PM8801 datasheet(11/37 Pages) STMICROELECTRONICS

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DocID018560 Rev 2

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PM8801

Pin descriptions and connection diagram

7GAT1

Main gate driver output of the PWM controller.

DC-DC converter gate driver output with 1A peak sink-source current capability. (5

Ω typ MOSFETs).

8VC

Output of the internal high-voltage regulator.

When the auxiliary transformer winding (if used) raises the voltage on this pin above

the 8 V typ. regulation set point, the internal regulator will shut down, reducing the

internal power dissipation. Filter this pin with a 1 µF typ connected to ground.

9GAT2

Secondary gate driver output.

AUX gate driver output for active clamp or synchronous rectification designs. 1 A

peak sink-source current capability (5

Ω typ MOSFETs).

ARTN

Analog PWM supply ground.

RTN for sensitive analog circuitry including the SMPS current limit amplifier.

RTN2

Power ground for the secondary gate driver.

This pin is also connected to the drain of the internal current-limiting power

MOSFET which closes VSS to the return path of the DC-DC converter.

This pin must be connected to RTN1 and ARTN.

VSS

System low potential input.

Diode "OR'd" to the RJ45 connector and PSE's –48 V supply, it is the more negative

input potential.

VDD

System high potential input.

The diode "OR" of several lines entering the PD, it is the most positive input

potential.

VDD

System high potential input.

The diode "OR" of several lines entering the PD, it is the most positive input

potential.

DET

Detection resistor.

Connect the signature resistance between DET pin and VDD. Current will flow

through the resistor only during the detection phase.

This pin is 100 V rated with negligible resistance with respect to the external 24.9

Ω.

Not Connected.

CLS

Classification resistor.

Connect the classification programming resistor from this pin to VSS.

DIM

LED dimming set.

A resistor between this pin and VSS will set the duty cycle of the PWM current

driving the LED connected to pin 23.

Auxiliary input startup pin.

Pulling up this pin will give high priority to an auxiliary power source like an external

wall adapter. Use a resistor voltage divider from the auxiliary

voltage to ARTN to connect this low voltage rating pin.

Connect this pin to ARTN if not used.

Table 2. Pin descriptions (continued)

Pin#

Name

Function

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