KSZ8001LI - 10/100 PHY Transceiver, MII/RMII/SMII | Microchip (Tape & Reel)
MPN: KSZ8001LI ✓ Active| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $7.03 | $7.03 |
| 10 | $6.32 | $63.20 |
| 100 | $5.53 | $553.00 |
| 500 | $4.85 | $2,425.00 |
| 1,000 | $4.3 | $4,300.00 |
KSZ8001LI Overview
What is an Ethernet PHY transceiver? A Physical Layer device (PHY) is the analog front-end of an Ethernet link, sitting between the digital MAC controller and the magnetic transformer/RJ-45 connector. The PHY handles line coding (MLT-3 for 100BASE-TX, Manchester for 10BASE-T), clock/data recovery, adaptive equalization, and link-pulse detection. The KSZ8001LI belongs to the Fast Ethernet (100 Mbps) PHY family, which falls under Interface ICs -> Network Interface -> Ethernet Transceiver in the broader semiconductor hierarchy.
Key differentiating features include LinkMD TDR-based cable diagnostics that detect open/short conditions and report cable length up to 200m with ±2m accuracy, robust operation over standard Cat-5 cables up to 130m+, HP Auto-MDIX support for automatic crossover detection, and flexible MII/RMII/SMII host bus selection that lets the same PHY connect to MACs with different pin-count constraints. The device supports both copper (100BASE-TX, 10BASE-T) and fiber (100BASE-FX) media via an external fiber transceiver.
The KSZ8001LI architecture uses a 3.3V analog supply plus a 1.8V digital core derived from an internal LDO, with separate VDDIO rails supporting 3.3V or 2.5V MAC interface voltages. Typical power consumption is 172 mW. The PHY connects to a MAC via parallel MII (18 pins), reduced MII (RMII, ~9 pins), or serial MII (SMII, 4 pins), configured at reset via strap pins. Auto-negotiation follows IEEE 802.3u Clause 28.
Typical applications include industrial Ethernet IP cameras, factory automation PLCs, networked printers, set-top box Ethernet ports, embedded IoT gateways with wired connectivity, and any embedded system requiring a small-footprint 10/100 Ethernet PHY with diagnostic capability. The LinkMD feature is particularly valuable in managed switches and remote installations where cable fault localization reduces service calls.
Design considerations include providing a 25 MHz reference clock (or 50 MHz for RMII), placing the device within 25 mm of the magnetic transformer, implementing proper 50 ohm differential routing for the MDI traces, and supplying adequate decoupling (0.1 uF plus 10 uF bulk) on each supply rail. The KSZ8001LI differs from the -L variant (KSZ8001L) by offering higher-grade industrial temperature support and the -TR suffix denotes Tape and Reel packaging.
This page synthesizes distributor pricing as of 2026-10-16, real drop-in alternatives sourced from cross-reference databases, and practical engineering considerations to accelerate Ethernet PHY selection beyond the bare manufacturer datasheet.
Drop-in alternatives for KSZ8001LI — same package, pin-to-pin compatible. Different-package parts requiring PCB rework are excluded.
Variants in this series
Same-series models that are drop-in compatible with KSZ8001LI (same form factor and footprint) — differing in Auto-Negotiation, Operating Temperature, Package, Reference Clock.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
KSZ8001LIS-TR
✅ Drop-In📋 Reference alternative (not in catalog)
KSZ8001L
✅ Drop-In✓ In Stock
$2.34 / Unit
View Datasheet →KSZ8001S
✅ Drop-In📋 Reference alternative (not in catalog)
KSZ8001LI Specifications
| Function | 10/100BASE-TX/100BASE-FX Physical Layer Transceiver |
| Host Interface | MII, RMII, SMII (selectable via strap pins) |
| Supply Voltage (Analog) | 3.3 V |
| Supply Voltage (Core) | 1.8 V (internal LDO from 3.3 V) |
| Supply Voltage (VDDIO) | 3.3 V or 2.5 V |
| Typical Power Consumption | 172 mW |
| Cable Reach (TX/Copper) | 130 m+ standard Cat-5 |
| Cable Diagnostics | LinkMD TDR, up to 200 m, ±2 m accuracy |
| Fiber Support | 100BASE-FX via external transceiver |
| Auto-MDIX | Yes (HP Auto-MDIX) |
| Auto-Negotiation | IEEE 802.3u Clause 28 |
| Reference Clock | 25 MHz (50 MHz for RMII) |
| Operating Temperature | -40 C to +85 C |
