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LASER DIODE CONTROLLER WITH APC
FEATURES
s DC bias current adjustable to 25mA s Buffered Loss-of-Signal output when used with SY88903 s Monitor Diode power control circuit s Designed for use with SY88902 and SY88903 s Single power supply s Available in 10-pin (3mm) MSOP
SY88905
DESCRIPTION
The SY88905 is an integrated Laser Diode controller for the SY88902 Laser Driver and SY88903 Laser Receiver that provides power control functions for a complete module solution. The SY88905 is designed to provide the laser diode with an independent DC threshold current (IBIAS) source to assure optimum laser diode performance. The SY88905 also provides buffered Loss-of-Signal (LOS) output in PECL level. The device is designed for fast and accurate calibration of the laser diode. Once the optimal operating point is determined and set for a specific laser diode, the threshold current (IBIAS) is designed to automatically compensate for laser diode aging and module temperature.
PIN CONFIGURATION
LOSIN 1 LOSOUT 2 GND 3 IBIAS 4 VCC 5 MSOP K10-1
10 VREF 9 IBIAS SET 8 IBIAS FB 7 6 IPIN SET MD
APPLICATIONS
s s s s s Controller for High Speed Optical Data Transmission 1.25Gbps Gigabit Ethernet 531 Mbps and 1062Mbps Fibre Channel 622Mbps SONET Gigabit Interface Converter
BLOCK DIAGRAM
LOSOUT VREF2
IBIAS
MD
LOSIN 40X VCC GND + VREF 2
VREF
IBIAS SET
IBIAS FB
IPIN
SET
Rev.: B
Amendment: /1
1
Issue Date: July 2000
Micrel
SY88905
PIN DEFINITIONS
Pin VCC GND LOSIN VREF IPIN SET LOSOUT IBIASFB IBIASSET MD IBIAS Type Power Power TTL Input Analog Output Analog Input PECL Output Analog Output Analog Input Analog Input Analog Input Positive Power supply Ground Loss-of-Signal Input from SY88903 Reference Voltage Adjustable, Resistor to VREF sets Monitor Diode Photo Current Reference Loss-of-Signal PECL output Monitor Diode Feedback Adjustable, Resistor to VREF sets the DC bias current for the Laser Diode Monitor Diode Connection DC bias current for the Laser Diode Description
ABSOLUTE MAXIMUM RATINGS(1) LOGIC DIAGRAM
Symbol VCC LOSIN LOSOUT, IPIN SET IBIASFB, IBIAS SET TA Tstore IPIN SET, IBIAS SET, IMD IBIASFB IBIAS IVREF Rating Power Supply Voltage Input Voltage Others; I/O Voltage Operating Temperature Range Storage Temperature Range Max. Sink Current Max. Source Current Max. Sink Current Max. Source Current Value 0 to +7.0 0 to VCC -0.3, VCC +0.3 0 to +85 -55 to +125 1 1 30 2 Unit V V V C C mA mA mA mA
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.
100H ECL DC ELECTRICAL(1)
VCC = +5V 10%
TA = 0C Symbol VOH VOL Parameter Output HIGH Voltage Output LOW Voltage Min. Max. TA = +25C Min. Max. TA = +85C Min. Max. Unit mV mV Condition 50 to VCC-2V 50 to VCC-2V
VCC - 1025 VCC - 880 VCC - 1025 VCC - 880 VCC - 1025 VCC - 880 VCC -1810 VCC -1620 VCC -1810 VCC -1620 VCC -1810 VCC-1620
NOTE: 1. 100H circuits are designed to meet the DC specifications shown in the table where transverse airflow greater than 500lfpm is maintained.
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Micrel
SY88905
DC ELECTRICAL CHARACTERISTICS
VCC = +5V 10%
TA = 0C Symbol ICC IBIAS SET IBIAS ABIAS VREF VPIN SET VBIAS SET IBIAS FB ABIAS FB
NOTE: 1. |IMD - IPIN SET| = 100A 2. |IBIAS FB| / |IMD - IPIN SET|
TA = +25C Min. -- -- 0.5 28 2.30 0.95 0.8 0.1 350 4 Typ. 28 -- -- 37 2.75 1.13 1.0 0.4 500 -- Max. 40 0.9 25 44 3.30 1.35 1.20 1.0 -- 14 40 0.9 25 44 3.30 1.35 1.20 1.0 -- 14
TA = +85C Min. Typ. Max. Unit -- -- 0.5 28 2.30 0.95 0.8 0.1 350 4 -- -- -- -- -- -- -- -- -- -- 40 0.9 25 44 3.30 1.35 1.20 1.0 -- 14 V V V V A mA mA mA =IBIAS / IBIAS SET IREF = -100A =VREF - VPIN SET =VREF - VBIAS SET IBIAS = 15mA Conditions No output load
Parameter Power Supply Current IBIAS SET Input Current IBIAS Output Current IBIAS Current Gain Reference Voltage VPIN SET Voltage Tracking VBIAS Voltage Tracking Current(1) Gain(2)
Min. -- -- 0.5 28 2.30 0.95 0.8 0.1 350 4
Typ. -- -- -- -- -- -- -- -- -- --
Max.
