Datasheet

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AM Discovery
TPS2384
SLUS634D – NOVEMBER 2004 – REVISED MARCH 2007
AUTO MODE FUNCTIONAL DESCRIPTION (continued)
The TPS2384 uses a four-point measurment technique using two low level probe signals (typically 4.4 V and 8.8
V) during the discovery process to determine whether a valid PD is present. The use of a multipoint detection
method for the PD resistor measurement allows accurate detection even when series steering diodes are
present. The low level probe voltages also prevent damage to non-802.3 devices. When a valid PD has been
detected the TPS2384 moves to classification. If a valid PD has not been detected the TPS2384 continues to
cycle through the discovery process. The waveform in Figure 2 shows typical N-pin waveforms for the discovery
of a valid PD and the failure to discovery due to a discovery resistor of 15 k Ω and 33 k Ω .
Figure 2.
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