KSZ9021RNI - Gigabit Ethernet PHY Transceiver, RGMII, QFN-48 | Microchip
MPN: KSZ9021RNI ✗ End of Life| Qty | Unit Price | Extended |
|---|---|---|
| 1 | $8.97 | $8.97 |
| 10 | $8.21 | $82.10 |
| 100 | $7.05 | $705.00 |
| 500 | $5.89 | $2,945.00 |
| 1,000 | $5.12 | $5,120.00 |
KSZ9021RNI Overview
A Gigabit Ethernet PHY (Physical Layer Transceiver) is a mixed-signal IC that sits between the MAC layer of an Ethernet controller and the magnetic RJ-45 interface, performing analog line encoding (PAM-5 / MLT-3 / NRZ depending on speed), echo/next-crosstalk cancellation, adaptive equalization, and clock-data recovery. The KSZ9021 belongs to the Ethernet transceiver family of physical-layer devices, within the broader power management and data communication semiconductor category, supporting 1.0 Gbps full-duplex operation per IEEE 802.3.
Key features include auto-negotiation and link detection, integrated 1.2V LDO, HP Auto-MDIX crossover support, low-power 25 MHz crystal reference, and on-chip termination resistors. The part supports Jumbo Frame sizes and Energy-Detect power-down modes. The 48-QFN exposed-pad package provides a low-thermal-resistance path suitable for industrial temperature operation from -40C to +85C.
Architecturally, the device uses a DSP-based receive path with adaptive equalization and baseline wander correction, plus a line-driving block with on-chip termination. It interfaces to the host MAC through RGMII (the default mode) at 1.8V/2.5V/3.3V tolerant I/O, simplifying SoC connection across multiple voltage rails. Per Microchip datasheet DS00003050A, the part requires a single 3.3V supply, with the internal 1.2V core regulated by an integrated LDO.
Typical applications include industrial Ethernet switches, IP cameras and surveillance equipment, network routers and gateways, broadband gateway and CPE platforms, and factory automation controllers. The wide -40C to +85C industrial temperature range makes it suitable for harsh-environment deployments where commercial-grade parts would fail.
When designing with the KSZ9021RNI, follow the reference schematic in the datasheet for the analog supply decoupling scheme (separate AVDD33/AVDD18 decoupling with ferrite beads) and route the MDI differential pairs as 100-ohm differential lines. Note: per Microchip support, the KSZ9021 family is marked "Not recommended for new designs" with the KSZ9031 family as the recommended migration path.
This page synthesizes distributor pricing, drop-in alternatives, and practical design notes that supplement the manufacturer datasheet with engineer-focused information for sourcing and design decisions.
Drop-in alternatives for KSZ9021RNI — 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 KSZ9021RNI (same form factor and footprint) — differing in Package, MAC Interface, Data Rate, Operating Temperature, Cable Diagnostics.
Quick Comparison Tool — Select alternative parts for side-by-side comparison:
KSZ9031RNXCA
✅ Drop-In📋 Reference alternative (not in catalog)
KSZ9031RNXIA
✅ Drop-In✓ In Stock
$3.27 / Unit
View Datasheet →KSZ9021RN
✅ Drop-In✓ In Stock
$6.5948 / Unit
View Datasheet →KSZ9031RNXCA-TR
✅ Drop-In📋 Reference alternative (not in catalog)
DP83867IRRGZ
✅ Drop-In✓ In Stock
$6.88 / Unit
View Datasheet →DP83869HMRGZR
✅ Drop-In✓ In Stock
