| A ‘Dangerous’ Stress Condition |
If the Power MOSFET driving is not properly arranged, diode recovery dv/dt is very often the reason for ballast failures, especially during sudden frequency changes in the bridge caused by:
 |
Start-up of the tube |
|
Tube removal |
|
End of life |
The Power MOSFET may be destroyed by simultaneous stresses such as high drain current, high drain source voltage during the diode recovery. |
| |
Body diode dv/dt and di/dt crossing during recovery phase
|
| SuperFREDmesh Product Family |
For those cases where it is not possible to maintain low rates of dv/dt, the choice for Power MOSFETs with higher capability is mandatory.
ST has recently enhanced its standard SuperMESH product family by adding a new series that includes a fast recovery body diode: SuperFREDMesh. This product series, obtained with a new carrier lifetime control technique, besides the well known low Qrr and trr, offers an outstanding dv/dt capability of 15V/ns.
All the features mentioned are the exact requirements of lighting applications such as electronic ballasts and High Intensity Discharge Lamps, without renouncing to the traditional cost competitiveness of the SuperMESH family. |
| New SuperFREDmesh Devices |
|
Part number |
BVDSS
[V] |
RDS(on)
[Ohm] |
dv/dt
[ns] |
Package |
|
|
500 |
2.7 |
15 |
TO-220 |
|
520 |
1.5 |
15 |
TO-220 |
|
600 |
0.95 |
15 |
TO-220 |
|
|
|
