Input Capacitance; Output Capacitance - Flex ROA128 6016 User Manual

Test Board User Guide BMR47401
11.2

Input capacitance

The ceramic input capacitors should be placed as close as possible to the
VIN/PGND pins to minimize the connection impedance. For the same reason,
multiple vias are placed close to the capacitors' terminals, utilizing inner layers to
connect to input pins of the module.
Note there are places for additional input capacitors on the bottom side of the
board, see section 7.
Placement and connections of the larger bulk input capacitor (used mainly to hold
up the input voltage during large load transients or changes in input voltage)
follows the rules of the ceramic capacitors described above.
11.3

Output capacitance

Ceramic output capacitors are placed close to VOUT pins of the module to handle
the module's output ripple. Polymer capacitor are added to take care of load
transient, see Technical Specification for load transient performance. It is
important to secure low impedance connections
Note there are places for additional output capacitors on the bottom side of the
board, see section 7.
Furthermore, it is important to use planes to distribute the output current to the
load in order to minimize losses and the effective output impedance, providing
good conditions for the module's control loop to compensating for load transient.
See layout top view of ROA 128 6016 for more information.
28701-ROA1286016 Rev A 2021/4/25 14 (20)