MOSFET Drivers Offer Flexible Gate-drive Levels

Jan 3, 2006 5:28 PM

Vishay has released three new high-speed, half-bridge MOSFET driver ICs that provide flexible gate drive levels to optimize efficiency, reduce component count, and minimize expense in high-frequency, high-current dc-dc synchronous rectifier buck power supplies.

The new MOSFET drivers operate with external n-channel MOSFETs. They are designed to provide gate drive voltages of 8 V or 12 V, operate at switching frequencies up to 1 MHz and function in 5-V to 48-V systems, including power converters and industrial and computing equipment. The high-side driver of each device has an internal bootstrap diode to reduce external component count.

In the SiP41109, the gate drive voltage is supplied to the high-side driver by an integrated 80-mA, 8-V regulator and to the low-side driver by the supply voltage. In the SiP41110, the regulator supplies both high-side and low-side voltages. In this way, designers can choose the gate drive voltage most suitable for achieving an optimal trade-off between MOSFET conduction and switching loss for the chosen operating frequency.

Adaptive shoot-through protection in the drivers prevents simultaneous conduction of the external MOSFETs. Undervoltage lockout holds off operation of the circuits until their supply voltages reach valid operating levels, and overtemperature protection disables the drivers if the die temperature exceeds 165°C.

The SiP41108 provides several additional features, including an adjustable high-side propagation delay, a dedicated shutdown pin and a synchronous MOSFET disable function for improved efficiency under certain operating conditions. The SiP41108 is packaged in the lead (Pb)-free PowerPAK TSSOP-16.

The SiP41109 and SiP41110 are packaged in the lead (Pb)-free SOIC-8 and use the same pin-out as the popular HiP6601 and HiP6603 while delivering a 4X times higher operating voltage of 48 V and a better than 2X higher gate drive current. As a result, designers can use the new devices to upgrade the voltage and current density of their devices without necessitating a board redesign.

Both the SiP41109 and SiP41110 provide a 3-state PWM input, which also provides for output shutdown. They enter shutdown mode when the PWM signal enters the tri-state window and remains within the shutdown window for more than 240 ns. If the PWM pin is left open, the pin is held to 2.5 V by an internal voltage divider, which forces the 3-state condition.

Samples and production quantities are available now, with lead times of seven weeks for larger orders. Pricing in 1000-piece quantities is $0.85 for the SiP41109 and SiP41110 and $0.90 for the SiP41108.

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