VITESSE VSC7938RO, VSC7938W Datasheet

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

VSC7938

SONET/SDH 3.125Gb/s

Laser Diode Driver with Automatic Power Control

G52349-0, Rev 3.0 Page 1 01/20/01

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

Internet: www.vitesse.com

Features Applications

General Description

The VSC7938 is a single 3.3V or 5V supply l aser diode driv er special ly desig ned for S DH/SONET appli cations up to 3.125Gb/s. External resistors set a wide range of bias and modulation currents for driving the laser. Data and clock inputs accept differential PECL signals. The autom atic power control (APC) loop maintains a constant average optical power over temperature and lifetime. The dominant pole of the APC loop can be controlled with an external capacitor. Other features include enable/disable control, short-circuit protection for the modulation and bias inputs, short rise and fall times, programmable slow-start circuit to set laser turn-on delay, and failure-monitor output to indicate when the APC loop is unable to maintain the average optical power. The VSC7938 is available in die form or in a 48-pin TQFP package.

Block Diagram

• Power Supply: 3.3V or 5V ±5%

• AC-Coupled to Laser Diode

• Programmable Modulation Current: 5mA to 60mA

• Programmable Bias Current: 1mA to 100mA

• Enable/Disable Control

• Typical Rise/Fall Times of 60ps

• Automatic Optical Average Power Control

• Supply Current of 33mA at 3.3V

3.3V Operation

SET

CLR

MUX

DATA+

APC

DATA-

CLK+

CLK-

ENABLE

BIAS

IOUT+ IOUT-

MODSET

BIASMAX

CAPC APCSET

FAIL

LATCH

1nF

DISABLE

SLWSTRT

• SDH/SONET at 622Mb/s, 1.244Gb/s,

2.488Gb/s, 3.125Gb/s

• Full-Speed Fibre Channel (1.062Gb/s)

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

VSC7938

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

Page 2 G52349-0, Rev 3.0

01/20/01

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

Internet: www.vitesse.com

Electrical Characteristics

Table 1: AC Specifications

AC specifications are guaranteed by design an d ch aracterization. Typical values are for 3.3V.

NOTES:(1) Measured with 622Mb/s 0-1 pattern, LATCH=high. (2) PWD = (wider pulse - narrower pulse) / 2).

Table 2: DC Specifications

NOTES: (1) Both I

BIAS

and I

MOD

will turn off if any of the current set pins are grounded. (2) Assumes laser diode to monitor diode transfer func-

tion does not change with temp erature.

Symbol Parameter Min Typ Max Units Conditions

Input Latch Setup Time 100 ps LATCH=high

Input Latch Hold Time 100 ps LATCH=high Enable/Start-up Delay 250 ns

Output Rise Time 60 80 ps 20% to 80%

Output Fall Time 60 80 ps 20% to 80% PWD Pulse Width Distortion 10 50 ps See Notes 1, 2 CID

MAX

Maximum Consecu tive Identical Digits 80 bits

Jitter Generation 7 20 ps

p-p

Jitter BW=12kHz to 20MHz, 0-1 pattern.

Symbol Parameter Min Typ Max Units Conditions

Supply Current TBD 45 mA

MODSET

=7.3kΩ

BIASMAX

=4.8kΩ

BIAS

and I

MOD

excluded

=5V

BIAS

Bias Current Range 1 100 mA Voltage at BIAS pin=(VCC-1.6)

BIAS-OFF

Bias Off Current 100 µA

ENABLE=low or DISABLE=high

(1)

BIAS

Bias Current Stability

230

ppm/°C

APC Open loop. I

BIAS

=100mA

900 APC Open loop. I

BIAS

=1mA

Bias Current Absolute Accuracy ±15 % Refers to part-to-part variation

Monitor Diode Reverse Bias Voltage 1.5 V

Monitor Diode Reverse Current Range 18 1000 µA

Monitor Diode Bias Setpoint Stability

-480 -50 480

ppm/°C

IMD=1mA

(2)

