Datasheet

Calculate the MOSFET thermal resistance required
for a short to ground.
Z
θJA
= (150°C - 85°C) / (5V
✕
10A) = 1.30°C/W
Using t
START
= 1ms as the pulse duration, use
Figure 17 to select a duty cycle. The duty cycle
should be about 0.01 or less. This implies t
RETRY
=
t
START
/ 0.01 = 100ms. From Figure 8, C
TIM
= 10nF.
Layout Considerations
To take full tracking advantage of the switch response
time to an output fault condition, it is important to keep
all traces as short as possible and to maximize the
high-current trace dimensions to reduce the effect of
undesirable parasitic inductance. Place the MAX4271/
MAX4272/MAX4273 close to the card’s connector. Use
a ground plane to minimize impedance and induc-
tance. Minimize the current-sense resistor trace length
(<10mm), and ensure accurate current sensing with
Kelvin connections (Figure 18).
When the output is short circuited, the voltage drop
across the external MOSFET becomes large. Hence,
the power dissipation across the switch increases, as
does the die temperature. An efficient way to achieve
good power dissipation on a surface-mount package is
to lay out two copper pads directly under the MOSFET
package on both sides of the board. Connect the two
pads to the ground plane through vias, and use
enlarged copper mounting pads on the top side of the
board.
MAX4271/MAX4272/MAX4273
3V to 12V Current-Limiting Hot-Swap Controllers
with Autoretry, DualSpeed/BiLevel Fault Protection
______________________________________________________________________________________ 23
CTIM
CSPDGND
1
2
8
7
ON
STATSENSE
GATE
IN
SO
TOP VIEW
3
4
6
5
MAX4271
MAX4272
Pin Configurations
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
RTH OUTC
INC
REF
ON
STAT
CTIM
CSPD
CTON
MAX4273
QSOP/SO
AUXVCC
IN
CEXT
SENSE
GATE
LLMON
GND
Figure 18. Kelvin Connections for the Current-Sense Resistors
SENSE RESISTOR
HIGH-CURRENT PATH
MAX4271
MAX4272
MAX4273