Product Details Supplier Info More products

National Semiconductor has introduced what are claimed to be the industry’s first full-bridge pulse width modulation controllers to integrate all four primary-side 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.

The controllers will be showcased at the Applied Power Electronics Conference and Expo (APEC) in Texas on 6-10 March.

The LM5045 and LM5046 pulse width modulation (PWM) controllers belong to National Semiconductor’s Powerwise energy-efficient product portfolio.

They are said to 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 PWM controller contains all of 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 (ZVS) to minimise electro-magnetic interference (EMI) due to switching noise, the LM5046 PWM controller contains all the features necessary to implement a phase-shifted full-bridge topology.

Offered in small, thermally enhanced 5.0 x 5.0 x 0.8mm LLP and 4.4 x 9.7 x 0.9mm TSSOP packages, the full-bridge controllers operate on the primary side of an isolated DC/DC converter with input voltage up to 100V.

These integrated controllers provide robust 2A 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 (SR) allows monotonic turn-on of the power converter, even with pre-bias load conditions.

The synchronous rectifier control signals offer independent and programmable leading/trailing edge dead-times between the primary and secondary MOSFET control signals for optimising efficiency, and the SR signals are limited to 5V for use with digital isolators.

Additional features include dual-mode over-current protection featuring both cycle-by-cycle current limiting and hiccup mode restart, programmable soft-start, timing for both primary and synchronous rectifiers, programmable line UVLO and OVP, a synchronisable 2MHz oscillator and thermal shutdown.

National Semiconductor’s LM5045 and LM5046, together with secondary side FET drivers such as the LM5110, LM5111 and LM5112, provide a complete controller solution to implement an efficient, small form-factor, full-bridge power converter.

National’s full-bridge PWM controllers are offered in 28-pin LLP and thermally enhanced TSSOP packages.

National Semiconductor

View full profile