The sense resistor (RSNS) must be
placed close to the TPS1211x-Q1 and then connect RSNS using the
Kelvin techniques. Refer to Choosing the Right Sense Resistor Layout for
more information on the Kelvin techniques.
For all the applications, TI recommends a 0.1 μF
or higher value ceramic decoupling capacitor between VS terminal and GND.
Consider adding RC network at the supply pin (VS) of the controller to improve
decoupling against the power line disturbances.
The high-current path from the board input to the
load, and the return path, must be parallel and close to each other to minimize
loop inductance.
The external MOSFETs must be placed close to the
controller such that the GATE of the MOSFETs are close to PU/PD pins to form
short GATE loop. Consider adding a place holder for a resistor in series with
the Gate of each external MOSFET to damp high frequency oscillations if need
arises.
Place a TVS diode at the input to clamp the
voltage transients during hot-plug and fast turn-off events.
The external boot-strap capacitor must be placed
close to BST and SRC pins to form very short loop.
The ground connections for the various components
around the TPS1211x-Q1 must be connected directly to each other, and to the
TPS1211x-Q1 GND, and then connected to the system ground at one point. Do not
connect the various component grounds to each other through the high current
ground line.
The DIODE pin sources current to measure the
temperature. TI recommends BJT MMBT3904 to use as
a remote temperature sense element. Take care in
the PCB layout to keep the parasitic resistance
between the DIODE pin and the MMBT3904 low so as
not to degrade the measurement. In addition, TI
recommends to make a Kelvin connection from the
emitter of the MMBT3904 to the GND of the part to
ensure an accurate measurement. Additionally, a
small 1000 pF bypass capacitor must be placed in
parallel with the MMBT3904 to reduce the effects
of noise.