Revision Information
This document contains information that is subject to change without notice. Contact Technical
Publications for latest revision information.
CX02068
3.3 Volt Laser Driver IC for 155/622 Mbps
The CX02068 is a highly integrated, programmable laser driver intended for Telecom applications up to 622 Mbps.
Using differential PECL data, the CX02068 supplies the bias and modulation current for driving an edge-emitting
laser. The modulation output can be DC-coupled to the laser diode, giving a significant power saving over ACcoupled operation.
The CX02068 includes automatic power control (APC) to maintain a constant average laser output power over
temperature and life. In addition, the modulation current is temperature compensated to minimize variation in
extinction ratio over temperature. Output flags indicate laser end of life as well as failure of the APC circuitry to
maintain average output power.
Features
Applications
•
•
•
•
•
•
•
•
•
•
•
•
•
Rise and fall times <180 ps
Operates with +3.3 volt supply
DC or AC-coupled modulation drive.
Independently programmable laser bias (to 100 mA) and
modulation currents (to 85 mA).
Automatic laser power control, with programmable temperature
compensation and ‘Slow-Start’.
Bias and modulation current monitors
Failure monitor
Available in BCC+24 , TQFP32 and DIE packages
Available in RoHS compliant packages
OC-3/STM1, SONET/SDH
OC-12/STM4, SONET/SDH
ATM
FTTH
Functional Block Diagram
V DD
OUTOUT+
RD
R SHUNT
C SHUNT
DIN
DIN
GNDA
X100
DIS
ENA
BIAS MON
X1
55
MOD MON
IBIAS
X55
I BIAS
PD
IMOD PP
Failure
Detect
55
FAIL
R MPCSET
OCA SET
OCA
R OCA
R TCSTART
R MODSET
02068-DSH-001-C
R TCSLOPE
V REF
C MPC
V DD
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Ordering Information
Part Number
Package
CX02068B24
BCC+24L
CX02068TQ32
TQFP32
CX02068G-09-T*
BCC+24L, RoHS
CX02068G-TQ32*
TQFP32, RoHS
CX02068DIEWP
Waffle pack
CX02068WAFER
Whole 8” wafer on a 10” grip ring
CX02068EVM
Evaluation board with a CX02068B24
* The letter “G” designator after the part number indicates that the device is RoHS-compliant. Refer to www.mindspeed.com for additional
information.
Revision History
Revision
Level
Date
ASIC Revision
Description
C
Preliminary
April 2006
x
Added RoHS package information, updated format, no specification
changes.
B
Preliminary
May 2005
x
Updated to new data sheet format.
A
Advance
October 2003
x
Advance.
23
22
21
20
DIS
2
18
BIASMON
3
17
OCA SET
MODSET
TCSTART
V
25
MPC
C
26
CC
NC
27
SLOPE
GND
TC
28
OCA
29
V
31
CC
19
32
VCC
DIN
DIN
SET
24
V CC
D
IN
1
24
PD
2
23
GND
D IN
3
22
GND
V CC
4
21
V CC
OUT-
7
18
V CC
N/C
8
17
BIAS
4mm
02068-DSH-001-C
CC
V
PD
A
MOD
13
12
MON
11
BIAS
10
GNDA
9
OUT-
8
OUT+
7
VCC
GND
A
16
V CC
15
CMPC
GND
14
14
6
OCA
OUT+
OCA
13
19
12
6
FAIL
20
N/C
MON
5
GND
11
N/C
FAIL
9
TCSLOPE
15
2068
10
16
5
DIS
4
5mm
ENA
MODMON
BIAS
4mm
1
VCC
GND
ENA
MOD SET
TQFP32 Top View
30
BCC+24L Top View
5mm
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1.0 Product Specification
1.1
Absolute Maximum Ratings
These are the absolute maximum ratings at or beyond which the IC can be expected to fail or be damaged.
Functional operation at these levels is not implied.
Table 1-1.
Absolute Maximum Ratings
Parameter
Rating
Units
Power supply (VCC-GND)
-0.5 to +6.0
V
Operating ambient
-40 to +85
°C
Storage temperature
-65 to +150
°C
Maximum bias current
120
mA
Maximum laser modulation current
(through OUT+/OUT2+, OUT-/OUT2-)
100
mA
1.2
Table 1-2.
Recommended Operating Conditions
Recommended Operating Conditions
Parameter
Rating
Units
Power supply (VCC-GND)
3.3 ± 10%
V
Junction temperature (die)
-40 to +120
°C
Operating ambient
-40 to +85
°C
02068-DSH-001-C
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Product Specification
1.3
DC Characteristics
VCC=+3.3V ± 10%, TA=-40 °C to +85 °C, unless otherwise noted.
