Irvine-based Microsemi, a manufacturer of analog and mixed signal semiconductors, said today that it is in an agreement to purchase Israel-based PowerDsine Ltd. PowerDsine develops power-over-Ethernet products. The deal is worth $245M in a combined cash and stock deal. Power-over-Ethernet products are used for powering network devices, including WLAN access points, VoIP phones, and remote security cameras without requiring additional A/C connections. POwerDsine has approximately 136 employees worldwide. Miscrosemi was advised by Thomas Weisel Partners. PowerDsine was advised by Citigroup in the deal.