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MDmesh II
Second generation HV Power MOSFETs for SMPS and adapters
The continuous requests from the market for higher power density and lower cost in commercial SMPS (Switch Mode Power Supplies) have forced semiconductor manufacturers to push device optimization to the limit.
ST has developed a new Power MOSFET series using MDmesh II technology, which combines the Multiple Drain Mesh vertical structure to ST's Mesh Overlay horizontal layout. This provides an improved efficiency due to inferior conduction losses and low switching losses coupled with a significant space reduction.		 MDmesh II Second generation HV Power MOSFETs for SMPS and adapters

MDmesh II Brings Even Lower RDS(on)
The new Multiple Drain Mesh vertical structure, created thanks to an optimized p-strip array which reduces the total resistivity of the doped drain layer, has delivered an remarkable reduction of the RDS(on) resistance value when compared to the previous MDmesh generation. At the same time a tight control of its temperature dependence is maintained.
MDmesh II Power MOSFETs
Comparison between former and new MDmesh II generation


Minimized FOM And Rg
In this generation, ST`s Mesh Overlay horizontal layout also guarantees a perfect control of the internal gate resistance and intrinsic capacitances with an optimized thickness of the oxide layer.
Although a lower on-resistance is in an important factor on-state losses, it is not the only influential factor.
A reduction of the total losses is also achieved by lower switching losses which are dependent on internal gate resistance and intrinsic capacitances.

A controlled gate internal resistance allows a reduced delay time and in consequence a faster switching time for the new higher efficiency SMPS
design-ins;
Through simpler and cheaper gate drive circuitry, controlled intrinsic capacitances guarantee low crossover time and low gate charge, resulting in remarkable improvements in SMPS efficiency.

MDmesh II Power MOSFETs
Comparable figure of merit RDS(on) x Qg (Typ.) @10V for similar die size

Lower Gate Threshold VGS(th)
A specific characteristic of the second generation MDmesh Power MOSFET is the capability to bear a greater quantity of current at a lower VGS voltage used to drive the device. The range of VGS has changed to give optimized driving with a good noise immunity and the same threshold spread.

VGS
min
typ
max
MDmesh I
3V
4V
5V
MDmesh II
2V
3V
4V

Segment And Applications
With improved diode dv/dt capability, MDmesh technology has permitted the development of a series of new design-in activities in the field of PFC and SMPS systems where it allows safe operation mode in bridge topologies. The new MDmesh high voltage Power MOSFET series has brought stricter specifications of RDS(on), which in turn has led to devices in smaller packages. Board space is no longer wasted by using more large devices, in parallel to reach the same on-resistance.
Moreover, the improvement in efficiency given by the new MDmesh MOSFET series is obtained at high operating frequencies and is coupled to lower temperatures that allow significant equipment size reduction with smaller magnetic components and smaller heat sinks. The association of these factors results in an improved system reliability and a substantial cost reduction.

MDmesh II
PFC utilizing the L6562 controller and two STP12NM50 in parallel as power switches. It handles a power of 375W. The circuit shows one STP25NM50N replacing two STP12NM50 belonging to the previous MDmesh technology

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