Datasheet VSC7926W, VSC7926KF, VSC7926KFL Datasheet (VITESSE)

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

VSC7926

SDH/SONET 2.5Gb/s Laser Diode Driver

G52188-0, Rev 3.0 Page 1
04/05/01

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

Tel: (800) VITESSE • FAX: [phone] • Email: [e-mail]

Internet: www.vitesse.com

Features

General Description

The VSC7926 is a single 5V supply, 2.5Gb/s laser diode driver with direct acce ss to the laser modulation
and bias FETs. Laser bias and modulation currents are set by external components allowing precision monitor­ing and setting of the current levels. Data density outputs are provided to allow the user to adjust the laser bias
in high unbalanced data applications. Clock and data inputs are differentially terminated to 50

Ω.

Applications

• SDH/SONET @ 622Mb/s, 1.244Gb/s, 2.488Gb/s

• Full Speed Fibre Channel (1.062Gb/s)

VSC7926 Block Diagram

• Rise Times of Less Than 100ps

• High-Speed Operation
(Up to 2.5Gb/s NRZ Data)

• Differential Inputs

• Single Supply

• Direct Access to Modulation and Bias FETs

• Data Density Monitors

• On-Chip Reclocking Register

DIN

DINTERM*

50 Ω

MK

NMK

IBIAS

NIOUT

IOUT

MIP

VIP

VIB

MIB

DQ

DCC

**

**On Die Components

I

MOD

I

BIAS

50 Ω

**

NDIN

CLK

50 Ω

**

50 Ω

**

NCLK

CLKTERM*

*Terminated to Off-chip Capacitor

DCC

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

VSC7926

SDH/SONET 2.5Gbits /sec

Laser Diode Driver

Page 2 G52188-0, Rev 3.0

04/05/01

© VITESSE SEMICONDUCTOR CORPORATION • 741 Ca ll e Pl an o • Camarillo, CA 93012

Tel: (800) VITESSE • FAX: [phone] • Email: [e-mail]

Internet: www.vitesse.com

Table 1: Signal Pin Reference

Table 2: Absolute Maximum Ratings

Table 3: High Speed Inputs and ECL Outputs

Signal Type Level # Pins Description

DIN, NDIN In 2 Data Input and Data Reference
DINTERM Ref DC 1 Data Termination
CLKTERM Ref DC 1 Clock Termination
MK, NMK Out ECL 2 Data Density Differential Outputs
NIOUT Out 1 Laser Modulation Current Output (Complementary)
IOUT Out 1 Laser Modulation Current Output (To Laser Cathode)
VSS Pwr Pwr 3 Negative Voltage Rail
GND Pwr Pwr 5 Positive Voltage Rail
VIP In DC 1 Modulation Gate Node
MIP In DC 1 Modulation Source Node
VIB In DC 1 Bias Gate Node
MIB In DC 1 Bias Sour ce Node
IBIAS Out DC 1 Laser Bias Output (To Laser Cathode)
CLK, NCLK In 2 Clock Input and Clock Reference
DCC In DC 1 Duty Cycle Control, Leave Floating
T otal Pin s 24

Symbol Rating Limit

V

SS

Negative Power Supply Voltage VCC to -6.0V

T

j

Maximum Junction Temperature -55°C to + 125°C

T

stg

Storage Temperature -65°C to +150°C

Symbol Parameter Min Max Units Conditions

V

IN

Differential Input Voltage Swing 500 1000 mV

V

CM

Differential Input Common Mode Range -2.3 -1.3 V VSS = -5.2V

V

OH

ECL Output High Voltage -1200 mV 50Ω to -2.0V

V

OL

ECL Output Low Voltage -1600 mV 50Ω to -2.0V

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

VSC7926

SDH/SONET 2.5Gb/s Laser Diode Driver

G52188-0, Rev 3.0 Page 3
04/05/01

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

Tel: (800) VITESSE • FAX: [phone] • Email: [e-mail]

Internet: www.vitesse.com

Table 4: Recommended Operating Conditions

NOTES: (1) Lower limit of specification is ambient temperature and upper limit is case temperature. (2) See “Calculation of the

Maximum Case Temperature” section in this data sheet for detailed maximum temperature calculations.

Table 5: Power Dissip atio n

Table 6: Laser Driver DC Electrical Specifications

Table 7: Laser Driver AC Electrical Specifications

Table 8: Package Thermal Specifications

Symbol Parameter Min Typ Max Units Conditions

GND Positive Voltage Rail - 0 - V
VSS Negative Voltage Rail -5.5 -5.2 -4.9 V
Tc

l

Operational Temperature

(1)

-40 - 85

(2)

