VSC7984
Datasheet
−1.20
−1.30
−1.40
−1.50
VTEMP (V)
−1.60
−1.70
−1.80
−1.00
−2.00
−2.10
−40 −30 −20 −10
0
10 20 30 40 50 60 70 80 90 100 110 120
Junction Temperature ( ˚C)
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Figure 2. VTEMP vs. Junction Temperature
Power Consumption
The VSC7984 consumes 300 mA typical from a –5.2 V supply and 315 mA maximum with a 2.5 V output swing.
The following equations provide the typical current consumption for a given modulation and offset setting:
P
D
= 5.5 V × I
EE
= 5.5 V × [165 mA + (V
OM
/25) + 35 mA] for V
OM
<1.4 V
(EQ 1)
P
D
= 5.5 V × I
EE
= 5.5 V × [165 mA + (V
OM
/25) + (–0.024 × (V
OM
) + 0.07)] for V
OM
>1.4 V
(EQ 2)
V
CC
Output Bias Voltage (V
BIAS
)
Output HIGH Voltage (V
OH
)
Output Compliance Voltage (V
OC
)
Output Modulation Voltage (V
OM
)
Output LOW Voltage (V
OL
)
Figure 3. Output Voltage Range Specifications
Modulation, Bias, and Data Eye Crossing Point
Internal feedback stabilizes the VSC7984 modulation and offset voltages so no external operational amplifiers are
required to stabilize modulation and bias currents. For optimal stability, it is recommended that a reference voltage
relative to the most negative rail be used to set the VMOD and VOFS control voltages. The graphs in
point range versus their control voltage.
4 of 16
VMDS-10029 Revision 4.1
January 19, 2007
VITESSE [ VITESSE SEMICONDUCTOR CORPORATION ]
