PM8805 datasheet(32/48 Pages) STMICROELECTRONICS

No de pièce	PM8805

Description	IEEE 802.3bt PoE-PD interface with embedded dual active bridge

PDF	48 Pages

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Fabricant	STMICROELECTRONICS [STMicroelectronics]

Site Internet	http://www.st.com

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32 / 48 page

PM8805 overview

PM8805

32/48

DS12813 Rev 2

Figure 9. Simplified rear aux connections

4.11

Operation modes and STBY, FAUX, RAUX command signals

In the PM8805, 3 command signals are available which may be combined to obtain 7

different operation modes, as synthetically described in Table 10. The table describes the

behavior of the PGD signal, the hot swap MOSFET, the charge pump, the active bridge and

the MPS circuitry depending on the configuration on the inputs.

In order to set a "1" signal on the inputs, it is needed to drive the voltage of those pins above

their threshold (1.25 V typ.). Below that threshold the configuration cannot be detected, and

the system behaves as if it has a "0" input, which is the default PoE standard configuration.

Depending on the value of the voltage source used as pull-up for STBY, FAUX, RAUX, the

resistor divider must be sized taking into account the voltage on the command pins above

their thresholds but still below their AMR (6 V).

PM8805 Fiches technique(PDF) 32 Page - STMicroelectronics