°C Power dissipation = 1.25W

T

J

Junction Temperature - - 125 °C

Symbol Parameter Min Typ Max Units Conditions

I

VSS

Power Supply Current (VSS) - - 220 mA VSS = -5.5, I

MOD

= I

BIAS

= 0mA

P

D

T otal Po wer Dissipatio n - - 1210 mW

V

SS

= -5.5, I

MOD

= I

BIAS

= 0mA,

R

LOAD

= 25Ω to GND

P

DMAX

Maximum Power Dissipation - - 1815 mW

V

SS

= -5.5, I

MOD

= 60mA,

I

BIAS

= 50mA, I

OUT

= 0V

Symbol Parameter Min Typ Max Units Conditions

I

BIAS

Programmable Laser Bias Current 2 - 50 mA

I

MOD

Programmable Modulation Current 2 - 60 mA

V

IB

Laser Bias Control Voltage - -

V

SS

+

2.1

VI

BIAS

= 50mA

V

IP

Laser Modulation Control Voltage - -

V

SS

+

2.1

VI

MOD

= 60mA

V

OCM

Output Voltage Compliance

GND

-2.5V

--VV

SS

= -5.2V

Symbol Parameter Min Typ Max Units Conditions

tR t

F

Output Rise and Fall Times - - 100 ps

25Ω load, 20%-80%,
15mA < I

MOD

< 60 mA,

I

BIAS

= 40mA

t

SU

Setup Data to Clock Setup Time - 50 - ps

t

H

Hold Time - 50 - ps

Symbol Parameter Min Typ Max Units Conditions

θ

JCC

Thermal Resistance from Junction-to-Case - 25 - °C/W Ceramic Package

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

VSC7926

SDH/SONET 2.5Gbits /sec

Laser Diode Driver

Page 4 G52188-0, Rev 3.0

04/05/01

© VITESSE SEMICONDUCTOR CORPORATION • 741 Ca ll e Pl an o • Camarillo, CA 93012

Tel: (800) VITESSE • FAX: [phone] • Email: [e-mail]

Internet: www.vitesse.com

Calculation of the Maximum Case Temperature

The VSC7926 is designed to operate with a maximum junction temperature of 125°C. The rise from the
case to junction is determined by the power dissipation of the device . The power dissipation is determined by
the V

SS

current plus the operating I

MOD

and I

BIAS

currents.

The power of the chip is determined by the following formula:

P

D

= (-VSS * ISS) + ((V

IOUT – VSS

) * I

MOD

) + ((V

IBIAS – VSS

) * I

BIAS

)

For example with:

V

SS

=-5.2V

I

MOD

=40mA

I

BIAS

=20mA

V

IBIAS

=-2.0V

V

IOUT

=-2.0V

P

D

= (-5.2 * 220mA) + ((5.2 - 2.0) * 40mA) + ((5.2-- 2.0) * 20mA)

P

D

= 1144mW + 128mW + 64mW = 1.336W

The thermal rise from junction to case is

θ

JC

* PD. For the ceramic package, θ

JCC

= 25°C/W. Thus the ther-

mal rise is:

25°C/W * 1.336W = 33.4°C

The maximum case temperature is:

125°C – 33.4°C = 91.6°C

The absolute maximum power dissipation of the device is at:

V

SS

=-5.5V

I

MOD

=60mA

I

BIAS

=50mA

V

IBIAS

=0V

V

IOUT

=0V

P

D

= (5.5 * 220mA) + (5.5 * 60mA) + (5.5mA * 50mA)

P

D

= 1.815W

This will net a maximum junction to case thermal rise of: 1.815W * 25°C/W = 45.4°C

This situation will allow maximum case temperature of: 125°C – 45.4°C = 79.6°C

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

VSC7926

SDH/SONET 2.5Gb/s Laser Diode Driver

G52188-0, Rev 3.0 Page 5
04/05/01

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

Tel: (800) VITESSE • FAX: [phone] • Email: [e-mail]

Internet: www.vitesse.com

Figure 1: Control Signals VIP and VIB

Figure 2: Simplified Output Structure

50 mA

60 mA

I (MIB)

I (MIP)

VIP

VIB

2.1V

2.1V

Typical Bias Current v.s. Bias Voltage

Typical Modulation Current v.s. Modulation Voltage

X

XXX

X

X

NIOUT IOUT

X

IBIAS

OUTPUT
DIFF
PAIR

VIB

MIB

MIP

VIP

I

MOD

I

BIAS

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

VSC7926

SDH/SONET 2.5Gbits /sec

Laser Diode Driver

Page 6 G52188-0, Rev 3.0

04/05/01

© VITESSE SEMICONDUCTOR CORPORATION • 741 Ca ll e Pl an o • Camarillo, CA 93012

Tel: (800) VITESSE • FAX: [phone] • Email: [e-mail]

