Buck converter

Fairchild Semiconductor has introduced a synchronous buck converter chip set designed specifically to optimize efficiency and space in notebooks.


Fairchild Semiconductor has introduced a synchronous buck converter chip set designed specifically to optimize efficiency and space in notebooks using the latest IMVP (Intel Mobile Voltage Positioning) specifications.


The chip set comprises the high-side “control” MOSFET ( FDS6298) and the low-side “synchronous” MOSFET ( FDS6299S).


The FDS6299S device’s monolithic SyncFET technology eliminates the need for an external Schottky diode, resulting in board space savings and reduced assembly costs.


This integrated chip set features a very low Qgd or “Miller” charge for fast switching speeds as well as a Qgd / Qgs ratio of less than 1 to limit the potential for cross conduction losses. In addition to Vcore designs, the fast-switching FDS6298 and the low RDS(on) FDS6299S offer benefits as a matched pair that are suited for high current point-of-load (POL) converters in such applications as high-end communications equipment.


Key performance characteristics of the FDS6298 (high-side) MOSFET include:



  • Low total Qg (9nC @ VGS=4.5V) and Qgd (3nC @ VGS=4.5V) for fast-switching speeds to increase efficiency;
  • Optimized die and lead frame design to reduce package resistance and inductance, reducing conduction and source terminal inductance switching losses; and
  • Rg-specified and 100% Rg-tested resulting in a well-defined drain-source switching characteristic.

Key performance characteristics of the FDS6299S (low-side) MOSFET include:



  • Low RDS(on) (3.9mOhm (max) @ VGS = 10V) to reduce DC losses;
  • Low body diode loss (low QRR and low forward voltage drop) to improve efficiency;
  • Soft-recovery characteristic to lower noise, and low Crss to reduce the potential for cross conduction; and
  • Low total Qg (31nC @ VGS=5V) for reducing gate drive requirements.

The products are available in a lead (Pb)-free SO-8 package that meets or exceeds the requirements of the joint IPC/JEDEC standard J-STD-020B and are compliant with the European Union requirements now in effect.


Details of the products can be found online at:


www.fairchildsemi.com/ds/FD/FDS6298.pdf


www.fairchildsemi.com/ds/FD/FDS6299S.pdf