VITESSE
SEMICONDUCTOR CORPORATION
Preliminary Data Sheet
VSC7939
Features
• Power Supply: 3.3V or 5V
±
5%
• AC-Coupled to Laser Diode
SONET/SDH 3.125Gb/s
Laser Diode Driver with Automatic Power Control
Applications
• SONET/SDH at 622Mb/s, 1.244Gb/s,
2.488Gb/s, 3.125Gb/s
• Full-Speed Fibre Channel (1.062Gb/s)
• Programmable Modulation Current: 5mA to 60mA
• Programmable Bias Current: 1mA to 100mA
• Enable /Disable Control
• Typical Rise/Fall Times of 60ps
• Automatic Optical Average Power Control
• Supply Current of 33mA at 3.3V
General Description
The VSC7939 is a single 3.3V or 5V supply laser diode driver specially designed for SONET/SDH applica-
tions up to 3.125Gb/s. External resistors set a wide range of bias and modulation currents for driving the laser.
Data and clock inputs accept differential PECL signals. The automatic power control (APC) loop maintains a
constant average optical power over temperature and lifetime. The dominant pole of the APC loop can be con-
trolled with an external capacitor. Other features include enable/disable control, short-circuit protection for the
modulation and bias inputs, short rise and fall times, programmable slow-start circuit to set laser turn-on delay,
and failure-monitor output to indicate when the APC loop is unable to maintain the average optical power. The
VSC7939 is available in die form or in a 32-pin TQFP package.
Block Diagram
3.3V Operation
L
P
IOUT+
IOUT-
MUX
DATA+
DATA-
CLK+
CLK-
D
SET
V
CC
LATCH
C
D
C
F
R
F
V
CC
Q
CLR
Q
BIAS
V
CC
ENABLE
DISABLE
APC
MD
FAIL
MODSET
BIASMAX
CAPC
APCSET
1nF
V
CC
MODMON
BIASMON
G52350-0, Rev 3.2
02/26/01
©
VITESSE
SEMICONDUCTOR CORPORATION
• 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
L
P
Page 1
VITESSE
SEMICONDUCTOR CORPORATION
SONET/SDH 3.125Gb/s
Laser Diode Driver with Automatic Power Control
Preliminary Data Sheet
VSC7939
Electrical Characteristics
Table 1: AC Specifications
AC specifications are guaranteed by design and characterization. Typical values are for 3.3V.
Symbol
t
SU
t
H
Parameter
Input Latch Setup Time
Input Latch Hold Time
Enable/Start-up Delay
Min
100
100
Typ
Max
Units
ps
ps
Conditions
LATCH=high
LATCH=high
250
60
60
10
80
7
20
80
80
50
ns
ps
ps
ps
bits
ps
p-p
Jitter BW=12kHz to 20MHz,
0-1 pattern.
20% to 80%
20% to 80%
See Notes 1, 2
t
R
t
F
PWD
CID
MAX
t
J
Output Rise Time
Output Fall Time
Pulse Width Distortion
Maximum Consecutive Identical Digits
Jitter Generation
NOTES: (1) Measured with 622Mb/s 0-1 pattern, LATCH=high. (2) PWD = (wider pulse - narrower pulse) / 2).
