N-channel MOSFET driver

Linear Technology has introduced the LTC4447, a high-speed synchronous MOSFET driver designed to drive upper and lower power N-channel MOSFETs in a synchronous rectified converter topology.

The driver, combined with power MOSFETs and one of the company’s DC/DC controllers, forms a complete synchronous regulator that can be used as a step-down or step-up DC/DC converter.

The device drives both upper and lower MOSFET gates from rail-to-rail over a voltage range of 4 to 6.5 V and operates from a supply voltage up to 38 V. The driver can sink up to 5 A and source up to 3.2 A, making it suitable for driving high gate capacitance, high current MOSFETs.

It can also drive multiple MOSFETs in parallel for higher current applications and it includes an integrated bootstrap Schottky diode. The fast 8 ns rise time, 7 ns fall time of the top MOSFET and 7 ns rise time, 4 ns fall time of the bottom MOSFET, when driving a 3000 pF load, minimising switching losses and improve efficiency.

Adaptive shoot-through protection is integrated to prevent both the upper and lower MOSFETs from conducting simultaneously while minimising dead time.

The device has a three-state PWM input for power stage shutdown that is compatible with single- and multi-phase controllers employing a three-state output feature. In addition, it has a separate supply for the input logic to match the signal swing of the controller IC and undervoltage lockout circuits on both the driver and logic supplies.