max5938 Maxim Integrated Products, Inc., max5938 Datasheet - Page 21

• Manufacturer Part Number: max5938
• Description: Max5938 -48v Hot-swap Controller With Vin Step Immunity, No Rsense, And Overvoltage Protection
• Manufacturer: Maxim Integrated Products, Inc.

Power-Up-to-Fault-Management Fault:
1) Same as step 1 above. [GATE turn-on]
2) Same as step 2 above. [V
3) GATE ramps to 90% of full enhancement while
A step GATE cycle occurs only after a successful
power-up GATE cycle to full enhancement occurs and
as a result of a positive V
relative to V
Step-to-Full-Enhancement Fault:
1) A V
2) After a step is detected, V
3) Following the 350µs of GATE pulldown, GATE is
4) When GATE reaches the gate threshold voltage of
5) When V
-48V Hot-Swap Controller with V
V
GATE is rapidly pulled to V
ment is initiated. [Fault management]
above STEP
detection]
response to the step. When V
GATE is immediately pulled to V
off the power MOSFET. GATE is held at V
350µs to damp any ringing. Once GATE is pulled to
V
safely drop below STEP
plete a step GATE cycle to full enhancement without
initiating fault management. [GATE pulldown]
allowed to float for 650µs. At this point, the GATE
begins to ramp with 52µA charging the gate of the
power MOSFET. [GATE turn-on]
the power MOSFET, V
toward the new lower V
GATE is below the MOSFET threshold, the MOSFET
is off and V
time constant of the load. [V
rapidly to full enhancement and the step GATE
cycle is complete. If STEP_MON remains above
STEP
enhancement and V
GATE remains at 90% and is not pulled to full
enhancement. In this condition, if V
74% of V
STEP
and the step GATE cycle is complete. PGOOD
remains asserted throughout the step GATE cycle.
[Full enhancement]
OUT
EE
, the gate cycle has begun and STEP_MON can
IN
TH
TH
remains above 74% V
step occurs resulting in STEP_MON rising
, GATE is rapidly pulled to full enhancement
EE
OUT
when GATE has ramped to 90% of full
).
CB
TH
OUT
ramps below 74% V
______________________________________________________________________________________
before STEP_MON drops below
before V
will droop depending on the RC
OUT
No R
GATE Cycle During V
OUT
OUT
remains above 74% of V
TH
IN
OUT
EE
OUT
OUT
. In the interval where
step (all voltages are
and successfully com-
rises above V
begins to ramp down
CB
EE
OUT
ramp]
, at which point the
SENSE
and fault manage-
rises above V
ramp]
CB
EE
rises above V
OUT
, the GATE pulls
, rapidly turning
drops below
SC
IN
. [Step
EE
, and Overvoltage Protection
SC
Step
CB
SC
for
in
,
,
Step-to-Fault-Management Fault:
1) Same as step 1 above. [Step detection]
2) Same as step 2 above. [GATE pulldown]
3) Same as step 3 above. [GATE turn-on]
4) Same as step 4 above. [V
5) If STEP_MON is below STEP
It should be emphasized that while STEP_MON remains
above STEP
blocked. During this time it is possible for there to be
multiple events involving V
falling below 74% V
V
where GATE is first pulled low then allowed to ramp up.
Then finally, when V
fully enhanced.
An OV GATE cycle occurs only after a successful
power-up GATE cycle to full enhancement and as a
result of a momentary excursion of OV above the OV
threshold voltage. An OV GATE cycle does not result in
an OV fault unless OV remains above the threshold for
more than 1.5ms (all voltages are relative to V
OV GATE Cycle to Full enhancement:
1) When OV rises above the OV threshold voltage,
2) Following the GATE pulldown, GATE is allowed to
OUT
GATE is immediately pulled to V
off the power MOSFET. GATE is held at V
nitely while OV is above the OV threshold voltage. It
is held for an additional 350µs to damp any ringing.
[GATE pulldown]
float for 650µs. At this point, the GATE begins to
ramp with 52µA charging the gate of the power
MOSFET. [GATE turn-on]
to 90% of full enhancement and V
above 74% V
Fault management is initiated and PGOOD is de-
asserted. If STEP_MON is above STEP
GATE ramps to 90% of full enhancement and V
remains above 74% of V
It is not pulled to full enhancement nor is it pulled to
V
V
GATE is rapidly pulled to full enhancement and a
fault is avoided. Conversely, if STEP_MON drops
below STEP
V
deasserted. [Fault management]
EE
EE
CB
rises above V
. In this condition, if V
, fault management is initiated, and PGOOD is
GATE Cycle During Momentary Overvoltage
before STEP_MON drops below STEP
TH
IN
TH
the current fault management is
CB,
first, the GATE is rapidly pulled to
CB
Step Immunity,
SC
OUT
GATE is rapidly pulled to V
. In each of these events, when
, a full GATE cycle is initiated
conditions are met, it will be
OUT
CB
OUT
OUT
, GATE remains at 90%.
rising above V
TH
ramp]
drops below 74% of
when GATE ramps
EE
, rapidly turning
OUT
EE
EE
TH
remains
SC
).
indefi-
when
then
OUT
TH
EE
21
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