Part Number: KSZ8081RNBIA-TR

Manufacturer: Microchip Technology

Description: IC TRANSCEIVER FULL 1/1 32QFN

Shipped from: Shenzhen/HK Warehouse

Stock Available: Check with us

Technical Specifications of KSZ8081RNBIA-TR

Datasheet  KSZ8081RNBIA-TR datasheet
Category Integrated Circuits (ICs)
Family Interface – Drivers, Receivers, Transceivers
Manufacturer Microchip Technology
Packaging Tape & Reel (TR)
Part Status Active
Type Transceiver
Protocol RMII
Number of Drivers/Receivers 1/1
Duplex Full
Receiver Hysteresis
Data Rate
Voltage – Supply 1.8V, 2.5V, 3.3V
Operating Temperature -40°C ~ 85°C
Mounting Type Surface Mount
Package / Case 32-VFQFN Exposed Pad
Supplier Device Package 32-QFN (5×5)

KSZ8081RNBIA-TR General Description

The KSZ8081 is a single-supply 10BASE-T/100BASE-TX Ethernet physical-layer transceiver with an ordinary CAT-5 unshielded twisted pair (UTP) cable for both data transmission and reception. Regarding PHY solutions, the KSZ8081 is one of the most integrated. Using on-chip termination resistors for the differential pairs and an integrated low-noise regulator to supply the 1.2V core help keep board costs down and board layout straightforwardThe KSZ8081MNX and KSZ8081RNB have the Media Independent Interface (MII) and the Reduced Media Independent Interface (RMII), which let them connect directly to Ethernet MAC processors and switches that are MII/RMII-compliant.

The KSZ8081RNB’s clocks, including the 50 MHz RMII reference clock output, are generated from a single 25 MHz crystal. For easier system bring-up and troubleshooting during production testing and product rollout, the KSZ8081 includes diagnostic functions.

Fault detection between the KSZ8081 I/Os and the board is possible using parametric NAND tree support. Poor copper cabling can be diagnosed with the help of LinkMD® TDR-based cable diagnostics. Lead-free 32-pin QFN packages are offered for the KSZ8081MNX and KSZ8081RNB.

KSZ8081RNBIA-TR Features

  • Support for IEEE 802.3 compliant 10Base-T/100Base-TX Ethernet transceiver MII interface on a single chip (KSZ8081MNX)
  • RMII v1.2 A 50 MHz reference clock is output to the media access controller (MAC), and a 50 MHz reference clock is also an option for the interface (KSZ8081RNB)
  • Support for configuring the PHY registers of a 100 Mbps copper repeater using a back-to-back MDC/MDIO management interface is provided.
  • LED indicators for link, activity, and speed status can be set to trigger a programmable interrupt.
  • Differential pairs’ termination resistors are integrated onto the device.
  • Adjustment for drift in the baseline
  • HP You can manually adjust the auto MDI/MDI-X feature on and off to adjust for improper straight-through or crossover cable connections.
  • The fastest possible link rate (10/100 Mbps) and duplex mode (half/full) are chosen automatically through auto-negotiation.
  • Modalities for shutting down and conserving power
  • Using LinkMD’s TDR cable diagnostics, you may locate damaged copper wiring.
  • Fault detection between chip I/Os and the HBM ESD rating of the board is facilitated using a parametric NAND Tree (6 kV)
  • Diagnostic loopback modes
  • A 3.3V power supply can be used with 1.8V, 2.5V, or 3.3V VDD I/O options.
  • Core regulator voltage regulated to 1.2V built-in.
  • Packaged in a 32-pin (5 mm) QFN

Strap-in Options – KSZ8081RNB

The strap-in pins will latch when the reset is no longer asserted. In some setups, the PHY strap-in pins on the RMII signals might be locked to undesirable high/low states because the MAC RMII receive input pins are driven high/low during power-up or reset. To avoid errors in strapping in the wrong values, external pull-ups (4.7 k) or pull-downs (1.0 k) should be attached to these PHY strap-in pins.

