MAX5935CAX Maxim Integrated Products, MAX5935CAX Datasheet - Page 16

• Manufacturer Part Number: MAX5935CAX
• Description: Hot Swap & Power Distribution
• Manufacturer: Maxim Integrated Products

Specifications of MAX5935CAX

• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Quad Network Power Controller
for Power-Over-LAN
Figure 3. PGOOD Timing
16
Figure 2. Detection, Classification, and Power-Up Port
Sequence
OUT_
PGOOD
-18V
-48V
-4V
-9V
______________________________________________________________________________________
POK
0V
0V
80ms
150ms
t
DETI
t
PGOOD
150ms
t
DETII
21.3ms
t
CLASS
t
A sense resistor (R
V
stances, the voltage across R
threshold V
internal current-limiting circuit regulates the GATE volt-
age, limiting the current to I
transient conditions, if the SENSE_ voltage exceeds
V
quickly recover from the current overshoot. During
startup, if the current-limit condition persists, when the
startup timer, t
the STRT_FLT_ bit is set. In the normal powered state,
the MAX5935 checks for overcurrent conditions as
determined by V
t
overcurrent period. The t
V
pace when V
decrement for the t
repeated short-duration overcurrents. When the counter
reaches the t
port and asserts the IMAX_FLT_ bit. For a continuous
overstress, a fault latches exactly after a period of
t
t
After power-off due to an overcurrent fault, and if the
RSTR_EN bit is set, the t
reset but starts decrementing at the same slower pace.
The MAX5935 allows the port to be powered on only
when the t
automatic duty-cycle protection to the external MOSFET
to avoid overheating. The duty cycle is programmable
using R16h[6-7].
The MAX5935 continuously flags when the current
exceeds the maximum current allowed for the class as
indicated in the CLASS status register. When class
overcurrent occurs, the MAX5935 sets the IVC bit in
register R09h.
During startup and normal operation, an internal circuit
senses the voltage at OUT_ and reduces the current-
limit value when (V
function helps to reduce the power dissipation on the
FET. The current limit eventually reduces to 1/3 of I
when (V
FAULT
FAULT
FAULT
SENSE
EE
SU_LIM
, monitors the load current. Under all circum-
. V
is programmable using R16h[2-3] and R28[4-7].
counter sets the maximum-allowed continuous
OUT
, a fast pulldown circuit activates in order to
exceeds V
SU_LIM
FAULT
_ - V
SU_LIM
FAULT
SENSE
START
EE
, is programmable using R27h[4-7].
counter is at zero. This feature sets an
FLT_LIM
S
FLT_LIM
. If SENSE_ exceeds V
) > 50V (see Figure 4).
FAULT
), connected between SENSE_ and
OUT
limit, the MAX5935 powers off the
, times out, the port shuts off and
drops below V
_ - V
FAULT
FAULT
Overcurrent Protection
counter allows for detecting
and decreases at a slower
= ~88% of V
LIM
EE
counter increases when
timer is not immediately
) > 30V. The foldback
= V
S
Foldback Current
never exceeds the
SU_LIM
FLT_LIM
SU_LIM
/ R
SU_LIM
. A slower
S
. During
. The
, an
LIM