$3.95 / Unit
View Datasheet →KSZ9021RNI Specifications
| Function | Ethernet Physical Layer Transceiver (PHY) |
| Data Rate | 10/100/1000 Mbps (Triple Speed) |
| Number of Drivers/Receivers | 8/8 (4 differential pairs) |
| Protocol | 10Base-T, 100Base-TX, 1000Base-T (IEEE 802.3) |
| MAC Interface | RGMII, GMII, MII |
| Supply Voltage (VDDIO) | 3.135 V to 3.465 V (3.3 V typical) |
| Core Supply (Internal LDO) | 1.14 V to 1.26 V |
| Cable Type | CAT-5 UTP, 100 m |
| Auto-MDIX | Yes (HP Auto-MDIX) |
| Auto-Negotiation | Yes, per IEEE 802.3 clause 28 |
| Jumbo Frame Support | Yes |
| Operating Temperature | -40 C to +85 C (Industrial) |
| Package | 48-QFN (7x7 mm) with Exposed Pad |
| Mounting Type | Surface Mount |
| MSL Level | 3 |
| RoHS Status | Compliant |
| Lifecycle | Not recommended for new designs (NRND) |
KSZ9021RNI Pin Configuration
| Pin 1 | TXD0 — RGMII transmit data bit 0 |
| Pin 2 | TXD1 — RGMII transmit data bit 1 |
| Pin 3 | TXD2 — RGMII transmit data bit 2 |
| Pin 4 | TXD3 — RGMII transmit data bit 3 |
| Pin 5 | TX_EN — RGMII transmit enable |
| Pin 6 | GTX_CLK — RGMII transmit clock (125 MHz) |
| Pin 7 | VDDIO — I/O supply voltage 3.3V |
| Pin 8 | RXD0 — RGMII receive data bit 0 |
| Pin 9 | RXD1 — RGMII receive data bit 1 |
| Pin 10 | RXD2 — RGMII receive data bit 2 |
| Pin 11 | RXD3 — RGMII receive data bit 3 |
| Pin 12 | RX_DV/CRS_DV — RGMII receive data valid / GMII mode |
| Pin 13 | RX_CLK — RGMII receive clock (125 MHz) |
| Pin 14 | MDIO — Management data I/O |
| Pin 15 | MDC — Management data clock |
| Pin 16 | INT_N — Interrupt output, active low |
| Pin 17 | RESET_N — Hardware reset, active low |
| Pin 18 | CLK125_EN — 125 MHz reference clock output enable |
| Pin 19 | CLK_25M — 25 MHz crystal reference or clock input |
| Pin 20 | GND — Ground |
| Pin 21 | TX_ER — Transmit error (GMII mode) |
| Pin 22 | TX_CLK — GMII transmit clock |
| Pin 23 | RX_ER — Receive error |
| Pin 24 | COL — Collision detect |
| Pin 25 | CRS — Carrier sense |
| Pin 26 | NC — Not connected |
| Pin 27 | NC — Not connected |
| Pin 28 | AVDD33 — Analog 3.3V supply |
| Pin 29 | AVDD18 — Analog 1.8V (internally regulated) |
| Pin 30 | NC — Not connected |
| Pin 31 | MDI_PLUS0 — Differential pair 0 positive |
| Pin 32 | MDI_MINUS0 — Differential pair 0 negative |
| Pin 33 | MDI_PLUS1 — Differential pair 1 positive |
| Pin 34 | MDI_MINUS1 — Differential pair 1 negative |
| Pin 35 | MDI_PLUS2 — Differential pair 2 positive |
| Pin 36 | MDI_MINUS2 — Differential pair 2 negative |
| Pin 37 | MDI_PLUS3 — Differential pair 3 positive |
| Pin 38 | MDI_MINUS3 — Differential pair 3 negative |
| Pin 39 | NC — Not connected |
| Pin 40 | NC — Not connected |
| Pin 41 | NC — Not connected |
| Pin 42 | LED0 — Link/Activity LED 0 |
| Pin 43 | LED1 — Link/Activity LED 1 |
| Pin 44 | LED2 — Speed LED 2 |
| Pin 45 | NC — Not connected |
| Pin 46 | NC — Not connected |
| Pin 47 | VDDIO — I/O supply voltage 3.3V |
| Pin 48 | NC — Not connected |
Typical Applications
KSZ9021RNI is suitable for 6 applications: Industrial Ethernet Switches, IP Cameras and Surveillance Equipment, Broadband Gateways and CPE Platforms, Factory Automation Controllers (PLC / PAC), Network Printers and Multi-Function Devices, Embedded IoT Gateways and Edge Computing.
