DS2187

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0 CODE SUPPRESSION

The device will decode incoming B8ZS (RCLKSEL=0) or HDB3 (RCLKSEL=1) code words and replace

them with an all-0 code when ZCSEN=1. When ZCSEN=0, code words will pass through the device

without being altered. This feature can be disabled when the DS2187 is used with transceiver devices

such as the DS2180A DS2181A, DS2141A, or DS2143.

ALARM DETECTION

The extracted data is monitored for network alarm and error conditions. RCL is set when 192 consecutive

0s occur; it is cleared on the next one occurrence. AIS is set when less than three 0s have appeared at

violations as they occur at RPOS and RNEG; B8ZS code words will not be flagged by BPV when

ZCSEN=1.

BYPASSING AND

LAYOUT CONSIDERATIONS

The DS2187 contains both precision analog and high-speed digital circuitry on the same chip. The power

supplies of these circuits (AVDD, AVSS, DVDD and DVSS) should be connected to system analog and

digital supplies. If separate system supplies do not exist, the appropriate supply pins can be tied together.

Tying the analog and digital supplies together on the DS2187 will not degrade its performance, provided

the power supply is sufficiently decoupled.

To assure optimum performance, the length of LCAP, RTIP and RRING printed circuit board traces

should be minimized and isolated from neighboring interconnect.