SMSC SMC91C100QFP

The FEAST controller implements the Ethernet MAC and a memory-management architecture intended to move frames without a host-bus bottleneck at Fast Ethernet rates. It connects to an external physical-layer interface rather than providing a complete Ethernet port by itself. The original SMC91C100 advance-information document and Microchip's LAN91C100 design note are the technical references; the later LAN91C100FD data sheet describes a related, not automatically interchangeable, variant.

• Dual-speed 10/100 Mb/s CSMA/CD MAC operation.
• MII-compatible connection to external Ethernet PHY circuitry.
• Memory-management unit with transmit and receive queues.
• 32-bit packet-buffer data path and multiple host-bus access widths.
• Legacy 208-pin QFP footprint for existing board maintenance.

The original SMSC feature list specifies 100BASE-TX, 100BASE-T4 and 10BASE-T physical interfaces, MII serial management, a seven-wire interface to a 10 Mb/s ENDEC, EEPROM-based setup, and synchronous, asynchronous or burst DMA options. It describes a 128-Kbyte external-memory arrangement and 32-, 16- and 8-bit CPU accesses. These are design capabilities, not a claim that the cataloged lot has an integrated PHY or onboard packet RAM.

The original SMC91C100 pin-configuration drawing covers 208-pin PQFP and TQFP versions. The catalog order code ends in QFP, but its stored package field is blank; this record is provisionally mapped to the existing 208-QFP register entry. Its local 208-QFP.jpg is absent, and QFP/PQFP/TQFP body dimensions must not be assumed interchangeable. Check the actual lot marking and controlled mechanical drawing.

Assembly checks

• Identify the exact 208-lead package variation.
• Confirm body size, pitch, pin-one position and lead coplanarity.
• Inspect moisture and solderability documentation for legacy stock.

The SMSC drawing groups pins for the host data/address/control bus, external packet-memory bus, MII transmit and receive signals, EEPROM, clock, power and ground. Use the exact 208-pin top-view drawing and timing tables when wiring; this summary is not a pin-by-pin netlist. The related FD device's pinout is not evidence of pin compatibility.

Verify supply, temperature, timing and absolute limits in the exact original revision before electrical design. The related LAN91C100FD data sheet cannot substitute for those checks.

LAN91C100, LAN91C100FD, SMC91C100 and LAN91C111 were checked against the internal product database and produced no exact records, so no internal substitute link is provided. The FD revision and newer Ethernet controllers require separate review of the host bus, memory interface, MAC registers, MII signaling, firmware, timing and physical footprint.

SMSC authored the original SMC91C100 FEAST advance-information document. Microchip hosts a LAN91C100/LAN91C100FD design-consideration note and a later LAN91C100FD data sheet. The latter corroborates the product family but is not used as exact-order-code proof. Obtain an archived original controlled revision and order-code/package confirmation from the supply chain before publication.

• Maintenance of legacy 10/100 Ethernet adapter boards.
• Embedded controllers with external PHY and packet memory.
• Industrial or instrumentation network interfaces that already use the FEAST host bus.
• Repair of qualified 208-pin QFP Ethernet controller assemblies.

The local catalog lists 675 units at USD 27.00 with minimum quantity 11 and no tier ladder. Distributor index views associate 675 Rochester units with an approximately USD 33.23 ten-piece DigiKey Marketplace offer and display separate Rochester tiers of USD 26.58 at 25, USD 25.25 at 100, USD 23.92 at 500, USD 22.59 at 1,000 and USD 21.26 at 10,000. These index values are not a verified dated checkout quote and do not reconcile the local MOQ or price. Leave inventory pricing unchanged pending direct distributor confirmation, lot traceability and condition review.

Keep this item in manual review and noindex. Obtain the exact SMSC controlled data sheet and package drawing, reconcile direct distributor stock and tier pricing, confirm local lot provenance and restore the 208-QFP JPG. Do not publish until all content, sourcing, pricing, package and rendering checks pass.