______________________________________________________________________________________ 11

Single-Port, 40W, IEEE 802.3af/802.3at PSE

Controller with Integrated MOSFET

Pin Description

Pin Configuration

26

27

25

24

10

9

11

12

1

2

OUTP

4

5

6

7

20

21

19

17

16 15

OUT

OUT

I.C.

I.C.

I.C.

MAX5971A

3

18

28

8

N.C.

I.C.

N.C.

23

13 LEGACY

DET

22

14 EN

*EXPOSED PAD, CONNECT TO AGND.

*EP

N.C.

THIN QFN

TOP VIEW

+

PIN

NAME

FUNCTION

1, 2, 3

Analog Low-Side Supply Input. Bypass with an external 100V, 47FF capacitor in parallel with a

4

ILIM1

supply. Use ILIM1 with ILIM2 to enable Class 5 operation and to adjust the Class 5 current-limit

value. See the Electrical Characteristics table and Table 3 in the Class 5 PD Classification section

for details.

5

ILIM2

supply. Use ILIM2 with ILIM1 to enable Class 5 operation and to adjust the Class 5 current-limit

value. See the Electrical Characteristics table and Table 3 in the Class 5 PD Classification section

for details.

6

PWMEN

ply. Leave unconnected to enable the internal PWM to drive the LED pin. Force low to disable the

internal PWM.

7

MIDSPAN

to the digital supply. Leave unconnected to activate the detection collision avoidance circuitry

for midspan PSE systems. Force low to disable this function for an end-point PSE system. The

MIDSPAN logic level latches after the device is powered up or after a reset condition.

8–11, 15

I.C.

12