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VSC7173

Data Sheet

Revision 4.1

May 23, 2005

Confidential

Modes of Operation

Table 1 summarizes the VSC7173 operational mode choices. The mode of the VSC7173 is determined by the

following pins.

MODE1: Controls whether the selection of port 0 to port 1 is edge-sensitive or level-sensitive. When LOW, port

selection is level-sensitive (to enable level-sensitive port selection, pin PORTSEL1 must also be LOW). When HIGH,

port selection is edge-sensitive.

MODE0: Controls the function of the unselected port. When LOW, the output of this port is turned off. When HIGH,

the output of this unselected port is the same data as seen on the selected port.

PORTSEL0: In level-sensitive mode (MODE1 is LOW and PORTSEL1 is LOW), controls the selection of port 0 or

port 1. When LOW, port 0 is selected; when HIGH, port 1 is selected. In edge-sensitive mode (MODE1 is HIGH),

controls the selection of port 0; a rising edge on this pin selects port 0.

PORTSEL1: In level-sensitive mode (MODE1 is LOW), must be held LOW. In edge-sensitive mode (MODE1 is

HIGH), controls the selection of port 1; a rising edge on this pin selects port 1.

X = don’t care;

↑ = rising.

Status Pins

Two output pins, P0SLTD and OOBPORT0, are provided for status monitoring. Table 2 summarizes the functionality

of these two output pins. OOBPORT0 reports whether the signal on port 0 is above or below the threshold selected in

Table 5. P0SLTD, depending on the state of MODE1, can either report which port is selected or can report whether

the signal on port 1 is above or below the threshold selected in Table 5.

X = don’t care;

↑ = rising.

Table 1. Port Selection Operating Modes

Input Pins

High-Speed Connections

MODE1

MODE0

PORTSEL0

PORTSEL1

P0OUT

P1OUT

P2OUT

0 (level)

0

0

0

P2IN

OFF

P0IN

0 (level)

0

1

0

OFF

P2IN

P1IN

0 (level)

1

0

0

P2IN

P2IN

P0IN

0 (level)

1

1

0

P2IN

P2IN

P1IN

1 (edge)

0

X

↑

OFF

P2IN

P1IN

1 (edge)

0

↑

XP2IN

OFF

P0IN

1 (edge)

1

X

↑

P2IN

P2IN

P1IN

1 (edge)

1

↑

X

P2IN

P2IN

P0IN

Table 2. Output Status Pins

Input Pins

Output Status Pins

MODE1

PORTSEL0

PORTSEL1

P0SLTD

OOBPORT0

0 (level)

X

X

OOB status port 1—1 indicates signal is

below OOB threshold, 0 indicates signal

is above OOB threshold

OOB status port 0—1 indicates signal

is below OOB threshold, 0 indicates

signal is above OOB threshold

1 (edge)

X

↑

Indicates port selected, 0 = port 1

OOB status port 0

1 (edge)

↑

X

Indicates port selected, 1 = port 0

OOB status port 0