| ??? 05/01/11 03:12 Modified: 05/01/11 03:17 Read: times |
#182134 - there's an old "standard" ... Responding to: ???'s previous message |
The NSC-recommended value (from and old app-note) was 6000 uF/volt-of-ripple/ampere of current, the latter value being the tolerable ripple at the input of the regulator. Keep in mind that this refers to the input of a linear (probably also an LDO) regulator.
I'd caution you against having too much capacitance, as it means too slow a rise and fall time on Vcc. The typical output cap on the older (non-LDO) linear regulators was a 2.2 uF cap. The rest of the capacitance was distributed as 0.1 or 0.01 uF cap's throughout the boards Vcc-to-Gnd capacitance. Today I use 220 pF rather than 0.01 uF, and lots of them. You'll have to figure out for yourself what the tolerable rise and fall times are, as there's little guidance in the manufacturers' specifications. RE |
| Topic | Author | Date |
| LDO/Capacitor | 01/01/70 00:00 | |
| It seems... | 01/01/70 00:00 | |
| there's an old "standard" ... | 01/01/70 00:00 | |
| Any other LDO | 01/01/70 00:00 | |
| LP38502, LP38692, ... | 01/01/70 00:00 | |
| Thanks | 01/01/70 00:00 | |
| Formula and parentheses | 01/01/70 00:00 | |
| You're right, but that wasn't the point | 01/01/70 00:00 | |
| Did you actually read? | 01/01/70 00:00 | |
| I did read it, but incorrectly | 01/01/70 00:00 | |
Easy to go wrong with multiple divisions | 01/01/70 00:00 |