VITESSE
SEMICONDUCTOR CORPORATION
Preliminary Data Sheet
VSC7940
Symbol
Parameter
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
-50
250
37
29
Max
480
Units
ppm/°C
Conditions
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 Input
/
Output 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
0.8
Units
mV
p-p
V
mA
V
V
V
V
Conditions
(DATA+)-(DATA-)
PECL-compatible
2.4
0.1
V
CC
-
0.3
V
CC
0.44
Sourcing 50µA
Sinking 100µA
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)
Continuous 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
).............................................................................................................................. +5V
Negative Voltage Rail (GND) ............................................................................................................................ 0V
Ambient Temperature Range (T
A
).................................................................................................. -40°C to +85°C
G52357-0, Rev 3.2
05/11/01
©
VITESSE
SEMICONDUCTOR CORPORATION
• 741 Calle Plano • Camarillo, CA 93012
Tel: (800) VITESSE • FAX: (805) 987-5896 • Email: prodinfo@vitesse.com
Internet: www.vitesse.com
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