APEC—Day 1

March 06, 2011 by Jeff Shepard

The Applied Power Electronics Conference in Fort Worth, Texas kicked off with new product announcements from major companies in the power electronics industry.

National Semiconductor Corp. introduced what it says is the industry’s first full-bridge pulse width modulation (PWM) controllers to integrate all four primary-side bridge MOSFET gate drivers. The LM5045 and LM5046 are well-suited 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 National’s PowerWise® energy-efficient product family, the LM5045 and LM5046 PWM 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 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 minimize 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 by 5.0 by 0.8mm LLP and 4.4 by 9.7 by 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 highly 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 startup 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 optimizing efficiency, and the SR signals are limited to 5V for use with digital isolators.

Analog Devices, Inc. (ADI) is demonstrating the industry’s first digital PFC (power factor correction) controller with highly accurate AC power meter capability and inrush control functionality. ADI’s new ADP1047 digital PFC controller is effective for ac-dc power-factor correction and precision power metering applications that require high reliability and redundant power supplies, such as communications infrastructure and motor control.

ADI’s new ADP1047 digital PFC controller uses conventional, continuous-conduction mode PFC techniques; all signals are converted to the digital domain, allowing all parameters to be adjusted and reported over a PMBus™ compliant interface--including accurate RMS measurement of input voltage, current and power. This allows designers to optimize system harmonic performance, maximize efficiency across the load range and reduce time-to-market. The ADP1047 is programmed using an intuitive, easy-to-use GUI (graphical-user interface).

"The ADP1047 digital PFC controller is extremely versatile and easy to use, which enables designers to optimize their systems without the complex code programming required by alternative DSP (digital signal processor)-based devices," said Laurence McGarry, marketing manager, Power Management Products Group, Analog Devices. "The ADP1047’s combination of a flexible, digitally controlled PFC engine and accurate input power metering, simplifies and accelerates the adoption of intelligent power management systems."

Exar Corp. added a significant new controller to its PowerXR family of programmable power system ICs. The XRP7724 is a highly integrated programmable power controller with the industry’s most advanced design capabilities, robust performance and the most flexible design environment in the industry. With expanded voltage and current ranges, SMBus compliant I2C interface, and independently controlled channel frequencies, the XRP7724 is flexible enough to handle the most demanding applications spanning mobile to industrial to high-performance computing. Our patented Digital Pulse Frequency Modulation (DPFM) technology lowers standby current enabling system designers to meet strict green power requirements.

PowerXR ICs integrate the best of both worlds; the low cost and flexibility of digital power control as well as the robust power capabilities of high performance analog power switchers. PowerXR products reduce development time from weeks to hours enabling a significant time-to-market advantage for system design engineers. Using the PowerArchitect™ design tool, engineers can easily modify voltage, current, GPIO or other parameters in seconds. Engineers can tweak design parameters throughout the design cycle, qualification into final test, and even when deployed in the field.

The XRP7724 offers a wide input voltage range (4.75 to 25V), and output range (0.6 to 5.1V), with a built-in Low-Dropout regulator (LDO) for standby power, power sequencing capability, and integrated gate drivers. These power system ICs contain patented Digital Pulse Frequency Modulator (DPFM) with ultrasonic mode. The ICs contain an integrated LDO regulator that provides a fifth voltage supply, which can also be employed as a standby-voltage source. The devices contain integrated gate drivers for the switching outputs and up to six General Purpose Input/Output (GPIO) pins. Exar’s PowerArchitect™ software design tool enables designers to intelligently configure the power supply’s voltage setting and current thresholds, fault monitoring and response, soft start and active shutdown timing, and channel sequencing, phase shift management, and loop response, amongst other features. The ICs use a digital PID (proportional, integral, differential) control algorithm that performs full-digital loop control at switching frequencies to 1.2 MHz.