PM8805 datasheet(9/48 Pages) STMICROELECTRONICS

9 / 48 page

DS12813 Rev 2

9/48

PM8805

Pin description and connection diagram

CLS2

Classification resistor pin for first and second Class Events.

Connect a 0805 classification programming resistor from this pin to

AGND.

The external resistor is activated with a 3.3ms typ. delay with

respect to the classification event.

AGND

This pin is the ground connection for the PM8805 controller.

It must be connected to the other GNDxx pins with short and strong

trace.

7T0

PSE type identification signal.

T0 open drain signal assertion happens as described in Table 3.

This pin is an active low signal, and can be pulled up to VB with an

external resistor.

8T1

PSE type identification signal.

T1 open drain signal assertion happens as described in Table 3.

This pin is an active low signal, and can be pulled up to VB with an

external resistor.

9T2

PSE type identification signal.

T2 open drain signal assertion happens as described in Table 3.

This pin is an active low signal, and can be pulled up to VB with an

external resistor.

FAUX

This pin can be used to allow the PD to be powered with an auxiliary

power source like an external wall adapter connected before the hot

swap MOSFET, with voltage lower than the nominal PoE voltage

range. Pulling up this pin forces the hot swap MOSFET to turn on

when VIN is below the internal UVLO threshold. It may also be used

to implement a UVLO override for a low-voltage PoE application.

It may be used in combination with RAUX and STBY pins to perform

operational modes as described in Table 4.

Use a resistor voltage divider from the auxiliary voltage to AGND to

connect this 5V voltage rating pin: typical value for the threshold is

1.25V.

Connect this pin to AGND if not used.

RAUX

This pin can be used to give high priority to an auxiliary power

source like an external wall adapter connected after the hot swap

MOSFET, without stopping the DC/DC operations.

It may be used in combination with FAUX and STBY pins to perform

operational modes as described in Table 4.

Use a resistor voltage divider from the auxiliary voltage to AGND to

connect this 5V voltage rating pin: typical value for the threshold is

1.25V.

Connect this pin to AGND if not used.

12, 15, 16

IN12

Input for the signals connected to "Tx and Rx" pairs. This signal,

along with IN36 signals, is used to feed the 1st internal bridge.

Table 2. Pin description (continued)

Pin#

Name

Function

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