LMS1225

The LMS1225 device is an industry-first 22.5V, synchronous-rectification power stage with an integrated gate driver and a MOSFET. The device provides body-diode conduction sensing and reporting and integrates a high performance driver that allows any digital PWM controller to achieve advanced synchronous-rectification (SR) control. The device contains a high-speed gate driver, a body-diode conduction-sensing circuit, an autonomous turn-on and dead time reporting features. The device is designed for high-efficiency center-tapped LLC applications, where SR dead-time optimization is desired.

The LMS1225 device offers efficient operation at high frequencies up to 5MHz. The gate drive control turns on through PWM signal in standard operation or autonomously turns on in IDM operation. In IDM operation an internal high-speed comparator with a –250mV threshold detects the body-diode conduction and autonomously switches on the MOSFET at the turn-on edge if the PWM signal is already high. The device is capable of sensing body-diode conduction time as low as 4ns. In both operation modes, turn-off control relies on PWM falling edge.

The LMS1225 internal high-speed comparator with a –250mV threshold detects the body-diode conduction and reports the information to the digital-power controller through the DTC pin. The device senses body-diode conduction time as low as 4ns. The SR turn-on and turn-off edge is optimized by the digital-power controller which analyzes the body-diode conduction information reported by the LMS1225 DTC pin.

The benefits of the chipset include maximizing system efficiency by minimizing body-diode conduction time, robust and fast bi-directional current sensing. The integrated approach promotes high power density with a layout which is optimized by as much as 30% in comparison to discrete solutions.