High current-carrying power-path connections must be as short as possible and
must be sized to carry at least twice the full-load current.
The GND (PowerPAD) pin must be
tied to the PCB ground plane at the terminal of the IC with the shortest
possible trace. The PCB ground must be a copper plane or island on the board. TI
recommends to have a separate ground plane island for the eFuse. This plane does
not carry any high currents and serves as a quiet ground reference for all the
critical analog signals of the eFuse. The device ground plane must be connected
to the system power ground plane using a star connection.
The optimal placement of the
decoupling capacitor (CIN) is closest to the IN and GND pins of the
device. Care must be taken to minimize the loop area formed by the
bypass-capacitor connection, the IN pin, and the GND pin of the IC.
Locate the following support components close to their connection pins:
RILM or RPLM
RIOCP
CDLY
CdVdT
Resistors for OVP
Connect the other end of the
component to the GND pin of the device with shortest trace length. The trace
routing for these components to the device must be as short as possible to
reduce parasitic effects on the current limit, overcurrent blanking interval,
and soft-start timing.
Because the bias current on ILM pin directly controls the overcurrent protection
behavior of the device, the PCB routing of this node must be kept away from any
noisy (switching) signals.
Protection devices such as TVS,
snubbers, capacitors, or diodes must be placed physically close to the device
they are intended to protect. These protection devices must be routed with short
traces to reduce inductance. For example, TI recommends a protection Schottky
diode to address negative transients due to switching of inductive loads. TI
recommends to add a ceramic decoupling capacitor (COUT) of 1 μF or
greater between OUT and GND. These components must be physically close to the
OUT pins. Care must be taken to minimize the loop area formed by the Schottky
diode and bypass-capacitor connection, the OUT pin, and the GND pin of the
IC.