PWM controllers for communications infrastructure
National Semiconductor
LM5045 and LM5046 PWM controllers
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.
More stories
2A RGB LED driver for portable projectors
National Semiconductor has introduced a 2A red, green and blue (RGB) LED driver for portable projectors that drives three common anode RGB high-brightness LEDs sequentially with a single inductor.
Power modules suit systems without airflow
National Semiconductor has introduced three Simple Switcher power modules, designed to drive high output voltage applications in the industrial, communications infrastructure and military markets.
LED driver offers good phase-dimmed performance
National Semiconductor has introduced the LM3450 LED driver, which is claimed to feature the industry's best phase-dimmed performance for high-brightness light-emitting diode (LED) applications.
Buck controller drives high-current telecom apps
National Semiconductor has launched a synchronous voltage-mode buck controller that drives high-current point-of-load applications in printers, telecom, networking and embedded computing.
LED driver has dynamic headroom control
National Semiconductor has announced the industry's first LED driver with dynamic headroom control and multiple outputs for high-power applications that drives up to four strings of LEDs.
