Half-bridge low side and high side gate driver ICsFEATURES AT A GLANCE
|Gate Driver ICs Simplify Design
Lambdaaa’s MOSFET and IGBT gate driver ICs are the simplest, smallest and lowest cost solution to drive MOSFETs or IGBTs up to 1200V in applications up to 12kW, and can save over 30% in part count in a 50% smaller PCB area compared to a discrete opto-coupler or transformer based solution. With the addition of few external components, gate driver ICs provide full driver capability with extremely fast switching speeds, designed-in ruggedness and low-power dissipation.
The gate driver IC’s generate the current and voltage necessary to turn MOSFETs or IGBTs on and off from the logic output of a DSP, micro-controller or other logic device. The input is typically a 3.3 volt logic-level signal. All gate driver ICs are CMOS compatible, and most are TTL compatible. Output currents are up to 2A.
Driving a MOSFET or IGBT in the high side position of a half-bridge topology or 3 phase inverter leg offers the additional challenge that the gate voltage is referenced to the source rather than to ground. The source voltage is a floating point at up to the maximum bus voltage, or voltage rating of the MOSFET or IGBT, 600V and up for motor drive, lighting or SMPS applications. Gate driver uses a patented level shifter technology for high voltage application and offers the only 1200V rating in the industry.
These ICs simplify circuit designs by integrating extensive functionality. They use a low cost bootstrap supply, while opto-coupler-based circuits typically require an auxiliary power supply. Gate Driver ICs offer optional single input or dual input programmable deadtime control for low side and high side drivers as well as for 3 phase drivers to provide design flexibility and allows to minimize cross-conduction. Unique 3-phase drivers allow driving a 3 phase inverter using a single IC.
Gate Driver ICs enable rugged driver designs
Gate Driver ICs are specifically designed with motor drive applications in mind. The newest soft-turn-on limits voltage and current spike and reduce EMI. In addition, they have up to 50V/ns dV/dt immunity and are tolerant to negative voltage transient. The under-voltage lock-out available for most drivers prevents shoot-through currents and device failures during power-up and power-down without any additional circuitry. The output drivers feature a high pulse current buffer stage designed for minimum driver cross-conduction.
Noise immunity is important for the high-side position which has a floating voltage and is susceptible to high noise levels, particularly in motor drive applications. Noise immunity ensures that the MOSFET or IGBT doesn’t turn on accidentally. Noise immunity is obtained by using Schmitt-triggered input with pull-down. Additional noise immunity is obtained with separate logic and ground pins in some ICs, such as the 600V ICs in 14-pin packages.
Gate Driver ICs enable fast switching speeds
Gate Drive ICs have ten times better delay matching performance than opto-coupler-based solutions. Delay matching between the low-side and high-side driver is typically within ± 50ns (and as low as ± 10ns for some specialty products), allowing complete dead-time control for better speed range and torque control in motor drive applications. Fast switching also reduces switching power losses and allows leveraging the full benefits of the fastest IGBTs available on the market today for better torque control over a wider speed range.
Application Note: AN-978: HV Floating MOS-Gate Driver ICs
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