Industrial Ethernet Switches
The KSZ9021RNI's industrial -40C to +85C temperature range and triple-speed 10/100/1000Base-T support make it a strong fit for managed and unmanaged industrial Ethernet switches deployed on the factory floor. The RGMII interface allows direct connection to common industrial SoCs (e.g., Microchip SAMA5D, NXP i.MX, TI Sitara) without external glue logic. Per the datasheet, the part's HP Auto-MDIX eliminates the need for crossed-cable manual configuration, and its integrated 1.2V LDO simplifies the switch's power tree. Compared to commercial-grade PHYs, the industrial temp grade prevents link degradation in outdoor cabinets and unheated control panels where ambient can swing 60C+ daily.
Recommended
IP Cameras and Surveillance Equipment
IP cameras require a reliable Gigabit Ethernet PHY that can stream 1080p/4K H.264/H.265 video over CAT-5 cable with low-latency and stable link-up. The KSZ9021RNI delivers 1000Base-T full-duplex with hardware-accelerated auto-negotiation and HP Auto-MDIX, allowing the camera to auto-detect cable polarity. The 48-QFN 7x7 mm footprint fits inside compact camera enclosures, and the exposed pad provides thermal dissipation for the 1W-class operating power. The industrial temp range is critical for outdoor or PoE-powered camera installations where internal enclosure temperatures can exceed 70C. The on-chip termination resistors reduce BOM cost versus discrete termination designs.
Recommended
Broadband Gateways and CPE Platforms
Broadband customer-premises equipment (CPE) such as xDSL/PON ONTs, Wi-Fi 6 gateways, and small-business routers use the KSZ9021RNI as the WAN or LAN physical-layer interface. The RGMII v1 interface (1.8V/2.5V/3.3V VDDIO) connects to gateway SoCs with flexible I/O voltage domains, and the integrated 1.2V LDO removes the need for a separate switching regulator on the PHY rail. The 25 MHz reference can use a low-cost crystal rather than a TCXO, which helps meet the sub-$10 BOM target of consumer CPE. The 1 Gbps throughput supports the latest 802.11ax Wi-Fi 6 access points and multi-gig service plans without becoming the link bottleneck.
Recommended
Factory Automation Controllers (PLC / PAC)
Programmable Logic Controllers (PLCs) and Process Automation Controllers (PACs) use the KSZ9021RNI to add deterministic Gigabit Ethernet uplink to PROFINET, EtherNet/IP, or Modbus TCP networks. The -40C to +85C operating range and the part's long-term supply guarantee (originally designed for industrial 10+ year deployments) make it suitable for control cabinets exposed to factory ambient swings. The HP Auto-MDIX simplifies wiring in industrial enclosures where crossover cable mistakes are common. The exposed-pad 48-QFN package provides robust thermal performance in DIN-rail mounted controllers where convection cooling is limited.
Recommended
Network Printers and Multi-Function Devices
Network-connected office printers, multi-function peripherals, and enterprise document scanners use the KSZ9021RNI to provide the high-bandwidth gigabit uplink needed for full-speed 1200 dpi color scanning and large-job spooling. The integrated cable diagnostics detect open and shorted pairs, enabling printer service technicians to identify cabling faults without external test equipment. The HP Auto-MDIX prevents the IT-help-desk ticket storm caused by miswired crossover cables. The 1.14V-1.26V internal LDO output and integrated termination resistors keep the BOM small enough to fit inside the printer's compact mainboard alongside the print engine controller SoC.
Recommended
Embedded IoT Gateways and Edge Computing
Edge IoT gateways aggregating sensor data over BLE, LoRa, or RS-485 need a reliable Gigabit Ethernet backhaul to push telemetry to the cloud. The KSZ9021RNI provides the wired backbone for these gateways, with the RGMII interface dropping cleanly onto industrial ARM SoCs (Microchip SAMA5D3, NXP i.MX6ULL/7D, TI Sitara AM335x). The industrial temp range supports outdoor or warehouse-edge deployments, and the part's mature driver stack in Linux, FreeRTOS+TCP, and Zephyr reduces firmware integration time. The exposed-pad package efficiently dissipates the ~1W operating power in a fanless sealed enclosure.
Recommended
Recommended Products Summary
Engineering reference data for KSZ9021RNI — comparison, design guidance, and compliance information.
