DS2155 datasheet(31/262 Pages) DALLAS

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DS2156

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3.7

Line Interface Pins

Signal Name:

MCLK

Signal Description:

Master Clock Input

Signal Type:

Input

A (50ppm) clock source is applied at this pin. This clock is used internally for both clock/data recovery and for the

jitter attenuator for T1 and E1 modes. A quartz crystal of 2.048MHz can be applied across MCLK and XTALD

instead of the clock source. The clock rate can be 16.384MHz, 8.192MHz, 4.096MHz, or 2.048MHz. When using

the DS2156 in T1-only operation, a 1.544MHz (50ppm) clock source can be used.

Signal Name:

XTALD

Signal Description:

Quartz Crystal Driver

Signal Type:

Output

A quartz crystal of 2.048MHz (optional 1.544MHz in T1-only operation) can be applied across MCLK and

XTALD instead of a clock source at MCLK. Leave open circuited if a clock source is applied at MCLK.

Signal Name:

8XCLK

Signal Description:

Eight Times Clock (8x)

Signal Type:

Output

An 8x clock that is locked to the recovered network clock provided from the clock/data recovery block (if

the jitter attenuator is enabled on the receive side) or from the TCLKI pin (if the jitter attenuator is

enabled on the transmit side).

Signal Name:

LIUC

Signal Description:

Line Interface Connect

Signal Type:

Input

Connect low to separate the line interface circuitry from the framer/formatter circuitry and activate the

TPOSI/TNEGI/TCLKI/RPOSI/RNEGI/RCLKI pins. Connect high to connect the line interface circuitry to the

framer/formatter circuitry and deactivate the TPOSI/TNEGI/TCLKI/RPOSI/RNEGI/RCLKI pins. When LIUC is

connected high, the TPOSI/TNEGI/TCLKI/RPOSI/RNEGI/RCLKI pins should be connected low.

Signal Name:

RTIP and RRING

Signal Description:

Receive Tip and Ring

Signal Type:

Input

Analog inputs for clock recovery circuitry. These pins connect through a 1:1 transformer to the network. See

Section 23 for details.

Signal Name:

TTIP and TRING

Signal Description:

Transmit Tip and Ring

Signal Type:

Output

Analog line driver outputs. These pins connect through a 1:2 step-up transformer to the network. See Section 23 for

details.

DS2155 Datasheet(PDF) 31 Page - Dallas Semiconductor

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