Intel 31154 manual Power Sequencing, Intel 133 MHz PCI Bridge, Power Considerations

Models: 31154

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8.2Power Sequencing
PVIO Voltage Protection Diode

Power Considerations

8.2Power Sequencing

When either P_VIO or S_VIO is connected to a power supply other than VCCP, you must perform one of the following steps (listed in order from most favorably recommended to least favorably recommended):

1.Ensure that the P_VIO or S_VIO power comes up before or simultaneously with VCCP, and ensure that the P_VIO or S_VIO power goes down after or simultaneously with VCCP.

2.Alternatively, when the recommendation in item 1 is not followed, install a Schottky diode, as

shown in Figure 20, between VCCP and the VIO pin(s) (as appropriate). The diode must be sized appropriately for the power environment of the system.

3.Alternatively, when the recommendations in item 1 and item 2 are not followed, connect a

25 current-limiting resistor in series with the P_VIO and S_VIO supply. P_VIO and S_VIO

must never be at a voltage lower than￿￿￿￿￿￿￿V￿￿￿￿CCP ￿except in the case of a 25 current-limiting resistor in series with the P_VIO and S_VIO supply.

Figure 20.

VCP

VIO

Intel® 31154

133 MHz PCI Bridge

￿￿￿￿￿￿￿￿

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Intel® 31154 133 MHz PCI Bridge Design Guide Design Guide

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Intel 31154 manual Power Sequencing, Intel 133 MHz PCI Bridge, Power Considerations