Datasheet

DS21352/DS21552
24 of 137
4.1.6 LINE INTERFACE PINS
Signal Name:
MCLK
Signal Description:
Master Clock Input
Signal Type:
Input
A 1.544 MHz (50 ppm) clock source with TTL levels is applied at this pin. This clock is used internally for both clock/data
recovery and for jitter attenuation. A quartz crystal of 1.544 MHz may be applied across MCLK and XTALD instead of the
TTL level clock source.
Signal Name:
XTALD
Signal Description:
Quartz Crystal Driver
Signal Type:
Output
A quartz crystal of 1.544 MHz may be applied across MCLK and XTALD instead of a TTL level clock source at MCLK.
Leave open circuited if a TTL clock source is applied at MCLK.
Signal Name:
8XCLK
Signal Description:
Eight Times Clock
Signal Type:
Output
A 12.352 MHz clock that is locked to the 1.544 MHz 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). Can be internally
disabled by writing a 08h to TEST2.3 if not needed.
Signal Name:
LIUC
Signal Description:
Line Interface Connect
Signal Type:
Input
Tie low to separate the line interface circuitry from the framer/formatter circuitry and activate the
TPOSI/TNEGI/TCLKI/RPOSI/RNEGI/ RCLKI pins. Tie 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 tied high, the
TPOSI/TNEGI/TCLKI/ RPOSI/RNEGI/RCLKI pins should be tied low.
Signal Name:
RTIP & RRING
Signal Description:
Receive Tip and Ring
Signal Type:
Input
Analog inputs for clock recovery circuitry. These pins connect via a 1:1 transformer to the T1 line. See Section 16 for details.
Signal Name:
TTIP & TRING
Signal Description:
Transmit Tip and Ring
Signal Type:
Output
Analog line driver outputs. These pins connect via a transformer to the T1 line. See Section 16 for details.