Table 1-3.
DC Characteristics
Parameter
Conditions
Min
Typ
Max
Units
Supply current
Excluding IBIAS and IMOD, but with IBIAS
and IMOD set to 50 mA
-
42
47
mA
Bias current adjust range
Limited by IREF across temperature
range
4
-
100
mA
Bias current with output disabled
Tx_Dis = HIGH
-
-
10
µA
Bias current limit adjustment region
TA = +85 °C
20
-
100
mA
100
-
130
µA/°C
Monitor diode reverse bias voltage
2
-
-
V
Monitor diode current adjustment range
10
-
1000
µA
TTL/CMOS input HIGH voltage (enable,
disable)
2.0
-
-
V
TTL/CMOS input LOW voltage (enable,
disable)
-
-
0.8
V
CMOS output HIGH voltage (FAIL, OCA)
2.4
-
-
V
CMOS output LOW voltage (FAIL, OCA)
-
-
0.4
V
2.5
-
-
kΩ
VCC-1.7
-
VCC - VIN (Diff)
4
V
VCC-1.7
-
VCC-0.47
V
Change in bias current limit over
temperature
Differential input impedance
Data and clock inputs
Common-mode input voltage
Self-biased common mode input voltage
02068-DSH-001-C
Data and clock inputs
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Product Specification
1.4
AC Characteristics
VCC = +3.3V ±10%, TA = -40 °C to +85 °C, unless otherwise noted.
Table 1-4.
AC Characteristics
Parameter
Conditions
Differential input voltage
=2 x (DIN+HIGH-DIN+LOW)
(clock inputs follow same relationship)
Modulation current range
Modulation current with output disabled
DIS-HIGH
Min.
Typ.
Max.
Units.
300
-
1860
mV
5
-
85
mA
-
-
300
µA
4
ppm/°C
Programmable range for modulation
current temperature coefficient
Adjustable
500
-
10
Programmable temperature at which
modulation current TC compensation
enables
Programmed by choice of RTCSLOPE
20
-
60
°C
Modulation output rise/fall times
20% to 80% into 25Ω, with matching network
-
-
180
ps
-10
-
+10
%
-
-
1
120
ps
-
-
140
ps
Overshoot of modulation output current
Modulation output pulse width distortion
Modulation output deterministic jitter
Into 25Ω load, with matching network
1
Measured using alternating 1-0 pattern
23
peak-to-peak. Measured into 25Ω load using: 2 -1
PRBS at 622 Mbps includes pulse width distortion
NOTE:
1.
Contact your Mindspeed sales representative concerning availability of parts with a maximum modulation output pulse width distortion of 80 ps
or less
02068-DSH-001-C
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2.0 Pin Description
2.1
Pin Descriptions
Table 2-1.
Pin Descriptions
Pin No
BCC+24
Pin No
TQFP32
Name
-
18
VCC
-
22
GNDA
-
32
VCC
Power supply. Connect to VCC, do not leave open.
-
5, 6, 8, 27
NC
Not connected
-
7
VCC
Power supply. Connect to VCC, do not leave open.
-
25
VCC
Power supply. Connect to VCC, do not leave open.
1
9
ENA
Bias and modulation output enable (TTL/CMOS). HIGH for normal operation
2
10
DIS
Bias and modulation output disable (TTL/CMOS). LOW for normal operation
3
11
BIASMON
Bias monitor. Connect a resistor between this pin and VCC to monitor. Connect to VCCif not in use.
4
12
MODMON
Modulation monitor. Connect a resistor between this pin and VCC to monitor. Connect to VCC if not in
use.
5
13
FAIL
Mean power control failure indicator (TTL/CMOS). Goes low when control loop is no longer able to
maintain constant current at PD
6
14
OCA
Over-Current Alarm (TTL/CMOS). Goes low when IBIAS exceeds the preset bias current limit
7
-
GND
Ground. Connect to VCC, do not leave open.
8
17
BIAS
Laser bias current output
9
1
VCC
Power supply. Connect to VCC, do not leave open.
10
19
OUT+
Positive modulation current output. Sinks current when DIN is HIGH.
11
20
OUT-
Negative modulation current output. Sinks current when DIN is HIGH.
12
23
GNDA
Ground to output stage.(inductor to ground to optimize output stage performance)
13
24
PD
14
26
CMPC
Mean power control dominant pole capacitor
15
15
GND
Ground. Connect to VCC, do not leave open.
