1
SY88905
Micrel, Inc.
M9999-081005
hbwhelp@micrel.com or (408) 955-1690
DESCRIPTION
■DC bias current adjustable to 25mA
■Buffered Loss-of-Signal output when used with
SY88903
■Monitor Diode power control circuit
■Designed for use with SY88902 and SY88903
■Single power supply
■Available in 10-pin (3mm) MSOP
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.
FEATURES
LASER DIODE CONTROLLER
WITH APC SY88905
APPLICATIONS
■Controller for High Speed Optical Data Transmission
■1.25Gbps Gigabit Ethernet
■531 Mbps and 1062Mbps Fibre Channel
■622Mbps SONET
■Gigabit Interface Converter
BLOCK DIAGRAM
IPIN SET
VCC
IBIAS FB
IBIAS MD
VREF 2
-
+
IBIAS SET
VREF
GND
40X
VREF2
LOSIN
LOSOUT
Rev.: C Amendment: /0
Issue Date: August 2005
2
SY88905
Micrel, Inc.
M9999-081005
hbwhelp@micrel.com or (408) 955-1690
PIN NAMES
Pin Type Description
VCC Power Positive Power supply
GND Power Ground
LOSIN TTL Input Loss-of-Signal Input from SY88903
VREF Analog Output Reference Voltage
IPIN SET Analog Input Adjustable, Resistor to VREF sets Monitor Diode Photo Current Reference
LOSOUT PECL Output Loss-of-Signal PECL output
IBIASFB Analog Output Monitor Diode Feedback
IBIASSET Analog Input Adjustable, Resistor to VREF sets the DC bias current for the Laser Diode
MD Analog Input Monitor Diode Connection
IBIAS Analog Input DC bias current for the Laser Diode
PACKAGE/ORDERING INFORMATION
10-Pin MSOP (K10-1)
Ordering Information
Package Operating Package Lead
Part Number Type Range Marking Finish
SY88905KC K10-1 Commercial 905 Sn-Pb
SY88905KCTR(1) K10-1 Commercial 905 Sn-Pb
SY88905KH K10-1 Commercial 905 with Pb-Free
Pb-Free bar-line indicator NiPdAu
SY88905KHTR(1) K10-1 Commercial 905 with Pb-Free
Pb-Free bar-line indicator NiPdAu
Note:
1. Tape and Reel.
1LOS
IN
LOS
OUT
GND
I
BIAS
V
CC
10 V
REF
I
BIAS SET
I
BIAS FB
I
PIN SET
MD
9
8
7
6
2
3
4
5
MSOP
K10-1
3
SY88905
Micrel, Inc.
M9999-081005
hbwhelp@micrel.com or (408) 955-1690
LOGIC DIAGRAM
Symbol Rating Value Unit
VCC Power Supply Voltage 0 to +7.0 V
LOSIN Input Voltage 0 to VCC V
LOSOUT, IPIN SET Others; I/O Voltage –0.3, VCC +0.3 V
IBIASFB, IBIAS SET
TAOperating Temperature Range 0 to +85 ˚C
Tstore Storage Temperature Range –55 to +125 ˚C
IPIN SET, IBIAS SET, IMD Max. Sink Current 1 mA
IBIASFB Max. Source Current 1 mA
IBIAS Max. Sink Current 30 mA
IVREF Max. Source Current 2 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.
ABSOLUTE MAXIMUM RATINGS(1)
TA = 0°CTA = +25°CTA = +85°C
Symbol Parameter Min. Max. Min. Max. Min. Max. Unit Condition
VOH Output HIGH Voltage
V
CC
– 1025 V
CC
– 880 V
CC
– 1025 V
CC
– 880 V
CC
– 1025 V
CC
– 880
mV 50Ω to VCC–2V
VOL Output LOW Voltage
V
CC
–1810 V
CC
–1620 V
CC
–1810 V
CC
–1620 V
CC
–1810 V
CC
–1620
mV 50Ω to VCC–2V
100H ECL DC ELECTRICAL(1)
VCC = +5V ±10%
Note:
1. 100H circuits are designed to meet the DC specifications shown in the table where transverse airflow greater than 500lfpm is maintained.
4
SY88905
Micrel, Inc.
M9999-081005
hbwhelp@micrel.com or (408) 955-1690
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.
TA = 0°CTA = +25°CTA = +85°C
Symbol Parameter Min. Typ. Max. Min. Typ. Max. Min. Typ. Max. Unit Conditions
ICC Power Supply Current — — 40 — 28 40 — — 40 mA No output load
IBIAS SET IBIAS SET Input Current — — 0.9 — — 0.9 — — 0.9 mA
IBIAS IBIAS Output Current 0.5 — 25 0.5 — 25 0.5 — 25 mA
ABIAS IBIAS Current Gain 28 — 44 28 37 44 28 — 44 =IBIAS / IBIAS SET
VREF Reference Voltage 2.30 — 3.30 2.30 2.75 3.30 2.30 — 3.30 V IREF = -100µA
∆VPIN SET VPIN SET Voltage Tracking 0.95 — 1.35 0.95 1.13 1.35 0.95 — 1.35 V =VREF – VPIN SET
∆VBIAS SET VBIAS Voltage Tracking 0.8 — 1.20 0.8 1.0 1.20 0.8 — 1.20 V =VREF – VBIAS SET
VCOMP BIAS Compliance Voltage 0.1 — 1.0 0.1 0.4 1.0 0.1 — 1.0 V IBIAS = 15mA
IBIAS FB Feedback Current(1) 350 — — 350 500 — 350 — — µA
ABIAS FB Feedback Gain(2) 4 — 14 4 — 14 4 — 14
DC ELECTRICAL CHARACTERISTICS
VCC = +5V ±10%
Notes:
1. |IMD – IPIN SET| = 100µA
2. |IBIAS FB| / |IMD – IPIN SET|
Note:
