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95
0 0.5 1 1.5 2 2.5 3 3.5 4 4.5 5 5.5
I -OutputCurrent- A
O
Efficiency-%
J2,(RJ-45)
J3(Flyback)
V =48V
I
RJ-45=48V
0
0.1
0.2
0.3
0.4
0.5
0.6
0 5 10 15 20 25 30
PowertoLoad-W
Current- A
R15Current
R19Current
Setup
Figure 3. Efficiency
To avoid current limiting at the TPS2376-H PD, a current booster circuit composed of Q1, Q2, R15, and
R19 is used to create a secondary return path for the input current. Figure 4 shows the current distribution
between the two paths. Detailed explanation on this circuit is provided in the TI application report,
High-Power PoE Using TPS2375/77-1 (SLVA225 ).
Figure 4. Booster Circuit Current Distribution
SLVU197B – March 2007 – Revised September 2007 TPS2376HEVM 5
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