National Semiconductor LM5045 and LM5046 full-bridge PWM controllers

National Semiconductor has introduced what it claims is the first full-bridge pulse width modulation controllers to integrate all four primary-side bridge MOSFET gate drivers.

The LM5045 and LM5046 are suitable for delivering higher efficiency and higher power density in quarter-brick and eighth-brick power modules used in a variety of high-input voltage communications infrastructure applications.

Members of the company’s PowerWise energy-efficient product family, the controllers ease the design of full-bridge topology-based power converters into small form factor power supplies by reducing the number of external power components needed with existing full-bridge solutions.

The LM5045 contains all the features necessary to implement a conventional full-bridge topology power converter using either current mode or voltage mode control.

For applications requiring zero-voltage switching to minimise electro-magnetic interference due to switching noise, the LM5046 PWM controller contains all the features necessary to implement a phase-shifted full-bridge topology.

The controllers operate on the primary side of an isolated DC-DC converter with input voltage up to 100 V, providing 2 A high- and low-side gate drivers for the four external bridge MOSFETs in addition to the control signals for the secondary side synchronous rectifier MOSFETs and an internal high-voltage start-up regulator.

Intelligent start-up of the synchronous rectifiers allows monotonic turn-on of the power converter, even with pre-bias load conditions.