+48V, Single-Port Network Power Switch

For Power-Over-LAN

______________________________________________________________________________________

13

INCREMENT

OVERCURRENT

COUNTER

N

N

Y

RESET

OVERCURRENT

COUNTER

N

POK LOW

HIGH TO LOW

N

Y

N

EN = HIGH?

RESET

POWER-ON

N

Y

N

RESET COUNTERS

START PD DECTECTION

Cl0 = CL1 = CL2 = HIGH

START

PD CLASSIFICATION

CL0 = CL1 = CL2 = HIGH

Y

N

CLASS = H?

Y

START POWER-UP

RESET

FAULT AND ZC

Y

INCREMENT

SWITCH SHUTOFF

FAULT = LOW

Y

LATCH = HIBH

Y

EN = LOW?

Y

Y

N

N

N

SWITCH

SHUT-OFF

ZC = LOW

OVERCURRENT

DETECTED

ZC_EN =

HIGH?

N

Y

INCREMENT

RESET

Y

IS DCA HIGH?

SAMPLE AND HOLD

MEASURE

OUTPUT IN HIGH-Z

N

Y

N

REPORT CLASS

STATUS

THERMAL

SHUTDOWN

DETECTED?

N

Y

IS POK HIGH?

RESET

Y

N

Y

N

ELAPSED?

Y

N

Y

Y

IS

OK?

OVERCURRENT

CONDITION?

OVERCURRENT

COUNTER = 60?

POK HIGH

AFTER

LOW TO HIGH

10ms?

Note 1

FORCE

WAIT 1/2tDET

*FOR THE MAX5922B, THE DCA FUNCTION IS INTERNALLY DISABLED. FOR THE MAX5922C, THE DCA FUNCTION IS INTERNALLY ENABLED.

Figure 2. Operational Flow Chart (MAX5922A and MAX5922B/MAX5922C with DET_DIS Connected Low)