Datasheet SY88902 Datasheet (MICREL)

LASER DIODE
DRIVER WTIH
OUTPUT ENABLE

SY88902

FEATURES

■ Up to 1.25Gbps operation

■ 25mA peak drive current

■ Separate modulation control

■ Separate output enable for laser safety

■ Differential inputs for data

■ 75KΩ input pulldown resistor

■ Single power supply

■ Designed for use with SY88903 and SY88904

■ Available in a tiny 10-pin (3mm) MSOP

PIN CONFIGURATIONS

1/EN

D

IN

2

/D

IN

V

REF

R

SET

MSOP

3

K10-1

4
5

10 V

9
8
7
6

CC

OUT
/OUT

GND
GND

DESCRIPTION

The SY88902 is a high speed current switch for driving
a semiconductor laser diode in optical transmission
applications. The output current, or modulation current
IMOD, is DC current controlled by IRSET, current through
the resistor RSET. The output OUT is HIGH when output
enable is HIGH.

The device incorporates complementary open collector
outputs with a capability of driving peak current of 25mA.
The resistor REXT must be placed between /OUT and
VCC to dissipate the worst case power. RSER is
recommended to compensate for laser diode matching
issues.

The SY88902 utilizes the high performance bipolar
ASSET™ technology.

APPLICATIONS

■ 1.25Gbps Gigabit Ethernet

■ 531Mbps and 1062Mbps Fibre Channel

■ 622Mbps SONET

■ Gigabit Interface Converter

BLOCK DIAGRAM

D

DIN

EN

VCC

REXT

OUT

OUT

RSER

Internal Logic

IN

IMOD

to Laser Diode

BIAS

Control

40X

VCC

Modulation Control

GND

VEE

VREF

RSET

RSET

Rev.: C Amendment: /1

1

Issue Date: July 2000

Micrel

SY88902

PIN NAMES TRUTH TABLE

Pin Function

CC Most positive power supply input, +5V for PECL

V

operation.

GND Ground

IN, /DIN These differential PECL 100K compatible inputs

D

receive NRZ data.

/EN This PECL 100K compatible input enables

Laser Driver. Modulation current goes to zero
when asserted HIGH.

OUT, /OUT Open collector outputs from the modulation

buffer drive these differential current outputs.
VREF Voltage reference for use with RSET.
RSET An external resistor sets up the source current

for modulation Imod.

ABSOLUTE MAXIMUM RATINGS

(1)

D D /EN OUT

LHLHL
HLLLH
XXHHL

NOTES:

1. L = LOW, H = HIGH, X = don't care

OUT = OmA

2. H = I

(1)

(2)

/OUT

Symbol Rating Value Unit

VCC Power Supply Voltage 0 to +7.0 V
VI Input Voltage 0 to VCC V
IO Output Current 25 mA
TA Operating Temperature Range 0 to +85 °C
Tstore Storage Temperature Range –55 to +125 °C
P

tot Power Dissipation 250 mW

NOTE:

1. Permanent device damage may occur if ABSOLUTE MAXIMUM RATINGS are exceeded. This is a stress rating only and functional operation is not implied
at conditions other than those detailed in the operational sections of this data sheet. Exposure to ABSOLUTE MAXIMUM RATlNG conditions for extended
periods may affect device reliability.

OPERATIONING CONDITIONS

(1)

Symbol Rating Value Unit

VCC Power Supply Voltage +4.5 to +5.5 V
REXT Resistor to Dissipate Power 10 to 50 Ω
RSER Laser Diode Serial Resistor 0 to 50 Ω
RSET Resistor to Adjust Current 1500 to 50,000 Ω
ΘJA Thermal Resistance of Package to Ambient

OUT Capacitance on OUT + /OUT 2.5 typical pf

C

(2)

206 °C/W

NOTES:

1. The voltage drop across REXT and RSER plus Laser Diode should not be greater than 2V.

2. Still air without heatsink.

2

Micrel

SY88902

DC ELECTRICAL CHARACTERISTICS

GND = 0V; VCC = +5.0V ±10%; TA = 0˚C to + 85˚C

TA = 0°CTA = +25°CTA = +85°C

Symbol Parameter Min. Typ. Max. Min. Typ. Max. Min. Typ. Max. Unit

IH Input HIGH Voltage

V

(DIN, /DIN, /EN)

IL Input LOW Voltage VCC-1810 — VCC-1475 VCC-1810 — VCC-1475 VCC-1810 — VCC-1475 mV

V

(DIN, /DIN, /EN)

VREF Reference Voltage — 3.12 ——3.00 ——2.80 — V

IL Input LOW Current

I

(DIN, /DIN, /EN)

