MAX4370ESA+ Maxim Integrated Products, MAX4370ESA+ Datasheet - Page 11

• Manufacturer Part Number: MAX4370ESA+
• Description: IC CNTRLR HOT-SWAP 8-SOIC
• Manufacturer: Maxim Integrated Products
• Type: Hot-Swap Controllerr

Specifications of MAX4370ESA+

• Applications: General Purpose
• Internal Switch(s): No
• Voltage - Supply: 2.7 V ~ 13.2 V
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Select the external N-channel MOSFET according to
the application’s current level. The MOSFET’s R
should be chosen low enough to have a minimum volt -
age drop at full load to limit the MOSFET power dissipa-
tion. High R
has pulsing loads, or it can trigger an external under-
voltage reset monitor at full load. Determine the
device’s power rating requirement to accommodate a
short-circuit condition on the board during start-up (see
MOSFET Thermal Considerations ).
MOSFETs can typically withstand single-shot pulses
with higher dissipation than the specified package rat-
ing. Also, since part of the inrush current limiting is
achieved by limiting the gate dV/dt, it is not necessary
to use a MOSFET with low gate capacitance. Table 2
lists some recommended manufacturers and compo -
nents.
The slow comparator threshold voltage is set at 50mV.
Select a sense resistor that causes a 50mV voltage
drop at a current level above the maximum normal
operating current. Typically, set the overload current at
1.2 to 1.5 times the nominal load current. The fast com-
parator threshold is set at 200mV. This sets the fault
current limit at four times the overload current limit.
Choose the sense-resistor power rating to accommo -
date the overload current (Table 3):
The start-up period (t
tor connected at CTIM. This determines the maximum
time allowed to completely turn on the MOSFET.
The default value for t
floating and is approximately 5.5 µs. This is also the
minimum value (not controlled and dependent on stray
Table 2. Component Manufacturers
__________Applications Information
Sense Resistors
MOSFETs
Current-Regulating Hot-Swap Controller with
COMPONENT
P
DS(ON)
SENSE
______________________________________________________________________________________
= (I
can cause output ripple if the board
START
Start-Up Timing Capacitor (C
START
OVERLOAD
) is determined by the capaci-
Component Selection
is chosen by leaving CTIM
DualSpeed/BiLevel Fault Protection
Dale-Vishay
IRC
Fairchild
International Rectifier
Motorola
)
2
N-Channel MOSFET
MANUFACTURER
· R
SENSE
Sense Resistor
DS(ON)
TIM
)
capacitance). Longer timings are determined by the
value of the capacitor, according to Figure 6, and can
be determined as follows:
Set the t
enhanced and the load capacitor to be completely
charged.
There are two methods of completing the start-up
sequences. Case A describes a start-up sequence that
does not use the current-limiting feature and slowly turns
on the MOSFET by limiting the gate dV/dt. Case B uses
the current-limiting feature and turns on the MOSFET as
fast as possible while still preventing high inrush current.
Figure 6. Start-Up Period vs. C
Table 3. Current Levels vs. R
R
(mΩ)
SENSE
100
10
50
402-564-3131
704-264-8861
888-522-5372
310-322-3331
602-244-3576
PHONE
0.001
1000
0.01
START
100
0.1
10
SLOW COMPARATOR
1
THRESHOLD SET BY
0.01
t
START
OVERLOAD
timer to allow the MOSFET to be
0.1
(ms) = 0.31 · C
(A)
0.5
5
1
CAPACITANCE (nF)
1
TIM
10
www.irctt.co
www.fairchildsemi.com
www.irf.com
www.mot-sps.com/ppd/
www.vishay.com
THRESHOLD SET BY
FAST COMPARATOR
TIM
FAULT CURRENT
INTERNET
100
SENSE
(nF)
1000
(A)
20
4
2
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