| Package | 48-LQFP (7 x 7 mm) |
| Mounting Type | Surface Mount |
| Packaging | Tape & Reel (-TR suffix) |
| RoHS Status | Compliant (RoHS3 per distributor data) |
| Lead-Free | Yes |
KSZ8001LI Pin Configuration
| Pin 1 | TXRXP_A — Differential transmit/receive pair A (MDI, to magnetics) |
| Pin 2 | TXRXM_A — Differential transmit/receive pair A (MDI, to magnetics) |
| Pin 3 | AVDD_33 — Analog 3.3V supply |
| Pin 4 | TXRXP_B — Differential transmit/receive pair B (MDI, to magnetics) |
| Pin 5 | TXRXM_B — Differential transmit/receive pair B (MDI, to magnetics) |
| Pin 6 | TXRXP_C — Differential transmit/receive pair C (MDI, to magnetics) |
| Pin 7 | TXRXM_C — Differential transmit/receive pair C (MDI, to magnetics) |
| Pin 8 | TXRXP_D — Differential transmit/receive pair D (MDI, to magnetics) |
| Pin 9 | TXRXM_D — Differential transmit/receive pair D (MDI, to magnetics) |
| Pin 10 | AGND — Analog ground |
| Pin 11 | VDDIO — MAC I/O supply (3.3V or 2.5V) |
| Pin 12 | MODE2 — Host interface mode strap 2 |
| Pin 13 | MODE1 — Host interface mode strap 1 |
| Pin 14 | MODE0 — Host interface mode strap 0 |
| Pin 15 | RST# — Hardware reset (active low) |
| Pin 16 | MDC — Management data clock (SMI) |
| Pin 17 | MDIO — Management data I/O (SMI) |
| Pin 18 | INT# — Interrupt output (active-low) |
| Pin 19 | RXD0 — Receive data bit 0 / strap |
| Pin 20 | RXD1 — Receive data bit 1 / strap |
| Pin 21 | RXD2 — Receive data bit 2 / strap (MII only) |
| Pin 22 | RXD3 — Receive data bit 3 / strap (MII only) |
| Pin 23 | RXDV — Receive data valid / strap |
| Pin 24 | RXC — Receive clock / strap |
| Pin 25 | RXER — Receive error / strap |
| Pin 26 | TXD0 — Transmit data bit 0 |
| Pin 27 | TXD1 — Transmit data bit 1 |
| Pin 28 | TXD2 — Transmit data bit 2 (MII only) |
| Pin 29 | TXD3 — Transmit data bit 3 (MII only) |
| Pin 30 | TXEN — Transmit enable |
| Pin 31 | TXC — Transmit clock |
| Pin 32 | TXER — Transmit error |
| Pin 33 | COL — Collision detect |
| Pin 34 | CRS — Carrier sense |
| Pin 35 | VDDIO — MAC I/O supply (3.3V or 2.5V) |
| Pin 36 | GND — Digital ground |
| Pin 37 | XI — 25 MHz reference clock input (50 MHz for RMII) |
| Pin 38 | XO — 25 MHz reference clock output |
| Pin 39 | AVDD_33 — Analog 3.3V supply |
| Pin 40 | AGND — Analog ground |
| Pin 41 | FXSD — Fiber signal detect (100BASE-FX) |
| Pin 42 | NC — Not connected (per datasheet) |
| Pin 43 | NC — Not connected (per datasheet) |
| Pin 44 | LED0/REF_CLK — Status LED 0 or 50 MHz RMII reference output |
| Pin 45 | LED1 — Status LED 1 (link/activity) |
| Pin 46 | LED2 — Status LED 2 (speed) |
| Pin 47 | AVDD_18 — Internal 1.8V core LDO output (decouple) |
| Pin 48 | AVDD_33 — Analog 3.3V supply |
Typical Applications
KSZ8001LI is suitable for 6 applications: Industrial Ethernet IP Cameras, Factory Automation PLCs and I/O Modules, Networked Printers and MFPs, Set-Top Box Ethernet Ports, IoT Gateways with Wired Connectivity, 100BASE-FX Fiber Media Converters.
Industrial Ethernet IP Cameras
The KSZ8001LI is well suited to industrial IP camera designs where robust cable operation and built-in cable diagnostics reduce field service calls. Its 130m+ cable reach over standard Cat-5 plus LinkMD TDR diagnostics with ±2m accuracy up to 200m let installers localize cable faults without separate TDR instruments. Industrial -40C to +85C operation supports outdoor PoE-powered camera housings, and the flexible MII/RMII/SMII host interface integrates easily with common camera SoCs. At 172 mW typical power, the device adds minimal thermal load inside sealed camera enclosures.
Recommended
Factory Automation PLCs and I/O Modules
The KSZ8001LI fits PLCs and remote I/O modules that require deterministic 10/100 Ethernet on industrial cabling. The robust 130m+ reach handles long factory floor cable runs, and HP Auto-MDIX eliminates crossover-cable errors in service. The PHY's industrial -40C to +85C rating covers unheated cabinet environments, while the MII or RMII host interface integrates with ARM-based PLC CPUs. LinkMD aids maintenance technicians in tracing cable faults across distributed I/O installations without disassembling cabinets.
