STMicroelectronics' New Power MOSFET Technology Enables Higher Frequencies and Lower Losses in DC/DC Supplies
Using STMicroelectronics' (ST) latest version of STripFET technology, the company's two new power MOSFETs intended for the most demanding DC/DC converter applications deliver extremely low conduction and switching losses—up to 3W lower in a typical voltage regulator module—and achieve the lowest figure of merit (FOM = Rds(on) x Gate Charge (Qg)) among comparable competitive devices.In addition to the high efficiency, ST's new MOSFETs allow practical circuits to operate at higher-than-normal switching frequencies, enabling a reduction in the size of the circuit's passive components. For example, a 10 percent increase in switching frequency can lead to a 10 percent reduction in passive components required by the output filter.
The STD60N3LH5 and STD85N3LH5 are the first in a new series of STripFET V devices which provide increased efficiency as a result of low ON-resistance and significantly lower total gate charge. Both are 30V (BVDSS) devices, with gate charge (Qg) of just 8.8nC, and Rds(on) of 7.2m¦¸ at 10V.
The STD60N3LH5 is an ideal choice as a control FET in non-isolated DC-DC step-down converters.
The 4.2m¦¸ Rds(on) at 10V of the STD85N3LH5, with a Qg of 14nC, meanwhile, makes it an optimal choice as a synchronous FET. Both devices are produced in DPAK and IPAK packages and will be soon available in other package options including SO-8, PowerFLAT 3.3x3.3, PowerFLAT 6x5, and PolarPAK.
ST's STripFET technology makes use of very high "equivalent cell density" and smaller cell features to achieve extremely low ON-resistance and losses, while using less silicon area. STripFET V is the latest generation of this technology, achieving approximately 35 percent improvement in the critical indicator of silicon resistance and active area, plus some 25 percent reduction in total gate charge per active area, compared to the earlier generation.