SLK2501

OC48/24/12/3 SONET/SDH MULTIRATE TRANSCEIVER

SLLS502A – OCTOBER 2001 – REVISED NOVEMBER 2001

7

POST OFFICE BOX 655303

detailed description

The SLK2501 is designed to support OC-48/24/12/3. The operating data speed can be configured through

RSEL0 and RSEL1 pins as indicated in Table 1.

Table 1. Data Rate Select

SERIAL DATA RATE

RSEL0

RSEL1

PARALLEL LVDS DATA RATE

TXCLK/RXCLK

OC-48:2.488 Gb/s

0

0

622.08 Mbps

622.08 MHz

OC-24:1.244 Gb/s

1

0

311.04 Mbps

311.04 MHz

OC-12:622 Mb/s

0

1

155.52 Mbps

155.52 MHz

OC-3:155.52 Mb/s

1

1

38.88 Mbps

38.88 MHz

The user can also enable the autorate detection circuitry through the AUTO_DETECT pin. The device

automatically detects the OC-N of the data line rate and generates two bits of output to indicate the data rate

to other devices in the system. When using AUTO_DETECT, RSEL0 and RSEL1 need to be set to 00 or be

unconnected.

Table 2. Data Rate Reporting Under Autorate Detection Mode

SERIAL DATA RATE

RATEOUT0

RATEOUT1

PARALLEL LVDS DATA RATE

TXCLK/RXCLK

OC-48:2.488 Gb/s

0

0

622.08 Mbps

622.08 MHz

OC-24:1.244 Gb/s

1

0

311.04 Mbps

311.04 MHz

OC-12:622 Mb/s

0

1

155.52 Mbps

155.52 MHz

OC-3:155.52 Mb/s

1

1

38.88 Mbps

38.88 MHz

The SLK2501 has four operational modes controlled by two configuration pins. These operational modes are

listed in Table 3. When the device is put in a certain mode, unused circuit blocks are powered down to conserve

the system power.

While the transceiver mode, transmit only mode, and receive only mode are straightforward, the repeater mode

of operation is shown in Figure 5. The receive serial data is recovered by the extracted clock, and it is then sent

back out on the transmit serial outputs. The data eye is open both vertically and horizontally in this process. In

the repeater mode, user can select to turn on the RX demux function through RX_MONITOR pin and allow the

parallel data to be presented. This feature enables the repeater device not only to repeat but also to listen in.

Table 3. Operational Modes

MODE

CONFIG0

CONFIG1

DESCRIPTION

1

0

0

Full duplex transceiver mode

2

0

1

Transmit only mode

3

1

0

Receive only mode

4

1

1

Repeater mode

high-speed electrical interface

The high-speed serial I/O uses a PECL compatible interface. The line could be directly coupled or ac-coupled.

Refer to Figures 10 and 11 for configuration details. As shown in the figures, an on-chip 100-

Ω termination

resistor is placed differentially at the receive end.

The PECL output also provide preemphasis for compensating ac loss when driving a cable or PCB backplane

over long distance. The level of the preemphasis is programmable via PRE1 and PRE2 pins. Users can use

software to control the strength of the preemphasis to optimize the device for a specific system requirement.