MICREL SY88905KC

LASER DIODE
CONTROLLER
WITH APC
FEATURES
SY88905
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.
PIN CONFIGURATION
LOSIN 1
10 VREF
LOSOUT 2
APPLICATIONS
9 IBIAS SET
MSOP
K10-1
GND 3
8 IBIAS FB
IBIAS 4
7
IPIN SET
VCC 5
6
MD
■
■
■
■
■
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
IBIAS
MD
VREF2
LOSIN
40X
+
VREF 2
VCC
GND
VREF
IBIAS SET
IBIAS FB
IPIN
SET
Rev.: B
1
Amendment: /1
Issue Date: July 2000
SY88905
Micrel
PIN DEFINITIONS
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
ABSOLUTE
MAXIMUM RATINGS(1)
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
IBIASFB, IBIAS SET
Others; I/O Voltage
–0.3, VCC +0.3
V
TA
Operating 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.
100H ECL DC ELECTRICAL(1)
VCC = +5V ±10%
TA = 0°C
Symbol
Parameter
Min.
Max.
TA = +25°C
Min.
Max.
TA = +85°C
Min.
Max.
Unit
Condition
VOH
Output HIGH Voltage
VCC – 1025 VCC – 880 VCC – 1025 VCC – 880 VCC – 1025 VCC – 880
mV
50Ω to VCC–2V
VOL
Output LOW Voltage
VCC –1810 VCC –1620 VCC –1810 VCC –1620 VCC –1810 VCC–1620
mV
50Ω to VCC–2V
NOTE:
1. 100H circuits are designed to meet the DC specifications shown in the table where transverse airflow greater than 500lfpm is maintained.
2
SY88905
Micrel
DC ELECTRICAL CHARACTERISTICS
VCC = +5V ±10%
TA = 0°C
Symbol
TA = +85°C
Min.
Typ.
Max.
Min.
Typ.
Max.
ICC
Power Supply Current
—
—
40
—
28
40
—
—
40
mA
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
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
Feedback
Current(1)
350
—
—
350
500
—
350
—
—
µA
Feedback
Gain(2)
4
—
14
4
—
14
4
—
14
IBIAS FB
ABIAS FB
Parameter
TA = +25°C
Min. Typ. Max. Unit
Conditions
No output load
=IBIAS / IBIAS SET
NOTE:
1. |IMD – IPIN SET| = 100µA
2. |IBIAS FB| / |IMD – IPIN SET|
TTL DC ELECTRICAL CHARACTERISTICS
VCC = +5V ±10%
TA = 0°C
Symbol
Parameter
TA = +25°C
TA = +85°C
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
100
—
—
20
100
—
—
20
100
µA
VIN = 2.7V
VIN = VCC
IIL
Input LOW Current
—
–0.3
—
–0.3
—
–0.3
mA
VIK
Input Clamp Voltage
—
–1.2
—
–1.2
—
–1.2
V
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.
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.
Laser Diode Supply Current
The SY88905 provides the adjustable drive current for
the laser diode, DC bias.
3
SY88905
Micrel
SIMULATION GRAPHS
IBIAS vs IBIAS SET
3.5E-02
3.0E-02
2.5E-02
IBIAS (A)
2.0E-02
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
IBIAS (A)
2.00E-02
1.50E-02
1.00E-02
5.00E-03
0.00E+00
1.00E+03
1.00E+04
RBIAS SET (Ohm)
Figure 2. IBIAS v. RBIAS SET
4
1.00E+05
SY88905
Micrel
SIMULATION GRAPHS
IPIN vs IPINSET
6.E-04
5.E-04
3.E-04
2.E-04
1.E-04
0.E+00
0.E+00
1.E-04
2.E-04
3.E-04
4.E-04
5.E-04
IPIN SET (A)
Figure 3. IPIN v. IPIN SET
IPIN SET vs RIPIN SET
7.00E-04
6.00E-04
5.00E-04
IPIN SET (A)
IPIN (A)
4.E-04
4.00E-04
3.00E-04
2.00E-04
1.00E-04
0.00E+00
1.00E+03
1.00E+04
RIPIN SET (A)
Figure 4. IPIN SET v. RPIN SET
5
1.00E+05
6.E-04
SY88905
Micrel
SIMULATION GRAPHS
V IPIN SET vs IPIN SET
2
1.8
1.6
V IPIN SET (V)
1.4
1.2
1
0.8
0.6
0.4
0.2
0
0.00E+00
1.00E-04
2.00E-04
3.00E-04
4.00E-04
5.00E-04
6.00E-04
IPIN SET (A)
Figure 5. V IPIN SET v. IPIN SET
Typical Vbiasset Voltage Tracking
Vref - Vbiasset (V)
1.1
1.05
1
0.95
0.9
0
40
80
Junction Temperature (deg C)
Figure 6. Typical VBIAS SET Voltage Tracking
6
120
SY88905
Micrel
SIMULATION GRAPHS
Typical VPIN SET Voltage Tracking
VREF - VBIAS SET (V)
1.25
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
IBIAS FB (A)
0.0002
0
-0.0002
-0.0004
-0.0006
-1.50E-04
-1.00E-04
-5.00E-05
0.00E+00
5.00E-05
IMD - IPIN SET (A)
Figure 8. IBIAS FB VS. IMD - IPIN SET
PRODUCT ORDERING CODE
Ordering
Code
Package
Type
Operating
Range
SY88905KC
K10-1
Commercial
SY88905KCTR
K10-1
Commercial
7
1.00E-04
1.50E-04
SY88905
Micrel
APPLICATION EXAMPLE FOR 3-CHIP SET SOLUTION
Gigabit EthernetTerminal
+TX_DAT
–TX_DATA
RX_LOS
+RX_DAT
–RX_DAT
LOSOUT
EN
DOUT
DOUT
DIN
DIN
PECL
VCC
VEE
VCC
REXT
OUT
VREF
DIN
DIN
VBB
VLVL
OUT RSER
IBIAS
VCC
VCC
MD
IPIN SET
VPIN SET
VREF
SY88905
RSET VREF
SY88902
EN
LOSIN
LOS
SY88903
VCC VEE
Laser
Module
VCC
GND
IBIAS SET
VBIAS SET
IBIAS FB
IBIAS SET
VREF
8
SY88905
Micrel
10 LEAD MSOP (K10-1)
Rev. 00
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
9