VITESSE VSC7928X, VSC7928RA Datasheet

Preliminary Da ta Sheet

VITESSE

SEMICONDUCTOR CORPORATION

VSC7928

SONET/SDH 3.2Gb/s Laser Diode Driver

Features Applications

• Rise Times Less Than 100ps

• High Speed Operation
(Up to 3.2Gb/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 Monitors

• On-chip Reclocking Register

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

• On-chip 50

Ω Input Termination: Clock and Data

• Enhanced Pinout

• SONET/SDH @ 622Mb/s, 1.244Gb/s,

2.488Gb/s, and 3.125Gb/s

• Full Speed Fibre Channel (1.062Gb/s)

General Description

The VSC7928 is a single 5V supply, 3.2Gb/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.

VSC7928 Block Diagram

MK

NMK

DIN

DINTERM*

NDIN

CLK

CLKTERM*

NCLK

*Terminated to Off-chip Capacitor

**On Die Components

G52246-0, Rev 3.0 Page 1
04/05/01

**

50 Ω

**

50 Ω

**

50 Ω

**

50 Ω

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

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

DQ

M
U
X

VIP

VIB

SEL

Internet: www.vitesse.com

DCC

MIP

I

MOD

MIB

IOUT

NIOUT

IBIAS

I

BIAS

VITESSE

SEMICONDUCTOR CORPORATION

Preliminary Data Sheet

SONET/SDH 3.2Gb/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
VSS Pwr Pwr 2 Negative Voltage Rail
GND Pwr Pwr 5/6
VIP In DC 1 Modulation Gate Node
MIP In DC 1 Modulation Source 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
GND/NC Pwr DC 7
T otal Pin s

NOTE: (1) Applicable to 32-pin TQFP package only.

——24/32

— 1 Laser Modulation Current Output (Complementary)
— 1 Laser Modulation Current Output (To Laser Cathode)

(1)

Positive Voltage Rail

(1)

No connection (leave floating or connect to GND)

*

VSC7928

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
T
T

SS
J
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
Maximum Case Temperature” for detailed maximum temperature calculations.

Operational Temperature
Junction Temperature ——125 °C

(1)

-40 — 85

(2)

°C Power dissipation = 1.3W

Page 2 G52246-0, Rev 3.0

© VITESSE SEMICONDUCTOR CORPORATION • 741 Ca l le Pl an o • Camarillo, CA 93012

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

Internet: www.vitesse.com

04/05/01

Preliminary Da ta Sheet

VITESSE

SEMICONDUCTOR CORPORATION

VSC7928

SONET/SDH 3.2Gb/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

CM

= -2.0V

Differential Input Common Mode Range -2.3 — -1.3 V VSS = -5.2V
ECL Output High Voltage -1200 — — mV 50Ω to -2.0V
ECL Output Low Voltage — — -1600 mV 50Ω to -2.0V
On-Chip Terminations 35 — 65 Ω

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) — 80 120 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

V

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 Voltag e ——

Output Voltage Compliance —

GND -

3V

SS

2.1

V

SS

2.1

— VV

+

VI

VI

BIAS

MOD

SS

= 50mA

= 60mA

= -5.2V

= I

= I

BIAS

BIAS

=

=

MOD

MOD

= 25Ω to GND,

T able 8: Laser Driver AC Electrical Specifications

Symbol Parameter Min Typ Max Units Conditions

25Ω load, 20%-80%,

tR, t

F

t

SU

t

H

G52246-0, Rev 3.0 Page 3
04/05/01

Output Rise and Fall Times ——100 ps

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

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

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

Internet: www.vitesse.com

20mA < I

= 60mA

I

BIAS

—
—

MOD

< 60mA,