Octal Integrated IEEE 802.3bt-Compliant PSE Controller

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The Broadcom® BCM59121 is a highly integrated IEEE 802.3bt-compliant power sourcing equipment (PSE) controller with unsurpassed integration and flexibility. It contains eight low-RDS (0.2Ω), high- voltage pass-FETs, each with a very accurate, lossless, proprietary internal current sense and an onboard microcontroller, all targeted to significantly reduce the complexity of Power over Ethernet (PoE) and Power over Ethernet Plus (PoE+) and UPoE designs while easing PCB layout. The BCM59121 provides excellent protection under all possible fault conditions and overloads. It also supports two-event Classification for Type 2 (30W) applications and multi-event Classification for 802.3bt Standard Type3 applications.
The BCM59121 has a networking-oriented host interface, communicating via a BSC bus and capable of speeds up to 2.4 Mb/s


  • IEEE 802.3bt-compliant with support for IEEE 802.3at and IEEE 802.3af
  • Supports multi-event classification (Type 2 and Type 3)
  • Supports four-pair 60W bt Type3 (BCM59121) applications
  • Supports detection of legacy power devices (PDs)
  • Cascading of multiple devices; up to 64 ports supported
  • Programmable ICUT and ILIM for Type 1, Type 2 and Type 3
  • Broadcom Serial Control (BSC), an NXP I2C-compatible bus architecture
  • Manual/semi-autonomous operating mode
  • Real-time current, voltage, and temperature measurements available per port
  • Overtemperature protection (warning and shutdown)
  • Operates from a 48V supply (nominal) and external 3.3V supply
  • Firmware download capability via BSC communication bus from host
  • 8 mm × 8 mm × 0.9 mm QFN-56 package (0.5 mm pitch) with exposed pad


  • Routers and switches for SMB, enterprise, SOHO, and commercial markets
  • POE Lighting

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