Low ESR/ESL capacitors must
be connected close to the device between GVDD and GND and between BSTx and
SHx pins to support high peak currents drawn from GVDD and BSTx pins during
the turn-on of the external MOSFETs.
To prevent large voltage transients at the drain of the top MOSFET, a low
ESR electrolytic capacitor and a good quality ceramic capacitor must be
connected between the high side MOSFET drain and ground.
In order to avoid large negative transients on the switch node (SHx) pin,
the parasitic inductances between the source of the high-side MOSFET and the
source of the low-side MOSFET must be minimized.
In order to avoid unexpected
transients, the parasitic inductance of the GHx, SHx, and GLx connections
must be minimized. Minimize the trace length and number of vias wherever
possible. Minimum 10 mil and typical 15 mil trace width is recommended.
Place the gate driver as close to the MOSFETs as possible. Confine the high
peak currents that charge and discharge the MOSFET gates to a minimal
physical area by reducing trace length. This confinement decreases the loop
inductance and minimize noise issues on the gate terminals of the MOSFETs.
Refer to sections General
Routing Techniques and MOSFET Placement and Power Stage Routing in
Application Report