IH Input HIGH Current ——100 ——100 ——100 uA

I

(DIN, /DIN, /EN)

ICC Supply Current

OL Output LOW Current ——500 ——500 ——500 uA

I

(2)

(/EN = HIGH)
IOUT Modulation Current 5 15 25 5 15 25 5 15 25 mA
IRSET Modulation Control 0.125 — 0.625 0.125 — 0.625 0.125 — 0.625 mA

RSET =IOUT/IRSET 30 38 44 30 38 44 30 38 44 —

A

NOTES:

1. VI = VIL(Min.)

2. IMOD = 25mA.

VCC-1165 — VCC-880 VCC-1165 — VCC-880 VCC-1165 — VCC-880

(1)

0.5 —— 0.5 —— 0.5 ——uA

— 16 25 — 16 25 — 16 25 mA

mV

AC ELECTRICAL CHARACTERISTICS

(1)

IMOD =10mA; GND = 0V; VCC = +5V ±10%; TA = 0˚C to + 85˚C

TA = 0°CTA = +25°CTA = +85°C

Symbol Parameter Min. Typ. Max. Min. Typ. Max. Min. Typ. Max. Unit Conditions

pd D Propagation Delay ——1000 — 500 1000 ——1000 ps IMOD = 10mA

t

DIN - OUT

pd EN Propagation Delay ——1000 — 450 1000 ——1000 ps IMOD = 10mA

t

/EN - OUT

r Rise/Fall Time — 200 ——200 ——200 — ps

t
tf (20% to 80%)

OR Output Current Ringing

I

NOTES:

1. REXT = RSER = 50Ω ±1%, RSER connects to VCC directly without Laser Diode.

2. IOH = 5 to 25mA

(2)

——10 ——10 ——10 %

3

Micrel

OUT

V

CC

GND

SY88904

D

IN

D

IN

TX_FAULT

TX_DISABLE

LOS

OUT

GBIC Terminal

V

CC

OUT

TX_Out I

BIAS

EN

OC

PECL

LOSEN

MD

D

OUT

D

OUT

D

IN

D

IN

V

CC

GND

SY88902

SY88903

V

CC

GND

V

CC

I

BIAS SET

I

BIAS SET

I

LIMIT SET

Laser

Module

PECL

R

EXT

R

SER

–RX_DAT

+RX_DAT

TX_DISABLE

TX_FAULT

–TX_DATA

+TX_DAT

V

REF

R

SET

R

WIN

V

REF

LOS

V

CC

V

REF

V

CC

I

BIAS FB

V

CC

DET

V

REF

2meg

0.1µf

I

PIN SET

V

REF

RX_LOS

I

LIMIT SET

V

CC

LOS

LVL

APPLICATION EXAMPLE FOR 3-CHIP SET SOLUTION

SY88902

4

Micrel

OUT

V

CC

V

EE

SY88905

D

IN

D

IN

LOS

OUT

Gigabit EthernetTerminal

V

CC

OUT

I

BIAS

EN

LOSEN

MD

D

OUT

D

OUT

D

IN

D

IN

V

CC

V

EE

SY88902

SY88903

V

CC

V

CC

V

BIAS SET

I

BIAS SET

Laser

Module

PECL

R

EXT

R

SER

–RX_DAT

+RX_DAT

–TX_DATA

+TX_DAT

V

REF

R

SET

V

LVL

V

REF

LOS

IN

V

REF

I

BIAS FB

I

PIN SET

V

REF

RX_LOS

V

BB

V

CC

I

BIAS SET

V

PIN SET

GND

APPLICATION EXAMPLE FOR 3-CHIP SET SOLUTION

SY88902

5

Micrel

PERFORMANCE CURVES

30

25

20

15

(mA)

O

I

10

5

IO and

SY88902

R

SET

0.0

0.0

2.0K

PRODUCT ORDERING CODE

4.0K

R

SET

6.0K

(ohm)

8.0K 10K

12K

Ordering Package Operating

Code Type Range

SY88902KC K10-1 Commercial
SY88902KCTR K10-1 Commercial

6

Micrel

10 LEAD MSOP (K10-1)

SY88902

Rev. 00

7

Micrel

SY88902

MICREL-SYNERGY 3250 SCOTT BOULEVARD SANTA CLARA CA 95054 USA

TEL + 1 [phone] FAX + 1 [phone] WEB http://www.micrel.com

This information is believed to be accurate and reliable, however no responsibility is assumed by Micrel for its use nor for any infringement of patents or

other rights of third parties resulting from its use. No license is granted by implication or otherwise under any patent or patent right of Micrel Inc.

© 2000 Micrel Incorporated

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