Prestigio NOBILE 159W Technical & Service Manual Download

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During packet reception, the TPA and TPB transmitters of the receiving cable port are disabled,

and the receivers for that port are enabled. The encoded data information is received on the TPA
cable pair, and the encoded strobe information is received on the TPB cable pair. The received
data-strobe information is decoded to recover the receive clock signal and the serial data bits. The
serial data bits are resynchronized to the local 49.152-MHz system clock and sent to the integrated
LLC. The received data is also transmitted (repeated) on the other active (connected) cable ports.

Both the TPA and TPB cable interfaces incorporate differential comparators to monitor the line

states during initialization and arbitration. The outputs of these comparators are used by the internal
logic to determine the arbitration status. The TPA channel monitors the incoming cable
common-mode voltage. The value of this
common-mode voltage is used during arbitration to set the speed of the next packet transmission. In
addition, the TPB channel monitors the incoming cable common-mode voltage on the TPB pair for
the presence of the remotely supplied twisted-pair bias voltage.

The TSB43AB22A device provides a 1.86-V nominal bias voltage at the TPBIAS terminal for port
termination. The PHY layer contains two independent TPBIAS circuits. This bias voltage, when
seen through a cable by a remote receiver, indicates the presence of an active connection. This bias
voltage source must be stabilized by an external filter capacitor of 1.0

The line drivers in the TSB43AB22A device operate in a high-impedance current mode and are

designed to work with external 112-

Ω

line-termination resistor networks in order to match the 110-

Ω

cable impedance. One network is provided at each end of a twisted-pair cable. Each network is
composed of a pair of series-connected 56-

Ω

resistors. The midpoint of the pair of resistors that is

directly connected to the TPA terminals is connected to its corresponding TPBIAS voltage terminal.
The midpoint of the pair of resistors that is directly connected to the TPB terminals is coupled to
ground through a parallel R-C network with recommended values of 5 k

Ω

and 220 pF. The values of

the external line-termination resistors are designed to meet the standard specifications when
connected in parallel with the internal receiver circuits. An external resistor connected between the
R0 and R1 terminals sets the driver output current and other internal operating currents. This
current-setting resistor has a value of 6.34 k

Ω

1%.

When the power supply of the TSB43AB22A device is off and the twisted-pair cables are

connected, the TSB43AB22A transmitter and receiver circuitry present a high impedance to the
cable and do not load the TPBIAS voltage at the other end of the cable.

When the device is in a low-power state (for example, D2 or D3) the TSB43AB22A device
automatically enters a low-power mode if all ports are inactive (disconnected, disabled, or

TECHNICAL SERVICE MANUAL

Prestigio Nobile 159W

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