DS3254 데이터 시트보기 (PDF) - Maxim Integrated

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DS3254

Single/Dual/Triple/Quad DS3/E3/STS-1 LIUs

Maxim Integrated 

DS3251/DS3252/DS3253/DS3254

Table 6-B. Receiver Pin Descriptions

Note: These pins are always active.

NAME TYPE

FUNCTION

RXPn,

RXNn

RCLKn

RPOSn/

RDATn

I

Receiver Analog Inputs. These differential AMI inputs are coupled to the inbound 75Ω coaxial cable

through a 1:2 step-up transformer (Figure 2-1).

Receiver Clock. The recovered clock is output on the RCLK pin. Recovered data is output on the

O3

RPOS/RDAT and RNEG/RLCV pins on the falling edge of RCLK (RCINV = 0) or the rising edge of

RCLK (RCINV = 1). During a loss of signal (RLOS = 0), the RCLK output signal is derived from the

LIU’s master clock.

Receiver Positive AMI/Receiver Data. When the receiver is configured to have a bipolar interface

O3

(RBIN = 0), RPOS pulses high for each positive AMI pulse received. When the receiver is configured

to have a binary interface (RBIN = 1), RDAT outputs decoded binary data. RPOS/RDAT is updated

either on the falling edge of RCLK (RCINV = 0) or the rising edge of RCLK (RCINV = 1).

RNEGn/

RLCVn

Receiver Negative AMI/Line-Code Violation. When the receiver is configured to have a bipolar

interface (RBIN = 0), RNEG pulses high for each negative AMI pulse received. When the receiver is

O3 configured to have a binary interface (RBIN = 1), RLCV pulses high to flag code violations. See

Section 8.6 for further details on code violations. RNEG/RLCV is updated either on the falling edge of

RCLK (RCINV = 0) or the rising edge of RCLK (RCINV = 1).

RTSn

Receiver Tri-State Enable (Active Low). RTS tri-states the RPOS/RDAT, RNEG/RLCV, and RCLK

receiver outputs. This feature supports applications requiring LIU redundancy. Receiver outputs from

I

multiple LIUs can be wire-ORed together, eliminating the need for external switches or muxes. The

receiver continues to operate internally when RTS is low.

0 = tri-state the receiver outputs

1 = enable the receiver outputs

RLOSn

Receiver Loss of Signal (Active Low, Open Drain). RLOS is asserted upon detection of 175 ±75

consecutive zeros in the receive data stream. RLOS is deasserted when there are no excessive zero

O occurrences over a span of 175 ±75 clock periods. An excessive zero occurrence is defined as three

or more consecutive zeros in the DS3 and STS-1 modes or four or more zeros in the E3 mode. See

Section 8.5 for more information.

PRBSn

O

PRBS Detector Output. This signal reports the status of the PRBS detector. See Section 11 for

further details.

Table 6-C. Transmitter Pin Descriptions

Note: These pins are always active.

NAME TYPE

FUNCTION

TCLKn

TPOSn/

TDATn

TNEGn

TXPn,

TXNn

TDMn

TTSn

Transmitter Clock. A DS3 (44.736MHz ±20ppm), E3 (34.368MHz ±20ppm), or STS-1 (51.840MHz

I

±20ppm) clock should be applied at this signal. Data to be transmitted is clocked into the device at

TPOS/TDAT and TNEG either on the rising edge of TCLK (TCINV = 0) or the falling edge of TCLK

(TCINV = 1). See Section 9 for additional details.

Transmitter Positive AMI/Transmitter Data. When the transmitter is configured to have a bipolar

interface (TBIN = 0), a positive pulse is transmitted on the line when TPOS is high. When the

I

transmitter is configured to have a binary interface (TBIN = 1), the data on TDAT is transmitted after

B3ZS or HDB3 encoding. TPOS/TDAT is sampled either on the rising edge of TCLK (TCINV = 0) or

on the falling edge of TCLK (TCINV = 1).

Transmitter Negative AMI. When the transmitter is configured to have a bipolar interface (TBIN = 0),

I

a negative pulse is transmitted on the line when TNEG is high. When the transmitter is configured to

have a binary interface (TBIN = 1), TNEG is ignored and should be wired either high or low. TNEG is

sampled either on the rising edge of TCLK (TCINV = 0) or on the falling edge of TCLK (TCINV = 1).

Transmitter Analog Outputs. These differential AMI outputs are coupled to the outbound 75Ω

O3 coaxial cable through a 2:1 step-down transformer (Figure 2-1). These outputs can be tri-stated using

the TTS pin or the TTS or TPS configuration bits.

Transmitter Driver Monitor (Active Low, Open Drain). TDM reports the status of the transmit driver

O monitor. When the monitor detects a faulty transmitter, TDM is driven low. TDM requires an external

pullup to VDD. See Section 9.6 for more information.

Transmitter Tri-State Enable (Active Low). TTS tri-states the transmitter outputs (TXP and TXN).

This feature supports applications requiring LIU redundancy. Transmitter outputs from multiple LIUs

I

can be wire-ORed together, eliminating external switches. The transmitter continues to operate

internally when TTS is active.

0 = tri-state the transmitter output driver

1 = enable the transmitter output driver

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