EQCO875SC.3

Specialized Overview

The EQCO875SC.3 is a single-coax transceiver designed for Fast Ethernet connections over a single 75Ω coax cable. It integrates transmitter, receiver, and equalizer functions to support full-duplex bidirectional communication at a 125 Mbps data rate. The device operates from a single 3.3V supply with a typical power consumption of 205 mW. It connects seamlessly to any FX-compliant physical layer controller (PHY) using 4B/5B encoded signals. Key electrical parameters include a supply voltage of 3.3V, a differential input termination of 110Ω, and an output impedance of 75Ω. The component is housed in a 16-pin, 0.65 mm pitch, 4x4 mm QFN package.

Specialized Feature Summary

• Integrated equalizer compensates for cable attenuation through auto-adaptive control loops.
• Supports Power over Ethernet (PoE) distribution over the coaxial medium.
• Includes on-chip termination resistors to minimize external discrete components.
• Features transmit wake-up detection to enter low-power mode when no signal is present.

Specialized Applications

• Camera networks including home security, surveillance, industrial inspection, and medical cameras
• Home networking utilizing existing 75Ω coax infrastructure where Cat5 or Cat6 cabling is unavailable
• TV, set-top box, and PVR inter-room connections

Specialized Procurement Notes

Verify the specific ordering suffix against the manufacturer's product identification system to confirm packaging type. Suffixes such as -TRAY indicate tray packaging, while blank suffixes denote tube packaging. Confirm that the procurement channel provides genuine Microchip Technology products to ensure compliance with RoHS standards and Pb-free specifications.

Specialized Selection Notes

Select the EQCO875SC.3 specifically for applications requiring transmission over 75Ω coaxial cables. For systems utilizing 50Ω coaxial infrastructure, the EQCO850SC.3 variant should be selected instead. Ensure the connected PHY controller supports the required 125 Mbps data rate and 4B/5B encoding format for proper protocol compatibility.

Specialized Part Context

This component belongs to the EQCO family of single-coax transceivers developed by Microchip Technology. It serves as a specialized interface solution for extending Fast Ethernet connectivity over legacy coaxial wiring. The device complements standard PHY controllers by handling the physical media dependent (PMD) layer requirements for coaxial transmission.

Specialized Replacement Considerations

The EQCO850SC.3 is the sister product designed for 50Ω coaxial systems. While functionally similar, it is not electrically compatible with 75Ω cables without modification. No other direct substitutes are documented in the official datasheet.

Specialized FAQ

How does the device handle signal attenuation over long distances?

The EQCO875SC.3 utilizes an embedded high-speed equalizer with variable gain. This equalizer automatically determines the necessary frequency response to compensate for cable attenuation using a time-continuous feedback loop.

What is the purpose of the REF pin connection?

The REF pin carries a precise anti-phase current to the transmit current on the SDIO pin. It must be connected directly to AGND via a resistor precisely matched to the characteristic impedance of the coaxial cable used.

Can this device operate without Power over Ethernet?

Yes. While the device fully supports PoE-based power and data distribution, the inductor L1 and capacitor C10 in the application circuit can be removed if PoE functionality is not required.