Selection Guide
Comparison with Alternatives
| Parameter | This Product | KSZ9031RNXCA | KSZ9031RNXIA | KSZ9021RN | DP83867IRRGZ | DP83869HMRGZR |
|---|---|---|---|---|---|---|
| Package | 48-QFN (7x7 mm) | 48-QFN (7x7 mm) - same | 48-QFN (7x7 mm) - same | 48-QFN (7x7 mm) - same | 48-QFN (7x7 mm) - same | 48-QFN (7x7 mm) - same |
| Brand | Microchip Technology | Microchip Technology | Microchip Technology | Microchip Technology | Texas Instruments | Texas Instruments |
| Operating Temperature | -40 C to +85 C (Industrial) | 0 C to +70 C (Commercial) | -40 C to +85 C (Industrial) | 0 C to +70 C (Commercial) | -40 C to +85 C (Industrial) | -40 C to +85 C (Industrial) |
| MAC Interface | RGMII, GMII, MII | RGMII v2 (on-chip delay) | RGMII v2 (on-chip delay) | RGMII, GMII, MII | RGMII, GMII, MII | RGMII, SGMII |
| Auto-MDIX | Yes (HP Auto-MDIX) | Yes | Yes | Yes (HP Auto-MDIX) | Yes | Yes |
| Integrated 1.2V LDO | Yes | Yes | Yes | Yes | Yes | Yes |
| Jumbo Frame Support | Yes | Yes | Yes | Yes | Yes (up to 9000 bytes) | Yes |
| Lifecycle Status | NRND (Not recommended for new designs) | Active | Active | NRND | Active | Active |
Key Differentiators
- RGMII v1 + GMII + MII multi-mode interface (vs DP83869HMRGZR)
- Industrial -40C to +85C operating temperature (vs KSZ9031RNXCA)
- Mature Linux / RTOS driver ecosystem (vs KSZ9031RNXIA)
Design Notes
The KSZ9021RNI requires a single 3.3V supply on VDDIO and AVDD33, with the internal 1.2V core regulated by the integrated LDO. Per the datasheet reference schematic, place 10uF bulk + 0.1uF decoupling on each VDDIO pin and 10uF bulk + 0.1uF on AVDD33, with a ferrite bead between AVDD33 and the digital 3.3V rail to isolate analog switching noise. AVDD18 (1.8V) is generated internally - do NOT apply an external 1.8V to this pin. Total power dissipation in 1000Base-T operation is approximately 1.0W, requiring the exposed pad to be soldered to a 4-layer PCB ground plane with a minimum 4x4 via array for thermal relief.
Route the MDI differential pairs (MDI_PLUS0..3 / MDI_MINUS0..3) as 100-ohm differential lines on the top layer with continuous reference ground plane beneath, kept at least 4x the dielectric thickness away from other signals. The trace length matching target is 50 mils intra-pair and 200 mils inter-pair to preserve 1000Base-T signal integrity. Place the 25 MHz crystal within 5 mm of the CLK_25M pin with a ground guard ring. The magnetics (1:1 turns ratio, 350uH OCL typical) must be placed within 25 mm of the MDI pins. Refer to the KSZ9021RNI reference design in datasheet DS00003050A for the exact layout, including the Bob Smith termination network.
Three common design pitfalls: (1) Not soldering the exposed pad - this causes thermal runaway and erratic link behavior under load. (2) Using a 25 MHz oscillator with >50 ppm tolerance - the IEEE 802.3 spec requires the PHY reference to be within +/-50 ppm total accuracy, and many cheap crystals fail this. (3) Forgetting MDIO pull-up - the MDIO line requires a 1.5k to 10k pull-up to VDDIO; without it, register access fails. Also note: the KSZ9021RNI is in NRND status per Microchip, so new designs should consider the KSZ9031RNX family as the migration path.
Compliance Information
RoHS compliant per distributor listings on DigiKey and Octopart. REACH compliance per Microchip product page. AEC-Q100 not applicable (industrial-grade PHY, not automotive-qualified). Halogen-free status not explicitly stated in retrieved data - flagged as unknown.
