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SDH/SONET 2.5Gbps LASER DIODE DRIVER
SY88922
FEATURES
s s s s s s s s Up to 2.5Gbps operation 25mA peak drive current Separate modulation control Separate output enable for laser safety Differential inputs for data 75K input pulldown resistor Designed for use with SY88923, SY88904 or SY88905 Available in a tiny 10-pin (3mm) MSOP
DESCRIPTION
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 VCC to dissipate the worst case power. RSER is recommended to compensate for laser diode matching issues. The SY88922 utilizes the high performance bipolar ASSETTM technology.
PIN CONFIGURATIONS
/EN 1 DIN 2 /DIN 3 VREF 4 RSET 5 MSOP K10-1 10 VCC 9 OUT 8 /OUT 7 GND 6 GND
APPLICATIONS
s s s s s 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 DIN IMOD EN BIAS Control Internal Logic to Laser Diode
40X VCC GND GND RSET
Modulation Control
VREF
RSET
Rev.: B Amendment: /1
1
Issue Date: July 2000
Micrel
SY88922
PIN NAMES
Pin VCC GND DIN, /DIN /EN Function Most positive power supply input, +5V for PECL operation. Ground These differential PECL 100K compatible inputs receive NRZ data. This PECL 100K compatible input enables Laser Driver. Modulation current goes to zero when asserted HIGH. Open collector outputs from the modulation buffer drive these differential current outputs. Voltage reference for use with RSET. An external resistor sets up the source current for modulation Imod.
TRUTH TABLE(1)
D L H X D H L X /EN L L H OUT(2) H L H /OUT L H L
NOTES: 1. L = LOW, H = HIGH, X = don't care 2. H = IOUT = 0mA
OUT, /OUT VREF RSET
ABSOLUTE MAXIMUM RATINGS(1)
Symbol VCC VI IO TA Tstore Ptot Power Supply Voltage Input Voltage Output Current Operating Temperature Range Storage Temperature Range Power Dissipation Rating Value 0 to +7.0 0 to VCC 25 0 to +85 -55 to +125 250 Unit V V mA C C 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 VCC REXT RSER RSET JA COUT Power Supply Voltage Resistor to Dissipate Power Laser Diode Serial Resistor Resistor to Adjust Current Thermal Resistance of Package to Capacitance on OUT + /OUT Ambient(2) Rating Value +4.5 to +5.5 10 to 50 0 to 50 1500 to 50,000 113 2.5 typical Unit V C/W pf
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
SY88922
DC ELECTRICAL CHARACTERISTICS
GND = 0V; VCC = +5.0V 10%; TA = 0C to + 85C
TA = 0C Symbol VIH VIL VREF IIL IIH ICC IOL IOUT IRSET ARSET Parameter Input HIGH Voltage (DIN, /DIN, /EN) Input LOW Voltage (DIN, /DIN, /EN) Reference Voltage Input LOW (DIN, /DIN, /EN) Current(1) Min. VCC-1165 VCC-1810 -- 0.5 -- -- -- 5 0.125 30 Typ. -- -- 3.12 -- -- 16 -- 15 -- 38 Max. VCC-880 Min. VCC-1165 TA = +25C Typ. -- -- 3.00 -- -- 16 -- 15 -- 38 Max. Min. TA = +85C Typ. -- -- 2.80 -- -- 16 -- 15 -- 38 Max. VCC-880 VCC-1475 -- -- 100 25 500 25 0.625 44 Unit mV mV V uA uA mA uA mA mA --
VCC-880 VCC-1165 VCC-1475 VCC-1810 -- -- 100 25 500 25 0.625 44 -- 0.5 -- -- -- 5 0.125 30
VCC-1475 VCC-1810 -- -- 100 25 500 25 0.625 44 -- 0.5 -- -- -- 5 0.125 30
Input HIGH Current (DIN, /DIN, /EN) Supply Current(2) Output LOW Current (/EN = HIGH) Modulation Current Modulation Control =IOUT/IRSET
NOTES: 1. VI = VIL(Min.) 2. IMOD = 25mA.
AC ELECTRICAL CHARACTERISTICS(1)
IMOD =10mA; GND = 0V; VCC = +5V 10%; TA = 0C to + 85C
TA = 0C Symbol tpd D tpd EN tr tf IOR Parameter Propagation Delay DIN - OUT Propagation Delay /EN - OUT Rise/Fall Time (20% to 80%) Output Current Ringing(2) Min. -- -- -- -- Typ. -- -- -- -- Max. 1000 1000 160 10 Min. -- -- -- -- TA = +25C Typ. 500 450 110 -- Max. 1000 1000 160 10 Min. -- -- -- -- TA = +85C Typ. -- -- -- -- Max. 1000 1000 160 10 Unit ps ps ps % Load = 25 Conditions
NOTES: 1. REXT = RSER = 25 1%, RSER connects to VCC directly without Laser Diode. 2. IOH = 5 to 25mA
3
Micrel
SY88922
PERFORMANCE CURVES
IO and RSET 30
25
20
IO (mA)
15
10
5
0.0 0.0 2.0K
4.0K
6.0K
RSET (ohm)
8.0K
10K
12K
PRODUCT ORDERING CODE
Ordering Code SY88922KC SY88922KCTR Package Type K10-1 K10-1 Operating Range Commercial Commercial
4
SY88922
20k
68
68
VREF OUT DIN DIN
RSET
TX_DATA+
SY88922
EN
200
200
TX_DATA-
OUT
REXT
24
RSER
BLM21A102S
Laser Module
ENABLE/DISABLE
VCC
GND
VCC
APPLICATION EXAMPLE FOR 3-CHIP SET SOLUTION
GBIC Terminal
IBIAS
MD IBIAS SET
20k
The value of RSER depends on the Laser Diode.
SY88905
LOSOUT LOSIN
RX_LOS
IBIAS FB IPIN SET
20k
1000pF
VCC
Photodiode Laserdiode
VCC
VCC VCC
82 82
GND
VREF VCC
82
DIN DOUT DOUT
RX_DATA+ RX_DATA-
130 130
130
LOSLVL
0.1F
VCC
0.1F
VCC
GND
VREF
Micrel
20k
130
SY88923
DIN
82
EN
LOS
5
Micrel
SY88922
10 LEAD MSOP (K10-1)
Rev. 00
6
Micrel
SY88922
7
Micrel
SY88922
MICREL-SYNERGY
TEL
3250 SCOTT BOULEVARD SANTA CLARA CA 95054 USA
FAX
+ 1 (408) 980-9191
+ 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. (c) 2000 Micrel Incorporated
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