16
28
TCSLOPE
02068-DSH-001-C
Function
Power supply. Connect to VCC, do not leave open.
Ground to output stage.(inductor to ground to optimize output stage performance)
Monitor photodiode input. This input is connected to the monitor photodiode anode for automatic
power control.
Connecting a resistor between this pin and ground sets the temperature coefficient of IMODSET (using
the internal IC temperature).
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Pin Description
Table 2-1.
Pin Descriptions (Continued)
Pin No
BCC+24
Pin No
TQFP32
Name
17
-
TCSTART
Secondary temperature coefficient of IMOD. A resistor on this pin to ground sets the threshold
temperature at which the temperature compensation starts.
18
30
MODSET
Modulation current set. Connect a resistor between this pin and ground
19
31
OCASET
Over current alarm set. Connect a resistor between this pin and ground
20
4
VCC
Power supply. Connect to VCC, do not leave open.
21
2
DIN
Positive Data Input (PECL). Self biased.
22
3
DIN
Negative Data Input (PECL). Self biased
23
16
VCC
Power supply. Connect to VCC, do not leave open.
24
29
GND
Ground. Connect to VCC, do not leave open.
02068-DSH-001-C
Function
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3.0 Functional Description
3.1
Overview
The CX02068 laser driver consists of a high-speed modulation driver and a laser bias generator with mean power
control (MPC). It is optimized for high speed, low power operation at 3.3 V supply.
Figure 3-1.
CX02068 Block Diagram
V DD
OUTOUT+
RD
R SHUNT
C SHUNT
DIN
DIN
GNDA
X100
DIS
ENA
BIAS MON
X1
55
MOD MON
IBIAS
X55
I BIAS
PD
IMOD PP
Failure
Detect
55
FAIL
R MPCSET
02068-DSH-001-C
OCA SET
OCA
R OCA
R TCSTART
R TCSLOPE
R MODSET
V REF
C MPC
V DD
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Functional Description
3.2
Features
•
Rise and fall times <180 ps
•
Operates with +3.3 volt supply
•
DC or AC-coupled modulation drive
•
Independently programmable laser bias (to 100 mA) and modulation currents (to 85 mA)
•
Automatic laser power control, with programmable temperature compensation and ‘Slow-Start’
•
Bias and modulation current monitors
•
Failure monitor
•
Available in BCC+24 , TQFP32 and DIE packages
•
Available in RoHS compliant packages
3.3
Modulator
The modulator output stage is designed to drive up to
coupled performance depends on the laser used.
85 mA in either AC-coupled or DC-coupled mode. DC-
The CX02068 modulation output is optimized for driving a 25Ω dynamic load; the minimum required voltage at
OUT+ and OUT- is 0.6 V. To interface with the laser diode, a matching resistor (RD) is required for impedance
matching. An RC shunt network is necessary to compensate for the laser diode parasitic inductance, thereby
improving the optical eye. Typical values are RSHUNT = 51Ω, CSHUNT = 3.3 pF
Any capacitive loading at the cathode of a laser diode will degrade the optical output performance. An inductor is
used to isolate the BIAS pin from the laser cathode.
Figure 3-2.
Typical modulation current vs RMODSET(3.3V)
0.1
0.09
0.08
IMOD (A)
0.07
0.06
0.05
0.04
0.03
0.02
0.01
0
0
5000
10000
15000
20000
25000
30000
35000
RMODSET (Ω )
02068-DSH-001-C
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Functional Description
3.4
Mean Power Control Loop
To maintain constant average optical power, the CX02068 incorporates a control loop to compensate for the
changes in laser threshold current over temperature and lifetime. A monitor photodiode mounted in the laser
package is used to convert the optical power into a photocurrent. The MPC loop adjusts the laser bias current so
that the monitor current is matched to a reference current set by a single external resistor (RMPCSET). The time
constant of the loop is then determined by CMPC.
Figure 3-3.
Typical bias current vs RBIASSET (3.3V)
120
Bias current (mA)
100
80
60
40
20
0
0
10000
20000
30000
40000
RBIASSET (Ω )
Safety logic is provided in order to limit the maximum bias current. The bias current at which the safety logic trips
is set by an external resistor to ground (ROCA) from the OCASET pin. When the bias current limit is reached alarm
flag OCA is asserted LOW. A loop failure alarm is also provided to detect when the bias current can no longer be
adjusted to achieve the desired average optical power.
Figure 3-4.
Typical limiting current vs ROCA (at 25 °C)
100
90
80
IOCA (mA)
70
60
50
40
30
20
10
0
0
10000
20000
30000
40000
ROCA (Ω )
02068-DSH-001-C
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Functional Description
Figure 3-5.