Internet: www.vitesse.com

Figure 3: Pad Assignments for VSC7926 Die

PAD 25

PAD 24

PAD 23

PAD 22

PAD 21

PAD 20

PAD 19

PAD 18

VIB

GND0

OUT

OUT

GND0

GND0

NOUT

IBIAS

PAD 1

PAD 34 PAD 33 PAD 32 PAD 31 PAD 30 PAD 29 PAD 28 PAD 27 PAD 26

DCC VSS VSS VSS VSS VIP MIP MIP MIB

PAD 2

PAD 3

PAD 4

PAD 5

PAD 6

PAD 7

PAD 8

NDIN

DINT

DIN

DINT

CLOCKT

CLOCK

CLOCKT

NCLOCK

PAD 9 PAD 10 PAD 11 PAD 12 PAD 13 PAD 14 PAD 15 PAD 16 PAD 17

VSS VSS GND GND GND GND GND NMARK MARK

120µm

120

150µm

30µm

1720µm

1620µm

1720µm

1620µm

50µm

50µm

50µm

50µm

Die Size: 1620µm x 1620µm
Actual Die Size: 1720µmx1720µm (after the di e ar e cut up)
Pad Size: 120µm x 120µm
Pad Pitch: 150µm
Space Between Pads:30µm

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

VSC7926

SDH/SONET 2.5Gb/s Laser Diode Driver

G52188-0, Rev 3.0 Page 7
04/05/01

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

Tel: (800) VITESSE • FAX: [phone] • Email: [e-mail]

Internet: www.vitesse.com

Pin Diagram for 24-Pin Ceramic Package

1

2

3

4

5

6

78910

11 12

13

14

15

16

17

18

24 23 22 21 20 19

NDIN

DIN

DINTERM

CLKTERM

CLK

NCLK

VIB

GND

IOUT

GND

NIOUT

IBIAS

VSS

GND

GND

GND

MK

MK

DCC

VSS

VSS

VIP

MIP

MIB

Note: Package li d and bottom heat spreader are electrically

connected to GND within the package.

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

VSC7926

SDH/SONET 2.5Gbits /sec

Laser Diode Driver

Page 8 G52188-0, Rev 3.0

04/05/01

© VITESSE SEMICONDUCTOR CORPORATION • 741 Ca ll e Pl an o • Camarillo, CA 93012

Tel: (800) VITESSE • FAX: [phone] • Email: [e-mail]

Internet: www.vitesse.com

Package Information - 24-Pin Ceramic Package (Formed Leads)

Top View

Side View

NOTES:

Drawing not to scale.
Package #: 101-300-7, Issue #:1

1

2

3

4

5

6

78910

11 12

13

14

15

16

17

18

24 23 22 21 20 19

INDEX

A

E

A

D

I

C

G

F

H

J

B

Key mm In

A 9.5 0.374
B 7.7 0.303
C 2.0 0.079
D1.27 0.050
E0.30 0.012

F 1.7 0.067
G 0.6 0.024
H11.5 0.453

I 0.125 0.005
J8.51 0.335

Lid #: 101-303-1, Issue #:1

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

VSC7926

SDH/SONET 2.5Gb/s Laser Diode Driver

G52188-0, Rev 3.0 Page 9
04/05/01

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

Tel: (800) VITESSE • FAX: [phone] • Email: [e-mail]

Internet: www.vitesse.com

Package Information - 24-Pin Ceramic Package (Straight Leads)

Top View

Side View

NOTES:

Drawing not to scale.
Package #: 101-000-0 Issue #:1

1

2

3

4

5

6

78910

11 12

13

14

15

16

17

18

24 23 22 21 20 19

INDEX

A

E

A

D

I

B

HC

C

F

G

Key mm In

A 9.5 0.374
B 7.7 0.303
C 5.8 .230
D1.27 0.050
E0.30 0.012

F 1.7 0.067
G 0.6 0.024
H9.53 0.375

I 0.125 0.005
J8.51 0.335

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

VSC7926

SDH/SONET 2.5Gbits /sec

Laser Diode Driver

Page 10 G52188-0, Rev 3.0

04/05/01

© VITESSE SEMICONDUCTOR CORPORATION • 741 Ca ll e Pl an o • Camarillo, CA 93012

Tel: (800) VITESSE • FAX: [phone] • Email: [e-mail]

Internet: www.vitesse.com

Ordering Informatio n

The order number for this product is formed by a combination of the device number, and package style.

Notice

Vitesse Semiconductor Corporation (“Vitesse”) provides this document for informational purposes only. This document contains pre-production
information about Vitesse products in their conce pt, development and/or testi ng phase. All information in t his document, including de scri ptions of
features, functions, performan ce, technical specifications and availability, is s ubject to change without notice at any time. Nothing contained in this
document shall be co nstru ed as e xten ding an y w arran ty or pr omise , e xpress or imp lied , that any Vitesse product wi ll b e av ail able as described or
will be suitable for or will accompli sh any particular task.

Vitesse products are not intended for use in life support applia nc es, devices or systems. Use of a Vitesse product in such applications without writ­ten consent is prohibited.

VSC7926

XX

Device Type

VSC7926: 2.5Gb/s Laser Diode Driver

Package Style

KF: (Ceramic - Straight Leads)
KFL: (Ceramic- Formed Leads)

W: Dice Waffle Pack