PM8801 datasheet(25/37 Pages) STMICROELECTRONICS

Part #	PM8801

Description	High-efficiency, IEEE 802.3at compliant, integrated PoE-PD interface and PWM controller

PDF	37 Pages

Scroll/Zoom	100%

Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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25 / 37 page

DocID018560 Rev 2

25/37

PM8801

PD interface

To minimize current consumption during sleep mode, the MPS current is obtained by:

–

the 12 mA driving LED current when the LED is on

–

an internal 12 mA sink when the LED is off

This behavior ensures a 12 mA constant MPS current shape when the MPS is on.

During MPS dropout the consumption is due only to the quiescent current and the average

LED driving current.

IMPDO= Iddq + D*ILED

Figure 11. LED enabled at startup

Ch1: LED, Ch2: ENDC, Ch3: Iinput, Ch4: 5Vout

LED signal will be present also in the case an auxiliary source is used in place of PoE.

If both PoE and auxiliary source are connected, the PoE interface is not providing power to

the DC/DC section, but still provides current to the LED.

When working from an auxiliary source, if the system requires disconnection from the PSE,

it is suggested to turn off the LED for at least 400 msec after insertion of the auxiliary power

jack.

PM8801 Datasheet(PDF) 25 Page - STMicroelectronics