Use Equation 34 to estimate the output capacitance required to manage the output voltage
overshoot during a load-off transient of 10A, assuming a load transient deviation
specification of 100mV.
Equation 34.
Noting the voltage coefficient of ceramic
capacitors where the effective capacitance decreases significantly with applied voltage,
select four 47µF, 10V, X7R, 1210 ceramic output capacitors for each channel. According to
the design tool from the capacitor vendor, these capacitors are each effectively 32µF and
41µF at 5V and 3.3V DC voltage, respectively.
Use Equation 35 to estimate the peak-to-peak output voltage ripple of channel 1 at
nominal input voltage.
Equation 35.
where
RESR is the effective
equivalent series resistance (ESR) of the output capacitors.
128µF is the total effective
(derated) ceramic output capacitance at 5V.
Use Equation 36 to calculate the output capacitor RMS ripple current at maximum input
voltage. Verify that it is within the capacitor ripple current rating.