Am79C874

The Am79C874 NetPHY-1LP device provides the physical (PHY) layer and transceiver functions for one 10/100 Mbps Ethernet port. It delivers the dual benefits of CMOS low power consumption and small package size. Operating at 3.3 V, it consumes only 0.3 W. Three power management modes provide options for even lower power consumption levels. The small 12x12 mm 80-pin PQL package conserves valuable board space on adapter cards, switch uplinks, and embedded Ethernet applications.

The NetPHY-1LP 10/100 Mbps Ethernet PHY Am79C874 is IEEE 802.3 compliant. It can receive and transmit data reliably at over 130 meters. It includes on-chip input filtering and output waveshaping for unshielded twisted pair operation without requiring external filters or chokes. The NetPHY-1LP Am79C874 can use 1:1 isolation transformers or 1.25:1  solation transformers. 1.25:1 isolation transformers provide 20% lower transmit power consumption. A PECL interface is available for 100BASE-FX applications.

Interface to the Media Access Controller (MAC) layer is established via the standard Media Independent Interface (MII), a 5-bit symbol interface, or a 7-wire (GPSI) interface. Auto-Negotiation determines the network speed and full or half-duplex operation. Automatic polarity correction is performed during Auto-Negotiation and during 10BASE-T signal reception.

Multiple LED pins are provided for front panel status feedback. One option is to use two bi-color LEDs to show when the device is in 100BASE-TX or 10BASE-T mode (by illuminating), Half or Full Duplex (by the color), and when data is being received (by blinking). Individual LEDs can indicate link detection, collision detection, and data being  ransmitted.

The NetPHY-1LP Am79C874 needs only one external 25- MHz oscillator or crystal because it uses a dual-speed clock  ynthesizer to generate all other required clock domains. The receiver has an adaptive equalizer/DC restoration circuit for accurate clock/data recovery from the 100BASE-TX signal.

The NetPHY-1LP Am79C874 is available in the commercial (0 to +70) or industrial (-40 to +85) temperature ranges. The industrial temperature range is well suited to environments, such as enclosures with restricted air flow or outdoor equipment.