2.1 Detailed Terminal Descriptions

Please see Table 2−4 through Table 2−19 for more detailed terminal descriptions. The following list defines the column headings and the abbreviations used in the detailed terminal description tables.

I/O Type:

I = Digital input

O = Digital output

I/O = Digital input/output

AI = Analog input

PWR = Power

GND = Ground

Input/Output Description:

AF = Analog feedthrough

TTLI1 = 5-V tolerant TTL input buffer

TTLI2 = 5-V tolerant TTL input buffer with hysteresis

TTLO1 = 5-V tolerant low-noise 4-mA TTL output buffer

PCII1 = 5-V tolerant PCI input buffer

PCII2 = 5-V tolerant PCI input buffer

PCII3 = 5-V tolerant PCI input buffer

PCII4 = 5-V tolerant PCI input buffer

PCII5 = 5-V tolerant PCI input buffer

PCIO2 = 5-V tolerant PCI output buffer

PCIO4 = 5-V tolerant PCI output buffer

PCIO5 = 5-V tolerant PCI output buffer

LVCI1 = LVCMOS input buffer

LVCO1 = Low-noise 4-mA LVCMOS open drain output buffer

LVCO2 = Low-noise 4-mA LVCMOS open drain output buffer

LVCO3 = Low-noise 8-mA LVCMOS open drain output buffer

PU/PD signifies whether the terminal has an internal pullup or pulldown resistor. These pullups are disabled and enabled by design when appropriate to preserve power.

PD1 = 20- A failsafe pulldown

PD2 = 100- A failsafe pulldown

PU1 = 200- A pullup

PU2 = 100- A pullup

PU3 = 100- A pullup

PU4 = 100- A pullup

SW = Switchable 50- A pullup/200-A pulldown implemented depending on situation

Power Rail signifies which rail the terminal is clamped to for protection.

External Components signifies any external components needed for normal operation.

Pin Strapping (If Unused) signifies how the terminal must be implemented if its function is not needed.

The terminals are grouped in tables by functionality, such as PCI system function, power-supply function, etc. The terminal numbers are also listed for convenient reference.

2−13

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Texas Instruments PCI7421, PCI7411, PCI7611, PCI7621 manual Detailed Terminal Descriptions, 13