PM8801 datasheet(24/37 Pages) STMICROELECTRONICS

Part #	PM8801

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

PDF	37 Pages

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Manufacturer	STMICROELECTRONICS [STMicroelectronics]

Direct Link	http://www.st.com

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24 / 37 page

PD interface

PM8801

24/37

DocID018560 Rev 2

In case of thermal shutdown, MPS is released, making sure that current consumption is

below the threshold and allowing the PSE to detach the PD.

When the PM8801 is powered by an auxiliary source (see Section 6 ), the MPS current is

not activated.

Figure 10. Sleep mode with pulsed MPS current

Ch1: ENSL, Ch2: VSS-RTN. Ch3: Iinput, Ch4: 5Vout

4.7

LED driving

The PM8801 features a current-driven LED output. The LED is enabled when the ENDC pin

is driven high, or automatically enabled in sleep mode.

The LED driver sources a PWM current at 250 Hz frequency and 12 mA typical amplitude.

The LED brightness is adjustable connecting a resistor RDC at 1% accuracy between DIM

and VSS. The correspondence between duty-cycle and resistor values are shown in the

following Table 8.

Table 8. LED duty cycle selection

LED duty cycle D

RD [Ω]

0>1 M

15%

453 k

33%

243 k

47%

162 k

75%

110 k

PM8801 Datasheet(PDF) 24 Page - STMicroelectronics