One of the main obstacles in using IGBTs in low power bridge applications is the need for the freewheeling diode: the much higher inherent current density of IGBTs cannot be compensated by the extra cost of a separate diode that is free with Power MOSFETs. The double die assembly, IGBT plus antiparallel diode in the same package, can only satisfy the need for space saving and not the cost. ST by offering the
STGD3NB60SD, a 3A / 600V IGBT with its unique integrated freewheeling diode, has overcome this drawback and offers customers a cost effective and more compact solution. The well proven PowerMESH layout, an optimized epitaxial process and the proprietary SIPS edge termination give to the
STGD3NB60SD unrivalled on-losses (typical VCEsat=1.1V @ 3A) and optimal diode performances.
A high frequency step-up converter, using an “NB” series Power MOSFET, generates a voltage of about 100V. The following inverter must supply to the lamp a highly symmetrical ac voltage at low frequency and a nominal power of 35W. Switches with 600V breakdown voltage capability working at 450Hz are required. As a consequence this implies that the on-losses in the power switches have to be minimized. Current solutions adopt 0.75Ohm Power MOSFETs like STB9NB60, or IGBTs in DPAK or D²PAK with the antiparallel freewheeling diode. The inverter also has to manage the peak power for rapid turn-on of the l the most critical power losses are when the inverter switches around two Amps. As a figure of merit therefore, the voltage drop at an output current of 2A can be chosen to evaluate the on-losses in the inverter as illustrated in the table below.