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PoE Performance Characteristics
22.5 Ripple Current and Voltage
Figure 11
and
Figure 12
show the PoE and AUX input ripple current, respectively, under full load. In both
cases, the input ripple current is attenuated to less than 10 mA pk-pk by the input filter.
Horizontal Resolution: 50 µs/div.
Trace 1: The PoE input current ripples (AC coupled). 20 mAV/div.
Trace 2: The FFT of Trace 1. Horizontal 500 kHz/div. Vertical 5 mA/div
Figure 11. PoE Input Current Ripples under Full Load
Horizontal Resolution: 5 µs/div.
Trace 1: The AUX input current ripples (AC coupled). 10 mA/div.
Trace 2: The FFT of Trace 1 showing the peak value of the harmonics. Horizontal 500 kHz/div. Vertical 2.5 mA/div.
Figure 12. AUX Input Current Ripple Under Full Load
Figure 13
shows the output ripple voltage. The FFT of the output ripple voltage indicates that the ripple
harmonics are below 15 mV pk-pk.
15
SNOA476C – October 2006 – Revised April 2013
AN-1521 POEPHYTEREV-I / -E Evaluation Board
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