Application Note
11 of 63
V 1.2
2018-12-12
5 Output PMIC Controller/ IRPS5401
User guide with DB295 and DB296 demo boards
4
Switcher Operation
The IRPS5401 consists of 4 internal switching regulators (Switchers). SW-A and B are 2 A regulators. SW-C and
D are 4A regulators. SW-A can be configured to drive an external power stage such as the TDA21240
PowerStage or a discrete FET driver with power FET. This output can be designed to deliver up to 50 A. The
DB295 is configured such that SW-A is driving an external TDA21240 PowerStage.
Figure 12
Internal switching regulators
One of the most important considerations for the layout is the path length and loop area for the current path
from the input capacitors to the FET switches. C85 in the figure to the left is a 1
µ
F, 0402 multi-layer ceramic
capacitor (MLCC). It is one of the VIN decoupling caps for SW-D. It is placed adjacent to the VIN pins for SW-D
and is returned to GND through a via. On the bottom of the PCB, C70 and C71 are 10
µ
F MLCC caps that provide
additional decoupling for SW-D. They are arranged at 45° to provide the shortest path length to the GND RTN
vias under the IC.
Figure 13
Layout details
Other important considerations are:
The length and width of the copper connecting the SW Nodes to the inductors. They must be as short as
possible and as wide as possible, and be located only on the top layer
