Network card chip and interface circuit analysis and maintenance.

Last Update Time: 2019-07-04 17:53:41

1. Network card chip introduction.

The whole network part of motherboard is composed of network card chip, data pump and network interface. The 100MHz network card chip RTL8100C and 1000MHz card chip RTL8111E produced by Ruiyu Company are shown in figure 1. The Nic chip is mainly responsible for sending and receiving data. The data pump, as shown in figure 2, also has a network or lightning protection chip, mainly to transmit the interference in the signal isolation, its interior is composed of many coils, most of the main board in the network interface will be the data pump integrated.


(a) RTL8100C            (b) RILI1E

Figure 1. Nic chip.



Figure 2 data pump.



2. The working principle of the network card chip.

The working line of the network card chip is shown in figure 3. The network card chip connects the South Bridge chip via PCL-E bus, and connects to the network card interface through TRXP and TRXN signal lines.After the network card chip power supply, the clock signal and reset signal are normal, the South Bridge chip drinks through the PCI_E bus to identify the network card chip, and reads the information from the EEPROM chip to configure the network card chip. When the network is needed, the South Bridge chip transmits the data to the network card chip through the PCI_E bus for processing, and then exchanges the data with the network server through the network interface.


Fig. 3 the working line diagram of the Nic chip.


The application circuit of the RTL8111E Nic chip is shown in figure 4.


10MHz, 100MHz 1000MHz adaptive. Compatible with PCL-E 1.0A standard.

Support for balance testing. # supports crossover detection and auto-correction.

Supports network wake-up.

Supports full-duplex mode of operation.

Support EEE802.1QLVLAN.

Support EEPROM interface. Support low power consumption mode.

Provides 4 network status LEDs.


3. Network card chip fault maintenance method.


(1)  Can not identify the hardware maintenance method.

1) Look to see if there are any swaps around the Nic chip.


2)Measure the network card chip power supply is normal (specific feet need to check the chip data).


3)Measure whether the network card chip clock signal is normal (network card chip has two clock signals: their own 25MHz crystal oscillator and bus clock signal 33MHz/100MHz).


4) Measure if the reset signal of the Nic chip is normal (specific feet need to check the chip data).


5) Check if the network card chip bus is normal (the network card chip and the South Bridge chip connected line).


6)If the above conditions are normal, first change the Nic chip. After changing the network card chip still can not solve the fault, then change the MAC chip, and finally replace the South Bridge chip.


(2) the maintenance method of showing the unplugged wire.


1) Look for swaps.


2) Check for damage to the interface shrapnel and burn out the resistor next to the interface.


3)Replace the data pump.


4) Swap the network interface or network card chip.


(3) The maintenance method that can't get the IP address.


1) Look-and-feel for swaps around network interfaces.


2)Check that the MAC address is normal (FF-FF and 11 / 22 / 33 / 44 / 55 / 66 are invalid addresses).


3)If the above conditions are normal, first replace the MAC chip. After the replacement of the MAC chip, it is still unable to resolve the fault, finally replace the network card chip.


 This article is from Allicdata Electronics Limited which offers a varity of component made by the solid luminescent material.