03-08-2015 | Premo | Design Applications
Embedded AC/DC and DC-DC converters represent a growing technology in the automotive marketplace. For EV and HEV cars that become to be produced at huge volumes, both onboard battery chargers and 14V power supplies are required to ensure the transfer of energy from the 50/60Hz mains when charging to the final equipments used during a drive (ECUs, radio-GPS systems, lightning etc.). The related power electronics involves not only transformers and filtering chokes built in half- or full-bridge topologies but also semiconductors like IGBTs or MOSFETs that have to be accurately commanded to deliver the expected output voltage while perturbations at the input or load can affect the global performances. The control-loop often requires a good insulation between the primary side connected to the HV DC-bus (typically 350-800V) and the gate of the transistors (10-15V). In response, Premo has developed a new high isolated gate-drive transformer for such applications. The GDAU targets applications where a low-size insulated SMD transformer is required to control the MOS transistors. This less than 8mm height device guarantees an insulation level of 3kV and a creepage distance greater than 5mm. The use of special insulated wire and special construction lower the parasitic elements to values (the leakage inductance is 2µH max whereas the prim-sec stray capacitance is less than 12pF) fully optimized for a switching frequency in the 90-125kHz range. The GDAU-001 reference provides a 1:1+1 turn-ratio that can command 2 transistors of the same polarity at once. It can withstand 150Vus without any noticeable saturation (15V control at 100kHz for example). The GDAU series shows a magnetizing inductance value of no less than 400µH to prevent the output control voltage from any noticeable droop. The low DC resistance values of the windings ensure its capability to drive currents up to 0.5Arms continuous without overheating. GDAU series is a SMD technology delivered in Tape&Reel packaging for easy Pick&Place assembling process. Moreover it is fully compliant with most of the RoHS lead-free reflow soldering techniques. This technology is 100% compatible with AOI (Automatic Optical Inspection) system for final assembled PCB control. GDAU series is a design fully compliant with the automotive AEC-Q200 standard. It has been validated in operation from -40C to +155C. With only UL94V-0 listed insulating materials and a total weight of less than 5g, the component shows no thermal aging effect on this wide operating temperature range, says the company.
