STE10/100A - Reference Design NIC card/Board |
| 1 |
The STE10/100 PCI card does not completely power up and refuses to boot up. Why?
The STE10/100A PCI Card uses 3.3V, 5V and 12V supplies from the PCI bus (please see schematic in the STE10/100A app note due to the implementation for ACPI and Wake on LAN used. If all these supplies are not available, then it is possible that the board will not completely power-up and thereby also prevent the PC from booting. However, the board can be modified to use only 5V and 3.3V by adding a wire to connect the positive side of polarized capacitor C5 to the positive side of polarized capacitor C29 and removing either regulator U9 or transistor Q2.
Also, if the crystal does not oscillate, then the chip will not come out of reset and it can cause the same problem described. |
| 2 |
What is the list of vendors for the transformers that are tested by ST while using the STE10/100A?
ST has tested the following list of transformers with the STE10/100A:
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Transpower Technologies: Part # HB626-1 |
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Pulse Engineering: Part # H1102 |
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| 3 |
Could you explain in more detail about the ferrite beads used on the board design?
The ferrite beads should have 90 ohms impedance at 100MHz and be able to handle about 200-300mA each. |
| 4 |
PCI tests run successfully, but the transmitter lines coming directly from the chip are both always at low level. Why?
The most probable causes are:
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Bad connection from center-tap of transformer (pin 2 of HB626) to AVddT (0 ohms resistor R22 in ST demo board schematic) |
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NOTE: You cannot make a correct test of the voltage on the Tx+ and TX- pins without this connection. If this connection is not present, there will not be the correct voltage on the TX pins, and the signal will not be properly driven on the twisted pair.
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Bad connections for pull-up resistors on TX+ and TX- pins (R20 and R21 in ST demo board schematic). These are necessary for impedance matching. |
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Bad connection from Iref (pin 101) to 4.99K resistor to ground (R1 in ST demo board schematic) |
Please note that without the transformer and the pull-up resistors, you will not see the voltage on TX+ and TX- that you expect. These outputs do not source current or voltage, and so it is necessary to connect the center-tap of the transformer to AVddT (5Volts). |
| 5 |
Is there a formula in programming EEPROM of the STE10/100A? Where can this info be found?
Yes, the details on how to program the EEPROM along with the EEPROM CRC Calculation Algorithm can be found in the STE10/100A EEPROM Access and Programming application note is available. |
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