Electromagnetic interference (EMI) is an inevitable issue in power electronics applications. Although many kinds of solutions have been presented to attenuate EMI noise, there is still little research about the EMI suppression scheme utilized in multimode primary-side regulation (PSR) flyback converters. Targeting EMI regulation in multimode PSR flyback converter, a combo EMI suppression scheme comprised of frequency modulation and dual-slope gate driver is adopted to meet stringent EMI requirements, simplifying peripheral components and design of EMI filter. The proposed scheme is implemented in$0.18~\mu $m 5/40 V BCD process and occupies a die size (with pads) of$1.05\times 0.8$mm2. The experimental results show that the conducted EMI waveforms with line/neutral polarity can easily comply with regulations. The deviations of the output voltage are within ±1.3% under different inputs and loads while the peak effciency of 90% is achieved.

The power over Ethernet (PoE) technology has gained intensive attention in networking market owing to the advantages of compactness, flexibility, and cost in application. The automatic maintain power signature (MPS) function specified by IEEE standard extracts the periodic pulsed current to enable applications requiring low power modes. However, a large driving capacity is required due to a large MPS current above 10 mA, sacrificing a certain area. This brief proposes an adaptive MPS scheme, which reuses existing class regulator and delay timer to source a pulsed MPS current to meet the MPS requirements, saving an area of 0.0104 mm2. The proposed MPS scheme has been fabricated in 0.18-$\mu $m 120-V BCD process and the area is$1.37\times 1.00$mm2. The experimental results show that the proposed PoE interface draws a pulsed current with a period of 312 ms and 25.6% duty cycle to address the issue of MPS absence in very low-power standby modes.