Temperature coefficient of IOCA at different ROCA settings
Change in I OCA over temperature (mA/°C)
0.14
0.12
0.1
0.08
0.06
0.04
0.02
0
0
5000
10000 15000 20000 25000 30000 35000
ROCA (Ω)
Figure 3-6.
02068-DSH-001-C
Typical Eye Diagram
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Functional Description
3.5
Enable Control
The CX02068 incorporates a dual polarity laser driver enable function. When ENA is LOW or DIS is HIGH, both
the bias and modulation currents are off.
3.6
Current Monitors
The CX02068 features bias and modulation current monitor outputs. The BIASMON output sinks a current equal to
nominally 1/55 of the laser bias current (IBIAS). The MODMON output sinks a current equal to nominally 1/55 of the
laser modulation current (IMOD). BIASMON and MODMON should be connected through a pull-up resistor to VCC.
Choose a pull-up resistor value that ensures a voltage at BIASMON greater than VCC -1.6 V and a voltage at
MODMON greater than VCC -1.0 V. These pins should be tied to VCC if not used.
3.7
Slow-Start
For laser safety and reliability, the CX02068 incorporates a slow-start circuit that provides a delay of approximately
200 ns before enabling the laser diode.
3.8
Temperature Compensation
The CX02068 features built in temperature compensation of the modulation current set using external resistors.
Current pulled from TCSLOPE adjusts the slope of the temperature compensation where as current pulled from
TCSTART sets the threshold temperature for the coefficient.
02068-DSH-001-C
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Functional Description
Figure 3-7.
Temperature Compensation Graphs
80mA
0.047
0.045
∆1
IMOD (A)
0.043
TCSLOP
∆2
E
0.041
0.039
0.037
0.035
-40
-20
0
20
40
60
80
100
Temperature (°C)
-40°C
+80°C
TCSTART
0mA
5000
10000
20000
32000
RTCSLOPE - Figures shown are in Ω
RTCSTART = 0Ω, VCC = 3.3V
0.065
0.08
0.075
0.06
0.07
0.065
IMOD (A)
IMOD (A)
0.055
0.05
0.045
0.06
0.055
0.05
0.04
0.045
0.04
0.035
-40
-20
0
20
40
60
80
Temperature (°C)
5000
10000
100
0.035
-40
20000
-20
32000
5000
RTCSLOPE - Figures shown are in Ω
RTCSTART = 250Ω, VCC = 3.3V
02068-DSH-001-C
0
20
40
60
80
100
Temperature (°C)
10000
20000
32000
RTCSLOPE - Figures shown are in Ω
RTCSTART = 400Ω, VCC = 3.3V
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4.0 Packaging Specification
GND
VCC
DIN
DIN
VCC
VCC
Bare Die Information
GND
VCC
Figure 4-1.
Packaging Specification
GND
4.1
1
9
10
VCC
41
ENA
OCASET
DIS
MODSET
GND
GND
BIASMON
MPCSET
MODMON
TCSTART
FAIL
GND
GND
TCSLOPE
OCA
GND
GND
VCC
CMPC
32
31
VCC
PD
GNDA
GNDA
VCCA
OUTN
OUTN
OUTP
OUTP
VCCA
GNDA
BIAS
21
20
Dimensions:
Pad opening 84 x 84 µm
Die size 1790 x 1718 µm
Die thickness 300 µm ± 10%
02068-DSH-001-C
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Packaging Specification
Table 4-1.
Pad Centers
PIN
X
Y
PIN
X
Y
PIN
X
Y
PIN
X
Y
ENA
-727
440
BIAS
-550
-711
VCC
727
-550
GND
550
711
DIS
-727
330
GNDA
-440
-711
CMPC
727
-440
VCC
440
711
GND
-727
220
VCCA
-330
-711
GND
727
-33-
DIN
330
711
BIASMON
-727
110
*OUTP
-210
-711
TCSLOPE
727
-220
DIN
220
711
MODMON
-727
0
*OUTP
-210
-711
GND
727
-110
VCC
110
711
FAIL
-727
-110
*OUTN
100
-711
TCSTART
727
0
GND
0
711
GND
-727
-220
*OUTN
100
-711
MPCSET
727
110
VCC
-110
711
OCA
-727
-330
VCCA
220
-711
GND
727
220
VCC
-440
711
GND
-727
-440
GNDA
330
-711
MODSET
727
330
GND
-550
711
VCC
-727
-550
GNDA
440
-711
OCASET
727
440
PD
550
-711
VCC
727
550
02068-DSH-001-C
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Packaging Specification
Figure 4-2.
