VITESSE VSC7927X, VSC7927KFRL, VSC7927KFL, VSC7927KF Datasheet

Preliminary Data Sheet

VITESSE

SEMICONDUCTOR CORPORATION

VSC7927

SONET/SDH 2.5Gb/s Laser Diode Driver

Features

• Rise Times of Less Than 100ps

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

• Differential or Single-Ended Inputs

• Single Supply

• ECL-Compatible Clock and Data Inputs

• Direct Access to Modulation and Bias FETs

• Data Density Monito rs

• On-Chip Reclocking Register

• On-Chip Mux for Clocked or Non-clocked Applications

• On-Chip 50

Ω Input Termination: Clock and Data

General Description

The VSC7927 is a single 5V supply, 2.5 Gb/s laser diode driver with direct access 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)

VSC7927 Block Diagram

DIN

DINTERM*

NDIN

CLK

CLKTERM*

NCLK

*Terminated to Off-chip Capacitor

**On Die Components

50 Ω

**

DQ

M U X

SEL

VIP

VIB

DCC

MK

NMK

MIP

I

MOD

MIB

IOUT

NIOUT

IBIAS

I

BIAS

G52201-0, Rev 3.0 Page 1 04/05/01

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

Internet: www.vitesse.com

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

SONET/SDH 2.5Gb/s Laser Diode Driver

Table 1: Signal Pin Reference

Signal Type Level # Pins Description

DIN, NDIN In ECL 2 Data Input and Data Reference, On-chip 50Ω Termination MK, NMK Out ECL 2 Data Density Differential Outputs NIOUT Out

IOUT Out — 1 Laser Modulation Current Output (to Laser Cathode) VSS Pwr Pwr 2 Negative Voltage Rail GND Pwr Pwr 5 Positive Voltage Rail VIP In DC 1 Modulation Gate Node MIP In DC 1 Modulatio n Sou r ce Node VIB I n DC 1 Bias Gate Node MIB In DC 1 Bias Source Node IBIAS Out DC 1 Laser Bias Output (To Laser Cathode) CLK, NCLK In ECL 2 Clock Input and Clock Reference, On-chip 50Ω Termination DINTERM In DC 1 Data Reference CLKTERM In DC 1 Clock Reference DCC In DC 1 Duty Cycle Control, Leave Floating SEL In DC 1 Clk/Non-clk Data Select T otal Pin s

—— 24

— 1 Laser Modulation Current Output (Complementary)

VSC7927

Table 2: Mux Select Logic Table

SEL Mode Select

V

SS

GND Non-clocked Data In

N/C Non-clocked Data In

Clocked Data In

Table 3: Absolute Maximum Ratings

Symbol Rating Limit

V

SS

T

J

T

STG

Negative Power Supply Voltage VCC to -6.0V Maximum Junction Temperature -55°C to + 125°C Storage Temperature -65°C to +150°C

Table 4: Recommended Operating Conditions

Symbol Parameter Min Typ Max Units Conditions

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

Cl

T

J

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

Operational Temperature Junction Temperature ——125 °C

Maximum Case Temperature” for detailed maximum temperature calculations.

(1)

-40 — 85

(2)

°C Power dissipation = 1.3W

Page 2 G52201-0, Rev 3.0

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

Internet: www.vitesse.com

04/05/01/01

Preliminary Data Sheet

VITESSE

SEMICONDUCTOR CORPORATION

VSC7927

SONET/SDH 2.5Gb/s Laser Diode Driver

Table 5: High Speed Inputs and ECL Outputs

Symbol Parameter Min Typ Max Units Conditions

V

IN

V

CM

V

OH

V

OL

V

IN

Single-ended Input Voltage Swing 300 — 1500 mVp-p V Differential Input Common Mode Range -2.3 — -1.3 V VSS = -5.2V ECL Output High Vol tag e -1200 ——mV 50Ω to -2.0V ECL Output Low Voltage ——-1600 mV 50Ω to -2.0V On-Chip Terminations 35 — 65 Ω

CM

Table 6: Power Diss ipat ion

Symbol Parameter Min Typ Max Units Conditions

= -5.5V, I

V

I

P

VSS

D

Power Supply Current (VSS) ——120 mA

Total Power Dissipation ——700 mW

SS

0mA, MK/NMK open circuit V

= -5.5V, I

SS

0mA, R

LOAD

MK/NMK terminated 50Ω to -2V

T able 7: Laser Driver DC Electrical Specifications

Symbol Parameter Min Typ Max Units Conditions

I

BIAS

I

MOD

V

IB

IP

OCM

Programmable Laser Bias Current 2 — 100 mA — Programmable Modulation Current 2 — 100 mA

V

+

Laser Bias Control Voltage ——

Laser Modulation Control Voltage ——

Output Voltage Compliance —

GND -

3V

SS

2.1

V

+

SS

2.1

— VV

—

VI

BIAS

MOD

SS

= 50mA

= 60mA

= -5.2V

= -2.0V

= I

MOD

BIAS

= I

MOD

= 25Ω to GND,

BIAS

=

T able 8: Laser Driver AC Electrical Specifications

Symbol Parameter Min Typ Max Units Conditions

25Ω load, 20%-80%,

tR, t

t

SU

t

H

F

Output Rise and Fall Times ——100 ps

Data to Clock Setup Time — 50 90 ps Hold Time 20 50 — ps

20mA < I

= 60mA

I

BIAS

— —

MOD

< 60mA,

Table 9: Package Thermal Specifications

Symbol Parameter Min Typ Max Units Conditions

θ

JCC

G52201-0, Rev 3.0 Page 3 04/05/01

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

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

Internet: www.vitesse.com

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

SONET/SDH 2.5Gb/s Laser Diode Driver

VSC7927

Calculation of the Maximum Case Temperature

The VSC7927 is designed to operate with a maximum junction temperature of 125°C. The rise from the case to junction is determined by the power dissip ation of the dev ice. The power dissipation is determine d by the V

current plus the operating I

SS

MOD

and I

BIAS

currents.

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

P

= (-VSS * ISS) + ((V

D

IOUT – VSS

) * I

MOD

For example with:

V

SS

I

MOD

I

BIAS

V

IBIAS

V

IOUT

P

D

P

D

=-5.2V =40mA =20mA =-2.0V =-2.0V

= (-5.2 * 150mA) + ((5.2 - 2.0) * 40mA) + ((5.2-- 2.0) * 20mA)

= 780mW + 128mW + 64mW = 972mW

) + ((V

IBIAS – VSS

) * I

BIAS

)

θ

The thermal rise from junction-to-case is

* PD. For the ceramic package, θ

JC

mal rise is:

25°C/W * 972W = 24.3°C

The maximum case temperature is:

125°C – 24.3°C = 100.7°C

The absolute maximum power dissipation of the device is at:

V

I

MOD

I

BIAS

V

IBIAS

V

IOUT

P

D

P

D

SS

=-5.5V =60mA =50mA =0V =0V

= (5.5 * 150mA) + (5.5 * 60mA) + (5.5mA * 50mA)

= 1.43W

This will net a maximum junction to case thermal rise of: 1.43W * 25°C/W = 35.8°C

This situation will allow maximum case temperature of: 35.8°C – 58°C = 89.2°C

= 25°C/W. Thus the ther-

JCP

Page 4 G52201-0, Rev 3.0

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

Internet: www.vitesse.com

04/05/01/01