The higher power supply efficiency of the RJK0383DPA has two important benefits. It uses a small WPAK3 package that reduces the chip mounting area to about half that of a dual-package power MOSFET configuration, offering the same level of power supply efficiency. It also allows the device to deliver more output current. Smaller synchronous-rectification DC/DC converters are thus enabled, facilitating the higher mounting densities eagerly sought in mobile devices and other products in which small size adds convenience.
Evolution of solutions for improved synchronous-rectification DC/DC converters
Multiple synchronous-rectification DC/DC converters have become necessary in many types of electronic products. One of the main reasons for this is because the power consumption of successive generations of individual microchips has increased in recent years due to greater functionality, higher performance and the need to handle greater volumes of data. This led to demand for synchronous-rectification DC/DC converters specified for lower voltages and higher currents. But problems surfaced as the number of power MOSFETs used in a single system increased, so Renesas boosted the performance and improved the packages of its power MOSFET products.
“A two-package configuration made it possible to raise the power-supply efficiency of synchronous-rectification DC/DC converters so the output current could be increased without adding more power MOSFETs,” said Tetsuo Sato, director, solutions business unit, Renesas Technology America. “On the other hand, dual-type products that integrate two power MOSFETs in a single package have the advantage of having a smaller mounting area. However, the power-supply efficiency of these dual-type products was not as good as that of two-package configurations, so their maximum output current was lower. The market clearly desired a dual-type power MOSFET product with improved power supply efficiency and more output current to meet the space limitations of mobile devices. The new RJK0383DPA device directly addresses this need.”
The high-side power MOSFET in the RJK0383DPA has a drain-gate load (Qgd) of only 1.5nC (at VDD=10V) for a fast switching speed and correspondingly high efficiency. The device’s low-side power MOSFET has a low on-resistance3 (RDS (on)) of 3.7mΩ (typical, at 4.5V) that reduces power loss. Additionally, the device integrates a Schottky barrier diode (SBD) that is connected via low-inductance wiring to the low-side power MOSFET. This design speeds up the switching of current flow to the SBD during the DC/DC converter’s dead time, for less power loss. It also suppresses voltage spikes during switching, thereby reducing noise.
The advanced semiconductor manufacturing process that Renesas uses to fabricate the RJK0383DPA achieves lower loss and higher efficiency than the previous ninth-generation process. On-resistance4 is about 30 percent lower, while the opposing characteristics of gate charge capacitance (Qg) and drain-gate load (Qgd) are approximately 27 percent and 30 percent lower, respectively. (Both improvements are relative to earlier power MOSFET products with the same on-resistance.)
Besides the RJK0383DPA, Renesas is developing two other dual-type power MOSFETs having different output current ratings, the RJK0384DPA and RJK0389DPA. Further into the future, more products suitable for other DC/DC converter power supply specifications are under development in response to the needs of the market.
Price and Availability
|Product Name||Package||Sample Price / Availability|
dual-type power MOSFET
(Renesas package code)
|$0.89 / Q4 2008|