About the at detection of LTC4265

Question

First of all, the customer's configuration uses a bt standard compliant module for PSE and LTC4265 for PD side. 
 In this case, the power can be supplied, but the AT detection flag (T2PSE pin) of the LTC4265 is reset on the third pulse, so the PSE recognizes it as AT, but the PD controller does not show the AT flag. 
 Is this a possible behavior of the LTC4265? Also, if I want to avoid this problem, is there any other way except for bt standard compatible ones?

EHorsma · Accepted Answer

Hello, 
 The third classification event should not reset the AT Flag or change T2PSE behavior. Does the Classification waveform look like Figure 18 or Figure 21?

Figure 21 is sometimes known as a Class Probe. A power limited IEEE 802.3bt PSE may use three events to determine how much power the PD is requesting, then reset the PD. Finally, the PSE provides a single event to signal to the PD it did not receive higher power. 
 Best Regards, 
 Eric

Electronic Design Services - PartnerZone

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About the at detection of LTC4265

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