Table 2: DC Specifications
Symbol
Parameter
Min
Typ
Max
Units
Conditions
R
MODSET
=7.3kΩ
R
BIASMAX
=4.8kΩ
I
BIAS
and I
MOD
excluded
V
CC
=5V
Voltage at BIAS pin=(V
CC
-1.6)
ENABLE=low or
DISABLE=high
(1)
APC open loop. I
BIAS
=100mA
APC open loop. I
BIAS
=1mA
Refers to part-to-part variation
I
CC
I
BIAS
I
BIAS-OFF
S
BIAS
Supply Current
TBD
45
mA
Bias Current Range
Bias Off Current
Bias Current Stability
Bias Current Absolute Accuracy
1
100
100
230
900
±15
mA
µA
ppm/°C
%
V
VR
MD
I
MD
Monitor Diode Reverse Bias Voltage
Monitor Diode Reverse Current Range
Monitor Diode Bias Setpoint Stability
Monitor Diode Bias Absolute Accuracy
1.5
18
-480
-15
5
-50
90
15
60
200
1000
480
µA
ppm/°C
%
mA
µA
ENABLE=low or
DISABLE=high
(1)
I
MD
=1mA
(2)
I
MD
=18µA
(2)
Refers to part-to-part variation
I
MOD
I
MOD-OFF
Modulation Current Range
Modulation Off Current
Page 2
©
VITESSE
SEMICONDUCTOR CORPORATION
• 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
G52350-0, Rev 3.2
02/26/01
VITESSE
SEMICONDUCTOR CORPORATION
Preliminary Data Sheet
VSC7939
Symbol
Parameter
Modulation Current Absolute Accuracy
Modulation Current Stability
A
BIAS
A
MOD
BIASMON to I
BIAS
Gain
MODMON to I
MON
Gain
SONET/SDH 3.125Gb/s
Laser Diode Driver with Automatic Power Control
Min
-480
Typ
±15
-50
250
37
29
Max
480
Units
%
ppm/°C
A/A
A/A
Conditions
See Note 2
I
MOD
=60mA
I
MOD
=5mA
I
BIAS
/I
BIASMON
I
MOD
/I
MODMON
NOTES: (1) Both I
BIAS
and I
MOD
will turn off if any of the current set pins are grounded. (2)
Assumes laser diode to monitor diode transfer func-
tion does not change with temperature.
Table 3: PECL and TTL/CMOS Inputs and Outputs Specifications
Symbol
V
ID
V
ICM
I
IN
V
IH
V
IL
Parameter
Differential Input Voltage
Common-Mode Input Voltage
Clock and Data Input Current
TTL Input High Voltage
(ENABLE, LATCH)
TTL Input Low Voltage
(ENABLE, LATCH)
TTL Output High Voltage (FAIL)
TTL Output Low Voltage (FAIL)
Min
100
V
CC
-
1.49
-1
2.0
Typ
V
CC
-
1.32
Max
1600
V
CC
-
V
ID
/4
10
Units
mV
p-p
V
µA
V
Conditions
(DATA+)-(DATA-)
PECL-compatible
0.8
2.4
0.1
V
CC
-
0.3
V
CC
0.44
V
V
V
Sourcing 50µA
Sinking 100µA
G52350-0, Rev 3.2
02/26/01
©
VITESSE
SEMICONDUCTOR CORPORATION
• 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Page 3
VITESSE
SEMICONDUCTOR CORPORATION
SONET/SDH 3.125Gb/s
Laser Diode Driver with Automatic Power Control
Preliminary Data Sheet
VSC7939
Absolute Maximum Ratings
(1)
Power Supply Voltage (V
CC
)............................................................................................................. -0.5V to +7V
Current into BIAS.....................................................................................................................-20mA to +150mA
Current into OUT+, OUT- ...............................................................................................................................TBD
Current into MD .............................................................................................................................-5mA to +5mA
Current into FAIL ......................................................................................................................... -10mA to 30mA
Voltage at DATA+, DATA-, CLK+, CLK-, ENABLE, LATCH......................................... -0.5V to (V
CC
+ 0.5V)
Voltage at APCFILT, MODSET, BIASMAX, APCSET, MD, FAIL ............................................. -0.5V to +3.0V
Voltage at OUT+, OUT- ..................................................................................................... -0.5V to (V
CC
+ 1.5V)
Voltage at BIAS .................................................................................................................. -0.5V to (V
CC
+ 0.5V)
Continouous Power Dissipation (T
A
= +85°C, TQFP derate 20.8mW/°C above +85°C) .......................1350mW
Operating Junction Temperature Range ...................................................................................... -55°C to +150°C
Storage Temperature Range ........................................................................................................ -65°C to +165°C
NOTE: (1) CAUTION: Stresses listed under “Absolute Maximum Ratings” may be applied to devices one at a time without caus-
ing permanent damage. Functionality at or above the values listed is not implied. Exposure to these values for extended
periods may affect device reliability.