VCOMP BIAS Compliance Voltage Feedback Feedback
TTL DC ELECTRICAL CHARACTERISTICS
VCC = +5V 10%
TA = 0C Symbol VIH VIL IIH IIL VIK Parameter Input HIGH Voltage Input LOW Voltage Input HIGH Current Input LOW Current Input Clamp Voltage Min. 2.0 -- -- -- -- -- Max. -- 0.8 20 100 -0.3 -1.2 TA = +25C Min. 2.0 -- -- -- -- -- Max. -- 0.8 20 100 -0.3 -1.2 TA = +85C Min. 2.0 -- -- -- -- -- Max. -- 0.8 20 100 -0.3 -1.2 Unit V V A mA V Condition -- -- VIN = 2.7V VIN = VCC VIN = 0.5V IIN = -12mA
NOTE: 1. Individual product specifications over-ride general specifications.
DETAILED DESCRIPTION
The SY88905 is an integrated control circuit for laser diode modules intended for high-frequency fiber-optic applications. The device is designed to operate with the SY88902 laser diode driver providing Automatic Power Control (APC) which provides bias current control and monitor diode interface. The device also interfaces with the SY88903 high-speed limiting amplifier providing chatter-free Loss of Signal function. Laser Diode Supply Current The SY88905 provides the adjustable drive current for the laser diode, DC bias. Monitor Diode The MD pin on the SY88905 provides low frequency light intensity, laser power out feedback from the monitor diode in the laser diode package. This feedback is used to adjust the IBIAS level through the Automatic Power Control circuit to maintain a near constant power output from the laser diode.
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Micrel
SY88905
SIMULATION GRAPHS
IBIAS vs IBIAS SET
3.5E-02
3.0E-02
2.5E-02
2.0E-02
IBIAS (A)
1.5E-02
1.0E-02
5.0E-03
0.0E+00 0.E+00 1.E-04 2.E-04 3.E-04 4.E-04 5.E-04 6.E-04 7.E-04 8.E-04 IBIAS SET (A)
Figure 1. IBIAS v. IBIAS SET
IBIAS vs RBIAS SET
3.00E-02
2.50E-02
2.00E-02
IBIAS (A)
1.50E-02
1.00E-02
5.00E-03
0.00E+00 1.00E+03
1.00E+04 RBIAS SET (Ohm)
1.00E+05
Figure 2. IBIAS v. RBIAS SET
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Micrel
SY88905
SIMULATION GRAPHS
IPIN vs IPINSET
6.E-04
5.E-04
4.E-04
IPIN (A)
3.E-04
2.E-04
1.E-04
0.E+00 0.E+00
1.E-04
2.E-04
3.E-04 IPIN SET (A)
4.E-04
5.E-04
6.E-04
Figure 3. IPIN v. IPIN SET
IPIN SET vs RIPIN SET
7.00E-04
6.00E-04
5.00E-04
IPIN SET (A)
4.00E-04
3.00E-04
2.00E-04
1.00E-04
0.00E+00 1.00E+03
1.00E+04 RIPIN SET (A)
1.00E+05
Figure 4. IPIN SET v. RPIN SET
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Micrel
SY88905
SIMULATION GRAPHS
V IPIN SET vs IPIN SET
2 1.8 1.6 1.4 1.2 1 0.8 0.6 0.4 0.2 0 0.00E+00
V IPIN SET (V)
1.00E-04
2.00E-04
3.00E-04 IPIN SET (A)
4.00E-04
5.00E-04
6.00E-04
Figure 5. V IPIN SET v. IPIN SET
Typical Vbiasset Voltage Tracking
1.1
Vref - Vbiasset (V)
1.05
1
0.95
0.9 0 40 Junction Temperature (deg C) 80 120
Figure 6. Typical VBIAS SET Voltage Tracking
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Micrel
SY88905
SIMULATION GRAPHS
Typical VPIN SET Voltage Tracking
1.25
VREF - VBIAS SET (V)
1.20
1.15
1.10
1.05 0C
40C
80C
120C
Junction Temperature (deg C)
Figure 7. Typical VPIN SET Voltage Tracking
IBIAS FB vs IMD - IPIN SET (IPIN SET =100 uA)
0.0006
0.0004
0.0002
IBIAS FB (A)
0
-0.0002
-0.0004
-0.0006 -1.50E-04 -1.00E-04 -5.00E-05 0.00E+00 5.00E-05 1.00E-04 1.50E-04
IMD - IPIN SET (A)
Figure 8. IBIAS FB VS. IMD - IPIN SET
PRODUCT ORDERING CODE
Ordering Code SY88905KC SY88905KCTR Package Type K10-1 K10-1 Operating Range Commercial Commercial 7
SY88905
VCC VCC VCC OUT
+TX_DAT -TX_DATA
VEE
REXT
Laser Module
Gigabit EthernetTerminal
DIN DIN
SY88902
RSET VREF EN
OUT RSER
IBIAS SET
VREF VCC IBIAS MD
APPLICATION EXAMPLE FOR 3-CHIP SET SOLUTION
IBIAS SET VBIAS SET
IBIAS FB
SY88905
LOSOUT
PECL
LOSIN VREF EN LOS DOUT DIN VREF IPIN SET VPIN SET GND
RX_LOS
+RX_DAT -RX_DAT
DOUT
SY88903
DIN VBB VLVL VCC VEE VCC
Micrel
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Micrel
SY88905
10 LEAD MSOP (K10-1)
Rev. 00
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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