100Base-FX (SFP) 操作应使用哪个 Ethernet PHY？

对于新设计，我主要推荐 Texas Instruments DP83822。它采用 5x5mm QFN 封装，提供 RMII、MII 甚至 RGMII 接口连接到微控制器或其他 Ethernet MAC。

确保选择 DP83822xF -F 表示光纤！

由于撰写本文时，DP83822 存在供应短缺，以下替代方案可用于 100Base-FX 操作：

• DP83869HM is a Gigabit Ethernet transceiver that supports 100Base-FX but does not support MII or RMII (only the Gigabit interfaces RGMII & SGMII)
• DP83620 is a plain 10/100 PHY with RMII & fiber support
• BCM5221 (MII & RMII) & BCM5241 (MII) are plain old 10/100 PHYs but in typical broadcom fashion, they don’t even give you the datasheet to download on their website. But you can find it via Google
• BCM5248 is a 8-port PHY with fiber support
• ST802RT1 (LQFP48)
• Marvell’s 88E3015 & 88E3018 feature fiber support and have **good documentation on the fiber interface.**They are available in QFN packages but only support MII & RGMII - RMII is not supported !
• KS8721BL, KS8721SL & KSZ8721CL (LQFP/SSOP)
• KSZ8001L (LQFP/SSOP)
• KSZ8041FTL (LQFP/SSOP - you must buy the FTL variant!)
• (LQFP/SSOP)
• The VSC8211 is a Gigabit Ethernet PHY but supports 100Base-FX & RMII interface. It is available in a 117-pin BGA package and hence rather difficult to use.
• The LAN9355 3-port Ethernet switch features two 100Base-FX fiber interfaces and a RMII interface. It is more complex to use than a standalone PHY but can forward traffic without software interaction.
• The KSZ8893FQL 3-port Ethernet switch features one 100Base-FX fiber interface and a RMII interface. It is rather expensive
• The Cortina LXT971A is a simple 100Base-FX PHY from a rather unknown manufacturer. It only has MII, not RMII! Cortina appears to have been bought by Intel.
• LU3X34FTR is a 4-port 10/100 PHY with fiber support

与 DP83822 相比，在 100Base-FX 操作的背景下，无论你使用 DP83822 与否，技术差异很小。根据我的经验，Ethernet PHY 主要在电气抗扰度（ESD 等）方面有所不同，这在光纤环境中并不真正相关，除非有人直接接触 PCB，以及补偿降级 Ethernet 信号的能力（这在光纤环境中并不真正相关）。**DP83822 和许多其他部件之间唯一的真正区别是 DP83822 采用小型 VQFN 封装，而 Micrel/Microchip KSZ 设备采用更大的 SSOP 或 LQFP 封装。**我的建议是首先根据可用性选择，其次根据尺寸选择。