100-GbE/OTN VSR28 to CAUI Gearbox

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100 Gb/s "gearbox" PHY that multiplexes and demultiplexes four 25 Gb/s channels to/from ten 10 Gb/s channels supporting Ethernet and Optical Transport Networking (OTN).
The BCM84790 is compliant with the IEEE 802.3ba standard for 100 GbE and ITU OTL 4.4 signalling as well as 40 GbE, OTL 3.4 and OTL 4.10. The line interface supports four bidirectional lanes at 25.78125/27.952493 Gb/s for 100 GbE/OTL4.4 applications. It can also be configured to support four bidirectional lanes at 10.3125 to 11.18 Gb/s for 40G repeater applications. The system interface only supports 10 bidirectional lanes or four bidirectional lanes at 10.3125 to 11.18 Gb/s.


  • Full-duplex 10 lane to four lane gearbox via IEEE 802.3ba Clause 83 PMA (CAUI to VSR28)
  • Full-duplex 10 lane to four lane gearbox via ITU OTL4.4 (CAUI to VSR28)
  • Full-duplex four lanes to four lanes at 10.3125 to 11.18 Gb/s (XLAUI to XLPPI)
  • Transmit Pre-Emphasis and Adaptive receive equalization on all data I/O
  • High-speed Optical Duo-binary (ODB) Precoder and Decoder
  • Integrated CAUI input AC Capacitors


  • Blade Servers
  • DWDM Long Haul Transport
  • DWDM Metro Transport
  • Enterprise LAN Switching

Lifecycle Status


Specification Value
Lifecycle Active
Distrib. Inventory No
Package 27x27 mm
PHY Type Gearbox
I/O Controller
Bus Interface
Transfer Rates
External Memory Interfaces 8-bit and 16-bit Flash, w/ 6 Chip Selects SRAM, NVSRAM
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