List of figures

AN2783

4/47

List of figures

Figure 1.

PM8800 demonstration kit . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Figure 2.

Demonstration kit schematic. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Figure 3.

Assembly view: top and bottom layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

Figure 4.

Top layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 5.

Inner layer 1 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 6.

Inner layer 2 . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

Figure 7.

Bottom layer . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

Figure 8.

Inrush current limit vs. RIRL . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19

Figure 9.

DC current limit vs. RDC. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20

Figure 10.

Output power vs. VAUXII . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22

Figure 11.

5 V out - standard board with diode rectification. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29

Figure 12.

5 V out - high-power board with synchronous rectification . . . . . . . . . . . . . . . . . . . . . . . . . 29

Figure 13.

3.3 V out - standard board with diode rectification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

Figure 14.

3.3 V out - high-power board with synchronous rectification . . . . . . . . . . . . . . . . . . . . . . . 30

Figure 15.

Startup of the PM8800 demonstration kit with 5 V 1 A . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Figure 16.

Startup of the PM8800 demonstration kit with 5 V 4 A . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Figure 17.

Details of the inrush phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Figure 18.

Details of the soft-start phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 31

Figure 19.

VDS and VGS of the primary MOSFET for 5 V 1 A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Figure 20.

VDS and VGS of the primary MOSFET for 5 V 4 A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

Figure 21.

Details of the synchronous rectifier MOSFET voltage with 48 V and 4 A out . . . . . . . . . . 32

Figure 22.

Output voltage ripple at 4 A output current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33

Figure 23.

Output voltage ripple at 4 A output current (1 sec persistence) . . . . . . . . . . . . . . . . . . . . . 33

Figure 24.

Dynamic load 1 A to 4 A: output voltage (up) and output current (down) . . . . . . . . . . . . . 33

Figure 25.

PM8800A response to a 6 A overload condition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Figure 26.

PM8800A recovering from a 6 A overload condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Figure 27.

PM8800A response to a short on the load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Figure 28.

PM8800A recovering from a short on the load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Figure 29.

Internal short on the secondary winding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

Figure 30.

Switch between 48 V PoE and 24 V AUXII with 5 V at 2 A . . . . . . . . . . . . . . . . . . . . . . . . 35

Figure 31.

back to 48 V removing the 24 V AUXII voltage with 5 V at 2 A . . . . . . . . . . . . . . . . . . . . . 35

Figure 32.

Switch between 48 V PoE and 12 V AUXII with 5 V at 2 A . . . . . . . . . . . . . . . . . . . . . . . . 36

Figure 33.

Back to 48 V removing the 12 V AUXII voltage with 5 V at 2 A . . . . . . . . . . . . . . . . . . . . . 36

Figure 34.

Startup of the PM8800 demonstration kit with 3.3 V, 1 A . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Figure 35.

Startup of the PM8800 demonstration kit with 3.3 V, 3 A . . . . . . . . . . . . . . . . . . . . . . . . . . 36

Figure 36.

Details of the inrush phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Figure 37.

Details of the soft-start phase . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Figure 38.

VDS and VGS of the primary MOSFET for 3.3 V 1 A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Figure 39.

VDS and VGS of the primary MOSFET for 3.3 V 3 A . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

Figure 40.

Details of the synchronous rectifier MOSFET voltage with 48 V and 3 A output current . . 38

Figure 41.

Output voltage ripple at 3 A output current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

Figure 42.

Output voltage ripple at 3 A output current (1 sec persistence) . . . . . . . . . . . . . . . . . . . . . 38

Figure 43.

Dynamic load 1 to 3 A: output voltage (up) and output current (down) . . . . . . . . . . . . . . . 39

Figure 44.

PM8800A response to a 5 A overload condition. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Figure 45.

PM8800A recovering from a 5 A overload condition . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

Figure 46.

PM8800A response to a short on the load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Figure 47.

PM8800A recovering from a short on the load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Figure 48.

Internal short on the secondary winding . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40