Functional Description

BASE-T/100BASE-TX Transceiver

Fast Ethernet transceiver with a single 3.3V power supply is what the KSZ8081 is all about. It uses on-chip termination resistors for the two differential pairs. It integrates the regulator to supply the 1.2V core, making it compliant with the IEEE 802.3 Specification while reducing board cost and simplifying board architecture. The KSZ8081’s copper media compatibility includes 10BASE-T and 100BASE-TX for sending and receiving data over CAT-5 UTP cable and HP Auto MDI/MDI-X for accurate cable type recognition and correction in both straight-through and crossover configurations.

The KSZ8081MNX and the KSZ8081RNB have a Media Independent Interface (MII) enabling direct connection to other MII and RMII-compliant Ethernet MAC processors and switches. The MAC processor has full access to the KSZ8081’s control, and status registers through the MII management bus feature. The necessity for the CPU to poll for a change in PHY status is also removed, thanks to the inclusion of an interrupt pin.


The 100BASE-TX transmission function handles serialization from parallel, encoding, and transmission in 4B and 5B formats, scrambling, converting from NRZ to NRZI, and transmitting MLT3. The MII data from the MAC is first converted from parallel to serial, which results in a serial bit stream operating at 125 MHz. After the scrambler, the data and control stream is encoded in 4B/5B. To send the serialized data in MLT3 current output, it is first converted from NRZ to NRZI format. For the 1:1 transformer ratio, the output current is determined by a 6.49 k 1% resistor outside the transformer. The output signal meets the ANSI TP-PMD standard’s requirements in overshoot,  amplitude, balance, and timing jitter, with a typical rise/fall time of 4 ns. The 100BASE-TX transmitter also includes the 10BASE-waveform T’s output.


Adaptive equating, direct current (DC) restoration, data and clock recovery, NRZI-to-NRZ conversion, MLT3-to-NRZI conversion, de-scrambling, 4B/5B decoding, and serial-to-parallel conversion are all parts of the 100BASE-TX receiver function. When data arrives at the receiving end, it first passes through an equalization filter, which corrects for inter-symbol interference (ISI) caused by the twisted-pair connection. The equalizer’s properties need to be adjusted to maximize performance because amplitude loss and phase distortion are functions of cable length. The variable compensation in this setup first estimates the signal intensity based on comparisons to some known cable properties and then fine-tunes itself to achieve optimal performance.

This is a continuous process that automatically responds to new conditions, such as a shift in temperature. A DC-restoration and data-conversion block follows the equalizer in the signal chain. Baseline drift is reduced along the dynamic range thanks to the DC-restoration circuit. To get from MLT3 to NRZI, we need a differential data-conversion circuit. There is also an adaptive cutoff point. The 125 MHz clock is recovered from the NRZI signal edges by the clock-recovery circuit. After regaining the clock, the NRZI signal is transformed into NRZ. The unscrambler and 4B/5B decoder are the following devices to encounter this signal. The MAC receives its input data, initially in NRZ serial format, converted to MII format at the end of the process.

Scrambler/De-Scrambler (100BASE-TX ONLY)

The transmitted signal’s power is spread across a wider spectrum by the scrambler, which helps lower EMI and baseline drift. The scrambled signal can be retrieved with the help of a de-scrambler.


The KSZ8081MNX/RNB is compatible with the Management Data Input/Output (MDIO) management interface standard defined by IEEE 802.3. By utilizing this interface, a higher-level device, such as a MAC processor, can keep tabs on the KSZ8081MNX/RNB and adjust as needed. To check the PHY status and change the PHY settings, an external device equipped with MIIM functionality must be utilized. Clause 22.2.4 of the IEEE 802.3 Specification goes into greater depth concerning the MIIM interface.

If you require any information or would like to place an order for the KSZ8081RNBIA-TR, please contact ICRFQ, your one-stop shop for electronic sourcing components in China. We are committed to putting in the effort necessary to ensure that you are provided with the highest quality goods at the most competitive pricing.

4.8/5 - (397 votes)
Kevin Chen