| ??? 02/20/06 14:08 Read: times Msg Score: +1 +1 Good Answer/Helpful |
#110333 - Remedy Responding to: ???'s previous message |
Sun said:
I plan to use a cap in parallel with the zener, hence forming an RC network with the series resistor. Yes, that's the remedy! Zeners can need several hundreds of nanoseconds to turn-on. Zeners can also turn-on slowly because of their parasitic junction capacitance, which is about 100pF even for a tiny BZX55-C4V7. In combination with a relevant source impedance this also leads to a turn-on delay. Zeners are not suited to protect against ESD for instance, because the turn-on time is way too long. In such cases a transzorb should be used. Don't worry about turn-on time in your case. Take an electrolytic capacitor or another cap in the µF range and you will not have any problems. Kai |
| Topic | Author | Date |
| Zener Turn-on-time | 01/01/70 00:00 | |
| Remedy | 01/01/70 00:00 | |
| Thank You Kai | 01/01/70 00:00 | |
| Divider | 01/01/70 00:00 | |
| Resistor values | 01/01/70 00:00 | |
| Read again my calculation example | 01/01/70 00:00 | |
| drop that stupid resistor to ground | 01/01/70 00:00 | |
| can you draw the schematic? | 01/01/70 00:00 | |
| Assistance required to post Sch | 01/01/70 00:00 | |
| If using "Windows" | 01/01/70 00:00 | |
| Typo Oops | 01/01/70 00:00 | |
| Using a cap is enough | 01/01/70 00:00 | |
| actually for the "typical" use it is not | 01/01/70 00:00 | |
| Less than 1nsec | 01/01/70 00:00 | |
| Resistor instead of the cap | 01/01/70 00:00 | |
| Sch | 01/01/70 00:00 | |
| ALWAYS design to worst case. | 01/01/70 00:00 | |
| Homepage | 01/01/70 00:00 | |
| why is that 1k still there | 01/01/70 00:00 | |
| Aha! | 01/01/70 00:00 | |
Thank you all for your help. | 01/01/70 00:00 |