DS2291

022798 3/10

PIN DESCRIPTION Table 1

PIN

SYMBOL

I/O

DESCRIPTION

1,2

-

Positive Supply. 5.0 volts.

3

RCLK

O

Receive Clock. Recovered 1.544 MHz clock.

4

5

RPOS

RNEG

O

Receive Bipolar Data. Recovered bipolar data; updated on the

rising edge of RCLK. Bipolar violations are not corrected.

6

LCLK

I

Loopback Clock. Clock for loopback data. Internally pulled low

by 100K ohm.

7

8

LPOS

LNEG

I

Loopback Bipolar Data. Samples on the falling edge of LCLK

if LB is tied high. Internally pulled low by 100K ohm.

9

LB

I

Loopback Enable. Tie high to loopback data from the LPOS

and LNEG inputs to RPOS and RNEG; tie low or leave open to

obtain recovered data out of the ALBO circuitry at RPOS and

RNEG. Internally pulled low by 100K ohm.

14

RCL

O

Receive Carrier Loss. Transitions high when 192 consecutive

zeros have been received at RX+ and RX-; reset on the next

ones occurrence.

15

BPV

O

Receive Bipolar Violation. Transitions high for a full bit period

when a bipolar violation appears at RX+ and RX-. B8ZS code

words are not reported if B8ZS is tied high.

16

LOCK

O

Lock Indication. High state indicates that the recovery circuit is

phase-and frequency-locked to the signal at RX+ and RX-.

17

BL

O

Buffer Limit. Transitions high when the incoming jitter at RX+

and RX- is greater than 120Ulpp.

19

DJA

I

Disable Jitter Attenuation. Tie high to disable the jitter attenu-

ation circuitry; tie low to enable the jitter attenuation circuitry.

Internally pulled low by 100K ohm.

20

B8ZS

I

B8ZS Enable. If tied high, incoming B8ZS code words are de-

coded and replaced with eight zeros. If tied low, B8ZS code

words are not decoded. Internally pulled low by 100K ohm.

21

RST

I

Reset. Active low; a high-low-high transition will recenter the

dejitter buffer. Internally pulled high by 100K ohm.

22, 23

GND

-

Ground. 0.0 volts.

29

30

RX+

RX-

I

O

Receive Analog Input. Connects to T1 line through a 2:1 trans-

former. See Figure 4.

NOTE:

Do not connect any signal to pins 10, 11, 12, 13, 18, 24, 25, 26, 27, or 28.