The inductor and the output capacitor together provide a low-pass filter. To simplify the selection process, Table 4 outlines possible inductor and capacitor value combinations for most applications.
Table 4. Matrix of Output Capacitor and Inductor Combinations
| NOMINAL L [µH](2) |
NOMINAL COUT [µF](3)(4) |
| 10 |
22 |
47 |
100 |
| 0.47 |
|
|
|
|
| 1 |
+ |
+(1) |
+ |
|
| 2.2 |
|
|
|
|
(1) Typical application configuration. Other '+' mark indicates recommended filter combinations.
(2) Inductor tolerance and current derating is anticipated. The effective inductance can vary by 20% and –30%.
(3) For low output voltage applications (< 1.8 V), more output capacitance is recommended (usually ≥ 22 μF) for smaller ripple. For output capacitance higher than 47 µF, a feed forward capacitor is needed.
(4) Capacitance tolerance and bias voltage derating is anticipated. The effective capacitance can vary by 20% and –50%.