82573 Datasheet, PDF (24/39 Pages) Intel Corporation – GbE Controllers

82573—Datasheet
Table 10.
PNP Specification (Sheet 2 of 2)
Symbol
Description
Power
Dissipation
Maximum Total Power Dissipation
h_FE
DC Current Gain
f_T
Current Gain Product Bandwidth
Min
-
100
10
Max
1.35
-
-
Units
W
-
MHz
3.3.4.7
Internal LVR Board Schematic
When using the internal voltage regulator controllers built into the 82573, resistors
might need to be placed in series with the emitter in order to prevent the PNP
transistors from overheating. These series resistors dissipate a portion of the power
that would otherwise be dissipated by the PNP devices. The value and power rating of
the resistors must be carefully chosen to balance thermal limits against the PNP
characteristics against total current draw. The regulator must never drop below the
minimum V_ce and out of the linear region.
The effective resistance of the pass resistors should equal approximately 1 Ω and have
a combined power dissipation rating of 0.5 Watts for the 82573. Figure 4 shows the
recommended implementation.
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