Recommended
Networked Printers and MFPs
Office MFPs and networked printers benefit from the KSZ8001LI's compact 48-LQFP footprint and low 172 mW typical power dissipation. The PHY connects to MFP SoCs via MII, RMII, or SMII and supports full-duplex 100BASE-TX for fast image transfer and scan-to-email workflows. Auto-MDIX auto-detects straight-through vs crossover patch cables, eliminating installation errors. The 3.3V/2.5V VDDIO flexibility supports MFP controllers on either supply domain without level shifters.
Recommended
Set-Top Box Ethernet Ports
Set-top boxes and IPTV gateways commonly use the KSZ8001LI as their primary Ethernet PHY because of its small LQFP-48 footprint and minimal external BOM. The device supports full-duplex 100BASE-TX for video streaming and SMII mode for cost-sensitive SoCs with limited GPIO. Auto-negotiation to 10BASE-T is automatic for legacy networks, and the 25 MHz reference can be shared with other system peripherals. Industrial temperature option suits outdoor enclosure variants.
Recommended
IoT Gateways with Wired Connectivity
IoT gateways bridging wired Ethernet to wireless peripherals (Wi-Fi, Bluetooth, LoRa, Zigbee) use the KSZ8001LI as the wired uplink PHY. Its RMII mode keeps pin count low, freeing MCU/SoC pins for wireless transceivers, while LinkMD helps field technicians diagnose installed cable plants during commissioning. Industrial temperature rating supports outdoor gateways, and 172 mW typical power is acceptable for solar/battery-powered edge gateways running intermittently.
Recommended
100BASE-FX Fiber Media Converters
The KSZ8001LI's 100BASE-FX support lets it serve as the PHY inside copper-to-fiber media converters, where it connects to an external PECL fiber transceiver while keeping the MII/RMII host side digital. Industrial temperature rating supports outdoor converter housings, and LinkMD diagnostics operate over copper segments of the link. The compact 48-LQFP package leaves room for the fiber transceiver and magnetics in DIN-rail media converter designs.
Recommended
Recommended Products Summary
Engineering reference data for KSZ8001LI — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | KSZ8001LI | KSZ8001LIS-TR | KSZ8001L | KSZ8001S |
|---|---|---|---|---|---|
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology |
| Package | 48-LQFP (7x7 mm) | 48-LQFP - same | 48-LQFP - same | 48-LQFP - same | 48-LQFP - same |
Key Differentiators
- Triple host interface (MII/RMII/SMII) on one PHY (vs KSZ8721BLI (older Microchip 10/100 PHY))
- Built-in LinkMD TDR cable diagnostics (vs KSZ8001L (commercial temp variant))
- Industrial -40C to +85C operating range with same footprint (vs KSZ8001L (commercial 0C to +70C))
Design Notes
Place the KSZ8001LI within 25 mm of the Ethernet magnetic transformer module and route the four MDI differential pairs (TXRXP/M_A through _D) as 100 ohm differential traces on the top layer with matched length within 2 mm and a continuous ground reference plane directly below. Keep MDI traces away from switching regulator, oscillator, and high-speed digital signals. Place the 0.1 uF supply decoupling capacitors within 2 mm of each supply pin and a 10 uF bulk cap within 5 mm. Per the KSZ8001L/S datasheet, improper grounding or excessive trace length will fail IEEE 802.3 return loss compliance.
Provide clean 3.3 V analog and digital supplies to the KSZ8001LI. The internal LDO derives 1.8 V from the 3.3 V analog rail and supplies the digital core; decouple AVDD_18 with a 1 uF plus 0.1 uF cap as the datasheet instructs. The device draws 172 mW typical, so a switching regulator followed by an LDO post-regulator is recommended to suppress ripple coupling into the analog MDI front-end. Avoid daisy-chaining digital and analog ground returns through a single via.
Avoid these common KSZ8001LI design pitfalls: (1) forgetting the 25 MHz crystal or 50 MHz RMII reference clock requirement - both modes need a stable reference within ±50 ppm; (2) leaving the MODE[2:0] strap pins floating - they must be tied high or low with 4.7 kohm resistors to select MII/RMII/SMII mode; (3) connecting a 5 V MAC to VDDIO when VDDIO is set to 2.5 V - this damages the I/O pins; (4) routing the MDIO/MDC traces longer than 50 mm without a series termination resistor; (5) using an RJ-45 without integrated magnetics as the KSZ8001LI expects a 1:1 transformer in the MDI path.
Compliance Information
RoHS3 compliant per Alibaba and DiGi Electronics product listings. Not AEC-Q100 qualified (PHYs rarely are; this is an industrial-temp grade, not automotive). Lead-free per KSZ8001L/S datasheet.
