MAX34561 Datasheet, PDF (10/11 Pages) Maxim Integrated Products – 12V/5V Hot-Plug Switch

12V/5V Hot-Plug Switch
drop across the corresponding power MOSFET and the
load current. See the Thermal Shutdown with Autoretry
Enabled typical operating curves for details.
Applications Information
Exposed Pad
The exposed pad is also a heatsink for the device. The
exposed pad should be connected to a large trace or
plane capable of dissipating heat from the device.
Decoupling Capacitors
It is of utmost importance to properly bypass the device's
supply pins. A decoupling capacitor absorbs the energy
stored in the supply and board parasitic inductance
when the FET is turned off, thereby reducing the magni-
tude of overshoot at VCC. This can be accomplished by
using a high-quality (low ESR, low ESL) ceramic capaci-
tor connected directly between the VCC and GND pins.
Any series resistance with this bypass capacitor lowers
its effectiveness and is not recommended. A minimum
0.5µF ceramic capacitor is required. However, depend-
ing on the parasitic inductances present in the end appli-
cation, a larger capacitor could be necessary.
MAX34561
LOAD
LOAD
LOAD
LOAD
ILIM
TO APPLICATION
R_ILIM
Unused Pins
If only one side (5V or 12V) of the device is being used,
it is required that the unused VCC, AR, CTIMER, and
VRAMP pins be connected to GND. Leaving these input
pins unconnected can result in interference of the proper
operation of the active portion of the device.
LOAD and ILIM Connections
Small parasitic resistances in the bond wires of the LOAD
pins and in the traces connected to the LOAD pins can
result in a voltage offset while current is flowing. Since
the voltage drop across RILIM is used to set the ISCL and
IOVL limits, this induced offset can increase the value of
ISCL and IOVL from the specified values for any given
RILIM. To greatly reduce this offset, it is recommended
that one of the LOAD pins have a dedicated connection
to ILIM though RILIM, and not be used to pass the LOAD
current (Figure 1). This would leave three LOAD pins to
pass ILOAD, which should be sufficient. Because there
is only a small amount of current passed from this lone
LOAD pin to ILIM, there is a negligible voltage offset
applied to the internal comparator. This method is the
best way to attain an accurate current limit for ILOAD.
Package Information
For the latest package outline information and land patterns,
go to www.maxim-ic.com/packages. Note that a “+”, “#”, or
“-” in the package code indicates RoHS status only. Package
drawings may show a different suffix character, but the drawing
pertains to the package regardless of RoHS status.
PACKAGE
TYPE
24 TQFN-EP
PACKAGE
CODE
T2444+4
OUTLINE
NO.
21-0139
LAND
PATTERN NO.
90-0022
Figure 1. LOAD and ILIM Connections
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