MAX4272ESA Maxim Integrated Products, MAX4272ESA Datasheet - Page 20

• Manufacturer Part Number: MAX4272ESA
• Description: Hot Swap & Power Distribution
• Manufacturer: Maxim Integrated Products

Specifications of MAX4272ESA

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

3V to 12V Current-Limiting Hot-Swap Controllers
with Autoretry, DualSpeed/BiLevel Fault Protection
Figure 12. Power-On Reset
Figure 13. Power-On Reset and Temperature
The ON and INC comparator inputs and the STAT and
OUTC can be pulled to voltages up to 14V indepen-
dently of V
and not be turned on through the internal protection
diodes. In some applications, it is useful to use connec-
tors with staggered leads. In Figure 14, the ON pin
forces the removable board to be powered up only
when all connections are made.
The auxiliary V
used to sustain the input voltage required for the device
to operate during a short-circuit condition on the board.
When a short occurs, the main system power supply
could collapse and the MAX4273 will not have enough
voltage to keep the gate drive operational and turn off
the external MOSFET. If the fault is not removed, the
system could remain in a sustained short-circuit state.
Connect a 1µF capacitor from the AUXVCC pin to GND.
This capacitor will deliver the necessary energy to the
20
V
IN
______________________________________________________________________________________
V
IN
IN
IN
INC
IN
, thus allowing parts to be daisy-chained
MAX4273
CC
SENSE
is available on the MAX4273 and is
MAX4273
SENSE
GND
LLMON
GATE
OUTC
INC
LLMON
GATE
OUTC
REF
ON
NTC
Auxiliary V
RESET
μP
V
OUT
CC
gate drive until the MOSFET is turned off and the main
supply recovers. The 1µF capacitor is charged from V
through an internal switch during normal operation.
The MAX4271/MAX4272/MAX4273 can be used on the
backplane to regulate current upon insertion of a
removable card (Figure 16). This allows multiple cards
with different input capacitance to be inserted into the
same slot even if the card doesn’t have on-board hot-
swap protection.
The MAX4271/MAX4272/MAX4273 current-limiting fea-
ture is active during the startup period set by CTIM.
The startup period can be triggered if V
to ON through a trace on the card. Once t
expired (timed out), the load capacitance has to be
charged or a fault condition is detected. To ensure
startup with a fixed CTIM, t
the time required to charge the board capacitance. The
maximum load capacitance is calculated as follows:
The voltage at V
inrush and fault conditions. When a short condition
occurs on the board, the fault current can be higher
than the fast comparator current limit. The gate voltage
Figure 14. Fail-Safe Connector
RESET
V
CC
C
BOARD
BACKPLANE
IN
Maximum Load Capacitance
< t
must be above the UVLO during
REMOVABLE
CARD
START
START
✕
I
1M
10k
FAST,SET
ON
IN
has to be longer than
Input Transients
MAX4271
MAX4272
MAX4273
SENSE GATE
IN
/ V
is connected
IN
START
has
IN