90 IMD=18µA

(2)

Monitor Diode Bias Absolute Accuracy -15 15 % Refers to part-to-part variation

MOD

Modulation Curren t Rang e 5 60 mA

MOD-OFF

Modulation Off Cur re nt 200 µA

ENABLE=low or DISABLE=high

(1)

Modulation Current Absolute Accuracy ±15 % See Note 2

Modulation Current Stability

-480 -50 480

ppm/°C

MOD

=60mA

250 I

MOD

=5mA

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

VSC7938

SONET/SDH 3.125Gb/s

Laser Diode Driver with Automatic Power Control

G52349-0, Rev 3.0 Page 3 01/20/01

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

Internet: www.vitesse.com

Table 3: PECL and TTL/CMOS Inputs and Outputs Specifications

Absolute Maximum Ratings

(1)

Power Supply Voltage (VCC)...............................................................................................................-0.5V to 6V

Current into BIAS.....................................................................................................................-20mA to +150mA

Current into OUT+, OUT-...............................................................................................................................TBD

Current into MD.............................................................................................................................-5mA to +5mA

Current into FAIL

......................................................................................................................... -10mA to 30mA

Voltage at DATA+, DATA-, CLK+, CLK-, ENABLE, LATCH.........................................-0.5V to (V

+ 0.5V)

Voltage at APCFILT, MODSET, BIASMAX, APCSET, MD, FAIL

, SLWSTRT..........................-0.5V to +3.0V

Voltage at OUT+, OUT- ..................................................................................................... -0.5V to (V

+ 1.5V)

Voltage at BIAS .................................................................................................................. -0.5V to (V

+ 0.5V)

Continouous Power Dissipation (T

= +85°C, TQFP derate 20.8mW/°C above +85°C) .......................1350mW

Operating Junction Temperature Range...................................................................................... -55°C to +150°C

Storage Temperature Range ........................................................................................................ -65°C to +165°C

NOTE: (1) CAUTION: Stresses listed under “Absolute Maximum Ratings” may be applied to devices one at a time without caus-

ing permanent damage. Functionality at or above the values listed is not implied. Exposure to these values for extended periods may affect device reliability.

Recommended Operating Conditions

Positive Voltage Rail (VCC)............................................... ......................................................+3.135V to +5.25V

Negative Voltage Rail (GND) ............................................................................................................................ 0V

Modulation Current (I

MOD

)

(1)

.......................................................................................................................30mA

Ambient Temperature Range (T

).................................................................................................-40°C to +85°C

NOTE: (1) VCC = 3.3V, I

BIAS

= 60mA.

Symbol Parameter Min Typ Max Units Conditions

Differential Input Voltage 100 1600 mV

p-p

(DATA+)-(DATA-)

ICM

Common-Mode Input V oltage

1.49

VCC -

1.32

VCC V

V PECL Compatible

Clock and Data Input Current -1 10 µA

TTL Input High Voltage (ENABLE, LATCH)

2.0 V

TTL Input Low Voltage (ENABLE, LATCH)

0.8 V

TTL Output High Voltag e (FAIL

)2.4

0.3

V Sourcing 50µA

TTL Output Low Voltage (FAIL) 0.1 0.44 V Sinking 100µA

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

VSC7938

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

Page 4 G52349-0, Rev 3.0

01/20/01

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

Internet: www.vitesse.com

Bare Die Descriptions

Figure 1: Pad Assignments

VSC7938

Die Size: 1773µm x 2233µm (0.0698" x 0.0879") Die Thickness: 625

µm (0.0246")

Pad Pitch: 115µm (0.0045") Pad Size: 95µm x 95µm (0.0037" x 0.0037")

Pad to Pad Clearance: 20µm (0.0008

") Pad Passivation Opening: 95µm x 95µm (0.0037" x 0.0037") Scribe Size: 75µm (0.0030")

