ON Semiconductor Automotive Charger (OBC) Power Solutions

Release time: 2021-09-15


The case details a 3.3KW On Board Charger power solution that combines the ON FAN9672's dual-channel interleaved CCM boost PFC control chip with the FAN7688's advanced secondary-side LLC resonant converter controller with synchronous rectifier control. The FAN9672 integrates a front-end, average current mode, step-up power factor correction circuit with innovative channel management to smoothly load/unload the power from the channel based on the CM pin voltage, improving the PFC converter With a load transient response, the FAN7688 is an advanced pulse frequency modulation (PFM) controller that provides the industry's best isolated DC/DC converter efficiency, including LLC resonant converter with synchronous rectification (SR). It uses charge-controlled current mode control technology in which the oscillator's triangular waveform is combined with integrated switch current information to determine the switching frequency. This provides better power stage control to output transfer, which simplifies the feedback loop design while allowing true input power limiting characteristics. Regardless of the load conditions, the closed-loop soft-start feature helps prevent the error amplifier from saturating and allows for a monotonic rise in the output voltage. Dual edge tracking self-adjusting dead time control minimizes body diode conduction time and therefore maximizes efficiency. The overall plan PF>0.99, Eff.>95, to meet the relevant technical requirements of the OEM for OBC.