National Semiconductor expands its PowerWise family. The new LM5045 PWM controller contains all of the features necessary to implement Full-Bridge topology power converters using either current mode or voltage mode control. This device is intended to operate on the primary side of an isolated dc-dc converter with input voltage up to 100V. This highly integrated controller-driver provides dual 2A high and low side gate drivers for the four external brige MOSFETs plus control signals for the secondary side synchronous rectifier MOSFETs. External resistors program the leading and trailing edge dead-time between the main and synchronous rectifier control signals. Intelligent startup of the synchronous rectifiers allows monotonic turn-on of the power converter even with pre-bias load conditions. Additional features include cycle-by-cycle current limiting, hiccup mode restart, programmable soft-start, synchronous rectifier soft-start and a 2 MHz capable oscillator with synchronization capability and thermal shutdown.
Features
- Highest Integration Controller for Small Form Factor, High Density Power Converters
- High Voltage Start-up Regulator
- Intelligent Sync Rectifier Start-up Allows Linear Turn-on into Pre-biased Loads
- Synchronous Rectifiers Disabled in UVLO mode and Hiccup Mode
- Two Independent, Programmable Synchronous Rectifier dead-time Adjustments
- Four High Current 2A Bridge Gate Drivers
- Wide-Bandwidth Opto-coupler Interface
- Configurable for either Current Mode or Voltage Mode Control
- Dual-mode Over-Current Protection
- Resistor Programmed 2MHz Oscillator
- Programmable Line UVLO and OVP
Typical LM5045 application circuit:
