Terminations |
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Table 5. |
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Signal |
| Comments | |
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| When the internal clock of the 31154 is used, pull |
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| high to VCC33 through an external 8.2 KΩ resistor. |
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| When an external clock source is used, tie to GND |
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| through a 330 Ω external resistor. All secondary |
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S_GCLKOEN |
| clock outputs (S_CLKO[8:0] and S_BRGCLKO) |
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| asynchronously tristate. |
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| When an external clock source is used, tie |
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| S_CLKOEN[3:0] to a stable value. Refer to |
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| S_CLKOEN[3:0], below. |
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| These are strapping pins to enable or tristate | NOTE: This strapping is meaningful only when |
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| S_CLKO[8:0] after reset. | S_GCLKOEN is pulled high. |
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| • To enable all S_CLKO[8:0], pull each | When external clocks are used, tie S_GCLKOEN |
S_CLKOEN[3:0] |
| S_CLKOEN[3:0] pin to 3.3 V through an | low and tie S_CLKOEN[3:0] to some stable value |
| external 8.2 KΩ resistor. | (0000b, for example). | |
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| • To selectively disable some of the |
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| S_CLKO[8:0], refer to 31154 Control |
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| Register 2, bits[8:0]. |
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Hot Swap |
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| For Hot Swap: |
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HS_ENUM# |
| • Connect the interrupt input pin to the host. |
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| When not using Hot Swap: |
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| • NC (there is a weak internal |
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| For Hot Swap: |
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HS_LSTAT |
| • Connect to cPCI ejector switch. |
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| When not using Hot Swap: |
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| • Tie low to GND. |
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| For Hot Swap: |
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HS_LED_OUT |
| • Connect to cPCI blue LED. |
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| When not using Hot Swap: |
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| • NC |
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| For Hot Swap: |
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| 0 = The 31154 retries any Type 0 configuration |
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| cycles addressed to it until serial ROM |
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| preload has completed (default) | 0 = Tie low to GND. |
HS_SM |
| 1 = The 31154 ignores (causes master abort) any | Ω |
| Type 0 configuration cycles addressed to it | 1 = Pull high to 3.3 V through an external 8.2 K | |
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| resistor. | |
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| until its serial ROM preload has completed. |
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| When not using Hot Swap: |
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| • Tie low to GND. |
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NOTES:
1.The recommended value for
2.The recommended value for
3.For
4.Connect PVIO and SVIO
0 Ω (3.3 V), depending on the signaling level of the primary/secondary PCI bus. Refer to the
22 | Intel® 31154 133 MHz PCI Bridge Design Guide Design Guide |