VSC7938RO 查看數據表（PDF） - Vitesse Semiconductor

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VSC7938RO

SONET/SDH 3.125Gb/s Laser Diode Driver with Automatic Power Control

Vitesse Semiconductor 

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

VSC7938

SONET/SDH 3.125Gb/s

Laser Diode Driver with Automatic Power Control

Table 5: Pin Identifications

Pin Name

GND

VCC

DATA+

DATA-

CLK+

CLK-

LATCH

Pin Number

1, 2, 7, 12, 16,

20, 23, 33, 34

36, 40, 42, 45

3, 6, 8, 11, 18, 24,

27, 32, 37, 48

4

5

9

10

13

ENABLE

14

DISABLE

SLWSTRT

FAIL

NC

APCFILT

BIAS

OUT+

OUT-

MD

CAPC

RESERVED

APCSET

MODSET

BIASMAX

15

17

19

21, 26, 28, 31, 39,

41

22

25

29

30

35

38

43

44

46

47

Ground

Description

Power Supply

Positive Data Input (PECL)

Negative Data Input (PECL)

Positive Clock Input (PECL). Connect to VCC if data retiming is not used.

Negative Clock Input (PECL). Leave unconnected if data retiming is not used.

Latch Input (TTL/CMOS). Connect to VCC for data retiming and GND for direct data.

Enable Input (TTL/CMOS). If used, connect DISABLE to GND. Connect to VCC for

normal operation and GND to disable laser bias and modulation currents.

Disable Input (TTL/CMOS). If used, leave ENABLE pin floating. Connect to GND for

normal operation and VCC to disable laser bias and modulation currents.

Connect capacitor to GND to delay turn on time of bias and modulation currents.

Output (TTL/CMOS). When low, it indicates APC failure.

No Connection. Leave these pins unconnected.

No effect on device operation.

Laser Bias Current Output

Positive Modulation-Current Output. IMOD flows when input data is high.

Negative Modulation-Current Output. IMOD flows when input data is low.

Monitor Diode Input. Connect to monitor photodiode anode. Connect capacitor to

GND to filter high-speed AC monitor photocurrent.

Capacitor to GND sets dominant pole of the APC feedback loop.

Do not connect.

Resistor to GND sets desired average optical power. If APC is not used connect 100kΩ

resistor to GND.

Connect resistor to GND to set desired modulation current.

Connect resistor to GND to set maximum bias current. The APC function can subtract

from this value, but it cannot add to it.

G52349-0, Rev 3.0

01/20/01

© VITESSE SEMICONDUCTOR CORPORATION • 741 Calle Plano • Camarillo, CA 93012

Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com

Internet: www.vitesse.com

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