MICREL SY88922KC

SDH/SONET 2.5Gbps
LASER DIODE DRIVER
FEATURES
■
■
■
■
■
■
■
■
DESCRIPTION
Up to 2.5Gbps operation
25mA peak drive current
Separate modulation control
Separate output enable for laser safety
Differential inputs for data
75KΩ input pulldown resistor
Designed for use with SY88923, SY88904 or SY88905
Available in a tiny 10-pin (3mm) MSOP
The SY88922 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
V CC to dissipate the worst case power. R SER is
recommended to compensate for laser diode matching
issues.
The SY88922 utilizes the high performance bipolar
ASSET™ technology.
APPLICATIONS
PIN CONFIGURATIONS
/EN 1
■
■
■
■
■
10 VCC
DIN 2
/DIN 3
SY88922
9 OUT
MSOP
K10-1
8 /OUT
VREF 4
7 GND
RSET 5
6 GND
1.25Gbps Gigabit Ethernet
531Mbps and 1062Mbps Fibre Channel
622Mbps SONET
Gigabit Interface Converter
2.5Gb/s SDH/SONET
BLOCK DIAGRAM
VCC
REXT
OUT
OUT
RSER
DIN
Internal Logic
DIN
IMOD
EN
BIAS
Control
to Laser Diode
40X
VCC
GND
Modulation Control
GND
RSET
VREF
RSET
Rev.: B
1
Amendment: /1
Issue Date: July 2000
SY88922
Micrel
TRUTH TABLE(1)
PIN NAMES
Pin
Function
VCC
Most positive power supply input, +5V for PECL
operation.
GND
Ground
DIN, /DIN
These differential PECL 100K compatible inputs
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.
D
D
/EN
OUT(2)
/OUT
L
H
L
H
L
H
L
L
L
H
X
X
H
H
L
NOTES:
1. L = LOW, H = HIGH, X = don't care
2. H = IOUT = 0mA
ABSOLUTE MAXIMUM RATINGS(1)
Symbol
Rating
Value
Unit
VCC
Power Supply Voltage
0 to +7.0
V
VI
Input Voltage
0 to VCC
V
IO
Output Current
TA
Operating Temperature Range
Tstore
Storage Temperature Range
Ptot
Power Dissipation
25
mA
0 to +85
°C
–55 to +125
°C
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
+4.5 to +5.5
V
VCC
Power Supply Voltage
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
113
°C/W
2.5 typical
pf
ΘJA
Thermal Resistance of Package to
COUT
Capacitance on OUT + /OUT
Ambient(2)
NOTES:
1. The voltage drop across REXT and RSER plus Laser Diode should not be greater than 2V.
2. Still air without heatsink.
2
SY88922
Micrel
DC ELECTRICAL CHARACTERISTICS
GND = 0V; VCC = +5.0V ±10%; TA = 0°C to + 85°C
TA = 0°C
Symbol
Parameter
TA = +25°C
Min.
Typ.
Max.
Min.
Typ.
TA = +85°C
Max.
Min.
Typ.
Max.
Unit
VIH
Input HIGH Voltage
(DIN, /DIN, /EN)
VCC–1165
—
VCC–880
VCC–1165
—
VCC–880 VCC–1165
—
VCC–880
mV
VIL
Input LOW Voltage
(DIN, /DIN, /EN)
VCC–1810
—
VCC–1475 VCC–1810
—
VCC–1475 VCC–1810
—
VCC–1475
mV
VREF
Reference Voltage
—
3.12
—
—
3.00
—
—
2.80
—
V
Current(1)
IIL
Input LOW
(DIN, /DIN, /EN)
0.5
—
—
0.5
—
—
0.5
—
—
uA
IIH
Input HIGH Current
(DIN, /DIN, /EN)
—
—
100
—
—
100
—
—
100
uA
ICC
Supply Current(2)
—
16
25
—
16
25
—
16
25
mA
IOL
Output LOW Current
(/EN = HIGH)
—
—
500
—
—
500
—
—
500
uA
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
ARSET
=IOUT/IRSET
30
38
44
30
38
44
30
38
44
—
NOTES:
1. VI = VIL(Min.)
2. IMOD = 25mA.
AC ELECTRICAL CHARACTERISTICS(1)
IMOD =10mA; GND = 0V; VCC = +5V ±10%; TA = 0°C to + 85°C
TA = 0°C
Symbol
Parameter
TA = +25°C
TA = +85°C
Min.
Typ.
Max.
Min.
Typ.
Max.
Min.
Typ.
Max.
Unit
tpd D
Propagation Delay
DIN - OUT
—
—
1000
—
500
1000
—
—
1000
ps
tpd EN
Propagation Delay
/EN - OUT
—
—
1000
—
450
1000
—
—
1000
ps
tr
tf
Rise/Fall Time
(20% to 80%)
—
—
160
—
110
160
—
—
160
ps
IOR
Output Current Ringing(2)
—
—
10
—
—
10
—
—
10
%
NOTES:
1. REXT = RSER = 25Ω ±1%, RSER connects to VCC directly without Laser Diode.
2. IOH = 5 to 25mA
3
Conditions
Load = 25Ω
SY88922
Micrel
PERFORMANCE CURVES
IO and RSET
30
25
IO (mA)
20
15
10
5
0.0
0.0
2.0K
4.0K
6.0K
RSET (ohm)
PRODUCT ORDERING CODE
Ordering
Code
Package
Type
Operating
Range
SY88922KC
K10-1
Commercial
SY88922KCTR
K10-1
Commercial
4
8.0K
10K
12K
SY88922
Micrel
APPLICATION EXAMPLE FOR 3-CHIP SET SOLUTION
GBIC Terminal
TX_DATA+
VCC
DIN
DIN
LOSOUT
EN
VREF
RSET
20kΩ
VREF
GND
SY88922
VCC
IBIAS
GND
SY88905
VCC
LOS
VCC
OUT
RSER
VCC
20kΩ
20kΩ
OUT
MD
IBIAS SET
IBIAS FB
IPIN SET
DIN
DIN
0.1µF
BLM21A102S
VCC
Laser
Module
The value of RSER
depends on the Laser Diode.
VCC
5
24Ω
LOSLVL
82Ω
LOSIN
EN
SY88923
VREF
130Ω
Laserdiode
REXT
1000pF
82Ω
68Ω
82Ω
Photodiode
130Ω
200Ω
130Ω
TX_DATA–
VCC
DOUT
DOUT
GND
0.1µF
68Ω
82Ω
ENABLE/DISABLE
RX_LOS
RX_DATA+
RX_DATA–
VCC
20kΩ
200Ω
130Ω
SY88922
Micrel
10 LEAD MSOP (K10-1)
Rev. 00
6
SY88922
Micrel
7
SY88922
Micrel
MICREL-SYNERGY
TEL
3250 SCOTT BOULEVARD SANTA CLARA CA 95054 USA
+ 1 (408) 980-9191
FAX
+ 1 (408) 914-7878
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
8