Recommended Operating Conditions
Positive Voltage Rail (V
CC
)..................................................................................................... +3.135V to +5.25V
Negative Voltage Rail (GND) ............................................................................................................................0V
Modulation Current (I
MOD
)
(1)
.......................................................................................................................30mA
Ambient Temperature Range (T
A
)................................................................................................. -40°C to +85°C
NOTE:
(1) V
CC
= 3.3V, I
BIAS
= 60mA.
Page 4
©
VITESSE
SEMICONDUCTOR CORPORATION
• 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
G52350-0, Rev 3.2
02/26/01
VITESSE
SEMICONDUCTOR CORPORATION
Preliminary Data Sheet
VSC7939
Bare Die Pad Descriptions
SONET/SDH 3.125Gb/s
Laser Diode Driver with Automatic Power Control
Figure 1: Pad Assignments
1773µm (0.0698")
Pad 11
VCC1
Pad 12
GND1
Pad 13
LATCH
Pad 14
ENABLE
Pad 10
CLK-
Pad 9
CLK+
Pad 8
VCC1
Pad 7
GND1
Pad 6
VCC1
Pad 5
DATA-
Pad 4
DATA+
Pad 3
VCC1
Pad 2
GND1
Pad 1
GND2
(Pin 7)
(Pin 6)
(Pin 5)
(Pin 4)
(Pin 3)
(Pin 2)
(Pin 1)
(Pin 8)
(Pin 32)
Pad 48
VCC2
Pad 47
BIASMAX
Pad 46
MODSET
Pad 45
GND2
(Pin 9)
(Pin 31)
20µm
(0.0008")
Pad 15
(Pin 10)
DISABLE
Pad 16
GND1
Pad 17
(Pin 11)
BIASMON
Pad 18
(Pin 12)
MODMON
(Pin 30)
(Pin 29)
Pad 44
APCSET
Pad 43
RESERVED
Pad 42
GND3
Pad 41
PB_GND
(Pin 28)
2233µm
(0.0879")
VSC7939
Pad 19
FAIL
Pad 20
GND4
Pad 21
PB_GND
(Pin 13)
(Pin 27)
Pad 40
GND3
Pad 39
PB_GND
Pad 38
CAPC
Pad 37
VCC3
Pad 36
GND3
Pad 22
(Pin 14)
APCFILT
Pad 23
GND4
Pad 24
VCC4
Pad 25
BIAS
(Pin 15)
(Pin 26)
(Pin 16)
(Pin 25)
(Pin 17)
(Pin 18)
Pad 26
PB_GND1
Pad 27
VCC4
Pad 28
DB_OUT+
(Pin 19)
Pad 29
OUT+
(Pin 20)
Pad 30
OUT-
Pad 31
DB_OUT-
(Pin 21)
Pad 32
VCC4
(Pin 22)
Pad 33
GND4
(Pin 23)
Pad 34
GND3
(Pin 24)
Pad 35
MD
1773µm x 2233µm (0.0698" x 0.0879")
625
µm (0.0246
"
)
115
µm (0.0045
"
)
95µm x 95µm (0.0037
"
x 0.0037
"
)
Pad to Pad Clearance:
20µm (0.0008
"
)
Pad Passivation Opening:
95µm x 95µm (0.0037
"
x 0.0037
"
)
Scribe Size:
75µm (0.0030
"
)
Die Size:
Die Thickness:
Pad Pitch:
Pad Size:
75µm
(0.0030")
G52350-0, Rev 3.2
02/26/01
©
VITESSE
SEMICONDUCTOR CORPORATION
• 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
Page 5
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