The following descriptions are mostly gathered from product briefs of the different SoCs.

Generic Layout

All SoCs have in common that they don't actually contain the DSP for the xDSL line, but are connected to a "line driver", a separate SoC providing the physical layer adaption. They contain an ADSL core and an ATM Core for offloading most DSL/ATM protocol overhead.

SoCs

First generation SoCs

BCM6335

The BCM6335 is one of the first ADSL SoCs from Broadcom and supports ADSL1.

BCM6345

The BCM6345 supports ADSL2 and has a PCMCIA interface, to be integrated in ADSL routers.

Second generation SoCs

BCM6338

An upgraded version of the BCM6335 with ADSL2+ support, USB 1.1 support as host and device.

BCM6348

An upgraded version of the BCM6345 with ADSL2+ support, support for a separate VoIP DSP. It is mostly combined with the BCM6301 line driver, but can also be combined with a BCM6505 VDSL transceiver.

BCM6358

It supports ADSL2+ through a BCM6301 line driver connected to the ADSL core and VDSL2 through a BCM6514 transceiver connected to the ATM core with a "utopia" connection. It seems to integrate an VoIP DSP.

Third generation SoCs

BCM63281/BCM63283

Low cost ADSL2+ SoC with integrated Switch.

BCM6362

ADSL2+ SoC with integrated wireless and DECT.

BCM6368

The current generation of Broadcoms ADSL SoCs, using a new architecture through a "bonding transceiver", supporting VDSL2/ADSL2+ and a second ADSL2+ connection simultaneusly.

BCM6816

Not a DSL SoC, but GPON.