Datasheet

Data Sheet ADP5033
Rev. F | Page 19 of 28
The peak-to-peak output voltage ripple for the selected output
capacitor and inductor values is calculated using the following
equation:
( )
OUT
SW
IN
OUT
SW
RIPPLE
RIPPLE
CLf
V
Cf
I
V
×××π
≈
××
=
2
28
Capacitors with lower equivalent series resistance (ESR) are
preferred to guarantee low output voltage ripple, as shown in
the following equation:
RIPPLE
RIPPLE
COUT
I
V
ESR ≤
The effective capacitance needed for stability, which includes
temperature and dc bias effects, is a minimum of 7 µF and a
maximum of 40 µF.
The buck regulators require 10 µF output capacitors to guarantee
stability and response to rapid load variations and to transition
into and out of the PWM/PSM modes. In certain applications,
where one or both buck regulators power a processor, the
operating state is known because it is controlled by software.
In this condition, the processor can drive the MODE pin
according to the operating state; consequently, it is possible to
reduce the output capacitor from 10 µF to 4.7 µF because the
regulator does not expect a large load variation when working
in PSM mode (see Figure 47).
Table 10. Suggested 10 μF Capacitors
Vendor Type Model Case Size Voltage Rating (V)
Murata
X5R
GRM188R60J106
0603
6.3
TDK X5R C1608JB0J106K 0603 6.3
Panasonic X5R ECJ1VB0J106M 0603 6.3