest possible bill of materials (BOM) and the use of less costly components. Finally, all of this must typically be achieved with the shortest possible time between development and final production.
It is these factors that have led to a significant growth in the use of high-current, high-speed switching power conversion circuits. Increased switching speeds not only contribute to improved performance and efficiency but also have the significant advantage that they allow the use of smaller and less costly inductive components for filtering. Such circuits will typically be built around controller or regulator ICs that provide the requisite high-frequency input signal and power MOSFETs that physically switch the load.
Driving superjunction MOSFETsAchieving the switching and efficiency performance demanded by modern power conversion applications demands high-performance MOSFETs and this typically means devices based on superjunction (SJ) semiconductor processes. This is because SJ MOSFETs employ a drain structure that supports much lower area-specific on-state resistance (RDS(ON)A) without compromising the requisite voltage-blocking capabilities. Together with several cell geometry considerations SJ technology also reduces all device capacitances, thus improving the switching-related figures of merit (FoM) and other application performance characteristics.
Fig. 1 shows a schematic of the latest evolution of SJ technology – CoolMOS C7 – in which a seven-column, high-aspect ratio compensation structure has been deployed. The significant performance improvements that this structure offers can be seen in the latest CoolMOS C7 600V series, which are the first MOSFETs to break the 1Ω per mm2 RDS(ON)A limit.
There are many cases where it is not practical for the controller IC to directly drive the chosen MOSFET, not least that many controllers simply don’t have a high enough output capability for today’s high-performance power devices.
SJ MOSFETs, for example, typically require a gate source voltage (Vgs) of at least 8V. At the same time, high-efficiency demands fast-switching transients and high currents, typically in excess of 1Apeak. As a result it is neither technically (thanks largely to heat dissipation issues) or commercially viable to monolithically integrate the driver circuitry into the controller IC.
In addition, a designer may wish to mitigate potential EMI problems caused by high-speed switching by ensuring that the drive circuitry is as close to the load as possible.

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Gate drivers play key role in SMPS and inverter designs
 Today’s power conversion and power management applications demand compact yet robust power switching circuitry that supports high-voltage, high-frequency operation with the minimum of losses from the smallest possible PCB area.
The choice of MOSFET technology has a significant impact on how successfully this demand can be addressed. However, the best performance will only be achieved through carefully combining the chosen MOSFETs with other components. And among the most important tasks facing the designer is identifying MOSFET gate driver ICs that are optimised for the target application.
Power conversion requirementsThe design of modern power switching applications such as switched-mode power supplies (SMPS), DC-to-DC converters, industrial motor drives and solar panel inverters that convert voltages from a photovoltaic cell are driven by a variety of factors.
There are commercial, legislative and environmental pressures to improve efficiency and drive down losses so as to reduce operational costs and minimise both energy use and harmful greenhouse gas emissions. There are end-user demands for constantly improved performance without any increase in product or system size, and there is the need to build in safeguards that protect both users and critical components.
At the same time, high component densities put pressure on real estate and the need to effectively manage thermal performance, while budget constraints demand the smallest possible bill of materials (BOM) and the use of less costly components. Finally, all of this must typically be achieved with the shortest possible time between development and final production.
It is these factors that have led to a significant growth in the use of high-current, high-speed switching power conversion circuits. Increased switching speeds not only contribute to improved performance and efficiency but also have the significant advantage that they allow the use of smaller and less costly inductive components for filtering. Such circuits will typically be built around controller or regulator ICs that provide the requisite high-frequency input signal and power MOSFETs that physically switch the load.
Driving superjunction MOSFETsAchieving the switching and efficiency performance demanded by modern power conversion applications demands high-performance MOSFETs and this typically means devices based on superjunction (SJ) semiconductor processes. This is because SJ MOSFETs employ a drain structure that supports much lower area-specific on-state resistance (RDS(ON)A) without compromising the requisite voltage-blocking capabilities. Together with several cell geometry considerations SJ technology also reduces all device capacitances, thus improving the switching-related figures of merit (FoM) and other application performance characteristics.
Fig. 1 shows a schematic of the latest evolution of SJ technology – CoolMOS C7 – in which a seven-column, high-aspect ratio compensation structure has been deployed. The significant performance improvements that this structure offers can be seen in the latest CoolMOS C7 600V series, which are the first MOSFETs to break the 1Ω per mm2 RDS(ON)A limit.
There are many cases where it is not practical for the controller IC to directly drive the chosen MOSFET, not least that many controllers simply don’t have a high enough output capability for today’s high-performance power devices.
SJ MOSFETs, for example, typically require a gate source voltage (Vgs) of at least 8V. At the same time, high-efficiency demands fast-switching transients and high currents, typically in excess of 1Apeak. As a result it is neither technically (thanks largely to heat dissipation issues) or commercially viable to monolithically integrate the driver circuitry into the controller IC.
In addition, a designer may wish to mitigate potential EMI problems caused by high-speed switching by ensuring that the drive circuitry is as close to the load as possible.

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