| ??? 04/15/07 22:32 Read: times Msg Score: +2 +1 Informative +1 Good Answer/Helpful |
#137302 - It's not my original idea Responding to: ???'s previous message |
Good Idea! It's not my original idea. You'll find it on some LDO datasheets with kind description. This appnote from NS covers whole stories, including the application of ceramic capacitors to LDO. AN1148: Linear Regulators: Theory of Operation and Compensation http://www.national.com/an/AN/AN-1148.pdf Output Capacitor Selection (p7) It must be noted that large (>= 1 uF) ceramic capacitors typically have very low ESR values (< 20 mOhm), and will cause most LDO regulators to oscillate if connected directly to the output (except the LP2985). A ceramic capacitor can be used if some external resistance is added in series with it to increase the effective ESR. Large value ceramics also have a poor tempco (typically Z5U) which means the capacitance will drop in half as the temperature is increased or decreased to the operating limits. Tsuneo |
| Topic | Author | Date |
| Ceramic instead of Tantalum? ESR? | 01/01/70 00:00 | |
| a nice paper related to the topic | 01/01/70 00:00 | |
| Ceramic it is, but.. | 01/01/70 00:00 | |
| LDO regs and ESR | 01/01/70 00:00 | |
| naah, just know-how | 01/01/70 00:00 | |
| Odd | 01/01/70 00:00 | |
| It\\\'s because of chip design | 01/01/70 00:00 | |
| Good Idea! But... | 01/01/70 00:00 | |
| It's not my original idea | 01/01/70 00:00 | |
| Y5V preferred | 01/01/70 00:00 | |
| Still out of stable region at low frequency | 01/01/70 00:00 | |
Only the ESR minimum of cap is what counts | 01/01/70 00:00 |