1. Individual product specifications over-ride general specifications.
TTL DC ELECTRICAL CHARACTERISTICS
VCC = +5V ±10%
TA = 0°CTA = +25°CTA = +85°C
Symbol Parameter Min. Max. Min. Max. Min. Max. Unit Condition
VIH Input HIGH Voltage 2.0 — 2.0 — 2.0 — V —
VIL Input LOW Voltage — 0.8 — 0.8 — 0.8 V —
IIH Input HIGH Current — 20 — 20 — 20 µAVIN = 2.7V
— 100 — 100 — 100 VIN = VCC
IIL Input LOW Current — –0.3 — –0.3 — –0.3 mA VIN = 0.5V
VIK Input Clamp Voltage — –1.2 — –1.2 — –1.2 V IIN = –12mA
5
SY88905
Micrel, Inc.
M9999-081005
hbwhelp@micrel.com or (408) 955-1690
SIMULATION GRAPHS
Figure 1. IBIAS v. IBIAS SET
Figure 2. IBIAS v. RBIAS SET
IBIAS vs IBIAS SET
0.0E+00
5.0E-03
1.0E-02
1.5E-02
2.0E-02
2.5E-02
3.0E-02
3.5E-02
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
I
BIAS SET
(A)
I
BIAS
(A)
I
BIAS
vs R
BIAS SET
0.00E+00
5.00E-03
1.00E-02
1.50E-02
2.00E-02
2.50E-02
3.00E-02
1.00E+03 1.00E+04 1.00E+05
R
BIAS SET
(Ohm)
I
BIAS
(A)
6
SY88905
Micrel, Inc.
M9999-081005
hbwhelp@micrel.com or (408) 955-1690
SIMULATION GRAPHS
Figure 3. IPIN v. IPIN SET
Figure 4. IPIN SET v. RPIN SET
I
PIN SET
vs R
IPIN SET
0.00E+00
1.00E-04
2.00E-04
3.00E-04
4.00E-04
5.00E-04
6.00E-04
7.00E-04
1.00E+03 1.00E+04 1.00E+05
R
IPIN SET
(A)
I
PIN SET
(A)
IPIN vs IPINSET
0.E+00
1.E-04
2.E-04
3.E-04
4.E-04
5.E-04
6.E-04
0.E+00 1.E-04 2.E-04 3.E-04 4.E-04 5.E-04 6.E-04
IPIN SET (A)
IPIN (A)
7
SY88905
Micrel, Inc.
M9999-081005
hbwhelp@micrel.com or (408) 955-1690
SIMULATION GRAPHS
Figure 5. V IPIN SET v. IPIN SET
Figure 6. Typical VBIAS SET Voltage Tracking
V IPIN SET vs IPIN SET
0
0.2
0.4
0.6
0.8
1
1.2
1.4
1.6
1.8
2
0.00E+00 1.00E-04 2.00E-04 3.00E-04 4.00E-04 5.00E-04 6.00E-04
IPIN SET (A)
V
IPIN SET
(V)
Typical Vbiasset Voltage Tracking
0.9
0.95
1
1.05
1.1
04080120
Junction Temperature (deg C)
Vref - Vbiasset (V)
8
SY88905
Micrel, Inc.
M9999-081005
hbwhelp@micrel.com or (408) 955-1690
SIMULATION GRAPHS
Figure 7. Typical VPIN SET Voltage Tracking
Figure 8. IBIAS FB VS. IMD - IPIN SET
Typical VPIN SET Voltage Tracking
1.05
1.10
1.15
1.20
1.25
0C 40C 80C 120C
Junction Temperature (deg C)
V
REF
- V
BIAS SET
(V)
IBIAS FB vs IMD - IPIN SET (IPIN SET =100 uA)
-0.0006
-0.0004
-0.0002
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)
IBIAS FB (A)
9
SY88905
Micrel, Inc.
M9999-081005
hbwhelp@micrel.com or (408) 955-1690
APPLICATION EXAMPLE FOR 3-CHIP SET SOLUTION
OUT
V
CC
V
EE
SY88905
D
IN
D
IN
LOSOUT
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
10
SY88905
Micrel, Inc.
M9999-081005
hbwhelp@micrel.com or (408) 955-1690
10 LEAD MSOP (K10-1)
Rev. 00
MICREL, INC. 2180 FORTUNE DRIVE SAN JOSE, CA 95131 USA
TEL + 1 (408) 944-0800 FAX + 1 (408) 474-1000 WEB http://www.micrel.com
The information furnished by Micrel in this data sheet is believed to be accurate and reliable. However, no responsibility is assumed by Micrel for its use.
Micrel reserves the right to change circuitry and specifications at any time without notification to the customer.
Micrel Products are not designed or authorized for use as components in life support appliances, devices or systems where malfunction of a product can
reasonably be expected to result in personal injury. Life support devices or systems are devices or systems that (a) are intended for surgical implant into
the body or (b) support or sustain life, and whose failure to perform can be reasonably expected to result in a significant injury to the user. A Purchaser’s
use or sale of Micrel Products for use in life support appliances, devices or systems is at Purchaser’s own risk and Purchaser agrees to fully indemnify
Micrel for any damages resulting from such use or sale.
© 2005 Micrel, Incorporated.
