VSC7177 查看數據表（PDF） - Maxim Integrated

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VSC7177

Enhanced 2:1 Port Selector for Serial ATA and Serial Attached SCSI

Maxim Integrated 

VSC7177

Data Sheet

Status Signals—Serial ATA II Protocol-based Port Selection

The P0SLTD output indicates the active host port. P0SLTD is LOW when port 1 is active and HIGH when port 0 is

active. P0SLTD is a logic HIGH when neither host port is active.

OOBPORT0 reports the state of the inactive host port’s OOB detector. OOBPORT0 reports the state of the OOB

detector from port 0’s input receiver when there is no active host.

There is no active host following a reset of the VSC7177.

Table 5 contains a summary of the protocol-based port selection operating mode.

Table 5. Operating Modes for Serial ATA II Protocol-based Port Selection

Active Host Port

Port 0

Port 1

No active host

P0OUT

P2IN

OFF(1)

P2IN

P1OUT

OFF(1)

P2IN

P2IN

Output Pins

P2OUT

P0IN

P1IN

OFF(1)

P0SLTD

1

0

1

OOBPORT0

OOBPORT1

OOBPORT0

OOBPORT0

1. OFF indicates the output driver is transmitting a common-mode state.

High-Speed Outputs

Each port has a high-speed output buffer that transmits the differential serial ATA data at rates up to 3.0 Gbps. The

output pins for the ports are P0OUTP/N, P1OUTP/N, and P2OUTP/N. Each output buffer has an input to indicate

when OOB signals are being transmitted and a single input to control the output voltage amplitude and to enable pre-

emphasis.

Data

Output

OutputN

HIV

TX Common Mode

Figure 4. High-Speed Output Buffer

Transmitting OOB Signals

Both differential output signals are at the DC-bias voltage when the output buffer is disabled. The output buffer is

disabled when OOB signals are transmitted and when an output port is turned “off” as described in “Modes of

Operation,” page 5.

Revision 4.2

July 29, 2005

10 of 24

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