SY87701L

2

Micrel

PIN DESCRIPTIONS

INPUTS

RDINP, RDINN [Serial Data Input] Differential PECL.

These built-in line receiver inputs are connected to the

differential receive serial data stream. An internal receive

PLL recovers the embedded clock (RCLK) and data

(RDOUT) information. The incoming data rate can be within

one of eight frequency ranges depending on the state of

the FREQSEL pins. See “Frequency Selection” Table.

REFCLK [Reference Clock] TTL input.

This input is used as the reference for the internal

frequency synthesizer and the “training” frequency for the

receiver PLL to keep it centered in the absence of data

coming in on the RDIN inputs.

CD [Carrier Detect] PECL Input.

This input controls the recovery function of the Receive

PLL and can be driven by the carrier detect output of optical

modules or from external transition detection circuitry. When

this input is HIGH the input data stream (RDIN) is recovered

normally by the Receive PLL. When this input is LOW the

data on the inputs RDIN will be internally forced to a constant

LOW, the data outputs RDOUT will remain LOW, the Link

Fault Indicator output LFIN forced LOW and the clock

recovery PLL forced to lock onto the clock frequency

generated from REFCLK.

PLLSP

TCLKN

18

11

PLLSN

CLKSEL

17

12

GND

PLLRP

16

13

GND

PLLRN

15

14

1

VCCA

LFIN

DIVSEL1

RDINP

RDINN

FREQSEL1

REFCLK

FREQSEL2

FREQSEL3

N/C

28 VCC

CD

DIVSEL2

RDOUTP

RDOUTN

VCCO

RCLKP

RCLKN

VCCO

TCLKP

27

26

25

24

23

22

21

20

19

2

3

4

5

6

7

8

9

10

Top View

SOIC

Z28-1

PIN CONFIGURATION

1

2

3

4

5

6

7

8

24

23

22

21

20

19

18

17

NC

RDINP

RDINN

FREQSEL1

REFCLK

FREQSEL2

FREQSEL3

NC

RDOUTP

RDOUTN

VCCO

RCLKP

RCLKN

VCCO

TCLKP

TCLKN

9

10

11

12

13

14

15

16

32

31

30

29

28

27

26

25

Top View

EP-TQFP

H32-1

FREQSEL1, ..., FREQSEL3 [Frequency Select] TTL

Inputs.

These inputs select the output clock frequency range as

shown in the “Frequency Selection” Table.

DIVSEL1, DIVSEL2 [Divider Select] TTL Inputs.

These inputs select the ratio between the output clock

frequency (RCLK/TCLK) and the REFCLK input frequency

as shown in the “Reference Frequency Selection” Table.

CLKSEL [Clock Select] TTL Input.

This input is used to select either the recovered clock of

the receiver PLL (CLKSEL = HIGH) or the clock of the

frequency synthesizer (CLKSEL = LOW) to the TCLK

outputs.

OUTPUTS

LFIN [Link Fault Indicator] TTL Output.

This output indicates the status of the input data stream

RDIN. Active HIGH signal is indicating when the internal

clock recovery PLL has locked onto the incoming data

stream. LFIN will go HIGH if CD is HIGH and RDIN is within

the frequency range of the Receive PLL (1000ppm). LFIN

is an asynchronous output.