Datasheet

MAX5922
+48V, Single-Port Network Power Switch
For Power-Over-LAN
14 ______________________________________________________________________________________
OUT
AGND_S
27, 28
7
INTERNAL TO MAX5922
V
PROBE_VOLTAGE
I
MAX
= 1.5mA
D1
R
PD
POWER DEVICE
Figure 3. PSE Detection Source
INCREMENT
OVERCURRENT
COUNTER
N
N
Y
N
Y
N
EN = HIGH?
RESET
POWER-ON
N
Y
N
t
ZCDEL
= 350ms?
Y
Y
Y
N
N
N
N
Y
Y
N
Y
Y
N
Y
N
Y
N
Y
Y
OVERCURRENT
= HIGH
OVERCURRENT
COUNTER = 60?
START POWER-UP
RESET FAULT, ZC
OVERCURRENT
DETECTED
N
Y
RESET
OVERCURRENT
COUNTER
Y
V
OUT
- V
IN
< V
THPOK
?
V
IN
> UVLO
TH
?
EN = LOW?
LATCH = HIGH?
t
RESTART
ELAPSED
SWITCH
SHUT-OFF
FAULT = LOW
THERMAL
SHUTDOWN
DETECTED?
SWITCH
SHUT-OFF
ZC = LOW
RESET t
ZCDEL
INCREMENT
t
ZCDEL
RESET
t
ZC_DEG
IS I
OUT
< I
ZCTH
?
POK HIGH
AFTER t
POK_DLY
LOW TO HIGH
INCREMENT
t
ZC_DEG
t
ZC_DEG
= 10ms?
RESET
t
ZC_DEG
t
ZCDEL
EN LOW
TO HIGH
TRANSACTION
DETECTED?
POK LOW
AFTER t
POK_DLY
HIGH TO LOW
ZC_EN = HIGH?
IS POK HIGH?
Figure 4. Operational Flow Chart (MAX5922B/MAX5922C with DET_DIS Connected High)