TQFP32 Package Information
N
F1
1
PIN 1 ID. 0 0.50P.05
Exposed Pad
E
E1
C0.50P.05X45D
/
-A-
-B-
F2
-D-
D1
Chamfer .203 (4X)
D
TOP VIEW
BOTTOM VIEW
DETAIL X
DETAIL A
A2
A
b
SIDE VIEW
Table 4-2.
Package Dimensions
Dimensions
Tolerance
5 x 5 x 1.0 mm TQFP, +2.00 mm FP
N
Lead count
32
A
Max.
1.20
A2
±0.05
1.00
D
±0.15
7.00
D1
±0.05
5.00
E
±0.15
7.00
E1
±0.05
5.00
F1
±0.10
2.67
F2
±0.10
2.67
02068-DSH-001-C
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Packaging Specification
Figure 4-3.
BCC+24L Package Information
TOP VIEW
(PIN 1 CO RNER)
BOTTOM VIEW
3.15
0.50 ± 0.10
0.50 ± 0.10
2.20
0.50 TYP.
Y
Figure 4-4.
"A"(PIN 1 CO RNER)
0.15
C.L(PKG .)
C.L(PKG .)
2.20
3.15
4.00 ± 0.10
0.50 TYP.
3.20
4.00 ± 0.10
X
"B"
3.20
"C"
SMT Mounting Guides
0.025
mm
0.35m m
P C B land
0.2mm
0.025
mm
Pad
1.3mm
0.3m m
0.025
mm
1.0mm
0.1mm
0.4
mm
B C C P ad s view ed fro m ab o ve
0.2m m
S older R esist
M ask
P aste S tencil
1.0m m
Pad
0.025m m
PC B land
Lower R ight Pad
0.55mm
0.125m
m
0.025mm
1.0mm
0.025m
m
0.45m m
0.125m
m
0.025m m
0.025m
m
0.45mm
C o rn er P ad s
0.55m m
Solder R esis t
M as k
P aste S tencil
E xp o sed Cen tral Pad (co n n ected to g ro u n d p lan e)
1.26m m
2.1m m
Pad
0.1m m
P C B land
1.26mm
0.025mm
0.025mm
0.1mm
0.1mm
2.1mm
0.1m m
0.025m m
Paste Stencil
Solder R esist
M ask
0.025mm
0.025m m
0.675m m
0.675m m
W indow
S tencil
02068-DSH-001-C
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General Information:
Telephone: (949) 579-3000
Headquarters - Newport Beach
4000 MacArthur Blvd., East Tower
Newport Beach, CA 92660
© 2006 Mindspeed Technologies®, Inc. All rights reserved.
Information in this document is provided in connection with Mindspeed Technologies® ("Mindspeed®") products.
These materials are provided by Mindspeed as a service to its customers and may be used for informational
purposes only. Except as provided in Mindspeed’s Terms and Conditions of Sale for such products or in any
separate agreement related to this document, Mindspeed assumes no liability whatsoever. Mindspeed assumes
no responsibility for errors or omissions in these materials. Mindspeed may make changes to specifications and
product descriptions at any time, without notice. Mindspeed makes no commitment to update the information and
shall have no responsibility whatsoever for conflicts or incompatibilities arising from future changes to its
specifications and product descriptions. No license, express or implied, by estoppel or otherwise, to any
intellectual property rights is granted by this document.
THESE MATERIALS ARE PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND, EITHER EXPRESS OR
IMPLIED, RELATING TO SALE AND/OR USE OF MINDSPEED PRODUCTS INCLUDING LIABILITY OR
WARRANTIES RELATING TO FITNESS FOR A PARTICULAR PURPOSE, CONSEQUENTIAL OR INCIDENTAL
DAMAGES, MERCHANTABILITY, OR INFRINGEMENT OF ANY PATENT, COPYRIGHT OR OTHER
INTELLECTUAL PROPERTY RIGHT. MINDSPEED FURTHER DOES NOT WARRANT THE ACCURACY OR
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MATERIALS. MINDSPEED SHALL NOT BE LIABLE FOR ANY SPECIAL, INDIRECT, INCIDENTAL, OR
CONSEQUENTIAL DAMAGES, INCLUDING WITHOUT LIMITATION, LOST REVENUES OR LOST PROFITS,
WHICH MAY RESULT FROM THE USE OF THESE MATERIALS.
Mindspeed products are not intended for use in medical, lifesaving or life sustaining applications. Mindspeed
customers using or selling Mindspeed products for use in such applications do so at their own risk and agree to
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