Pad 10

CLK-

Pad 9 CLK+

Pad 8 VCC1

Pad 7 GND1

Pad 6 VCC1

Pad 5 DATA-

Pad 4

DATA+

Pad 3 VCC1

Pad 2 GND1

Pad 1 GND2

Pad 48

VCC2

Pad 47

BIASMAX

µm

(0.0008")

2233

µm

(0.0879")

1773

µm (0.0698")

µm

(0.0030")

Pad 46

MODSET

Pad 45

GND2

Pad 44

APCSET

Pad 43

AUTSEL

Pad 42

GND2

Pad 41

PB_GND

Pad 40

GND3

Pad 39

PB_GND

Pad 38

CAPC

Pad 37

VCC3

Pad 36

GND3

Pad 12

GND1

Pad 13 LATCH

Pad 14 ENABLE

Pad 15

DISABLE

Pad 16

GND1

Pad 17

SLWSTRT

Pad 18

VCC1

Pad 19

FAIL

Pad 20

GND4

Pad 21

PB_GND

Pad 22

APCFILT

Pad 23

GND4

Pad 24

VCC4

Pad 25

BIAS

Pad 11

VCC1

Pad 27

VCC4

Pad 28

DB_OUT+

Pad 29

OUT+

Pad 30

OUT-

Pad 31

DB_OUT-

Pad 32

VCC4

Pad 33 GND4

Pad 34

GND3

Pad 35

Pad 26

PB_GND

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

VSC7938

SONET/SDH 3.125Gb/s

Laser Diode Driver with Automatic Power Control

G52349-0, Rev 3.0 Page 5 01/20/01

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

Internet: www.vitesse.com

Table 4: Pad Coordinates

Signal

Name

Pad

Number

Coordinates (µm)

Signal

Name

Pad

Number

Coordinat es (µm)

X Y X Y

GND2 1 1613.55 1863.475 BIAS 25 159.45 368.475 GND1 2 1414.525 2073.55 PB_GND 26 369.525 159.45 VCC1 3 1289.525 2073.55 VCC4 27 484.525 159.45 DATA+ 4 1 174.525 2073.55 DB_OUT+ 28 599.525 159.45 DATA- 5 1059.525 2073.55 OUT+ 29 714.525 159.45 VCC1 6 944.525 2073.55 OUT- 30 829.525 159.45 GND1 7 829.525 2073.55 DB_OUT- 31 944.525 159.45 VCC1 8 714.525 2073.55 VCC4 32 1059.525 159.45 CLK+ 9 599.525 2073.55 GND4 33 1174.525 159.45 CLK- 10 484.525 2073.55 GND3 34 1289.525 159.45 VCC1 11 369.525 2073.55 MD 35 1404.525 159.45 GND1 12 159.45 1863.475 GND3 36 1613.55 368.475 LATCH 13 159.45 1748.475 VCC3 37 1613.55 483.475 ENABLE 14 159.45 1633.475 CAPC 38 1613.55 598.475 DISABLE 15 159.45 1518.475 PB_GND 39 1613.55 713.475 GND1 16 159.45 1403.475 GND3 40 1613.55 828.475 SLWSTRT 17 159.45 1288.475 PB_GND 41 1613.55 943.475 VCC1 18 159.45 1058.475 GND2 42 1613.55 1058.475 FAIL

19 159.45 1058.475 AUTSEL 43 1613.55 1173.475 GND4 20 159.45 828.475 APCSET 44 1613.55 1288.475 PB_GND 21 159.45 828.475 GND2 45 1613.55 1403.475 APCFILT 22 159.45 598.475 MODSET 46 1613.55 1518.475 GND4 23 159.45 598.475 BIASMAX 47 1613.55 1633.475 VCC4 24 159.45 483.475 VCC2 48 1613.55 1748.475

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