| ??? 01/27/06 14:38 Modified: 01/27/06 14:39 Read: times |
#108513 - Also depends on transistor speed Responding to: ???'s previous message |
Erik said:
SO, the internal diodes WILL protect the transistor, but the EMI will be dramatic if the realys are not VERY close. This is an interesting issue. It's often overlooked, that the diode must be faster than the transistor! Otherwise a high inductive kick is produced! If you have a rather slow transistor, like the ULN2003 Darlington, then a standard diode is enough. In this case also the EMI is rather low, because the switching-off of current goes rather slowly. Here the diode can rest in the ULN2003 package. But if you have a fast transistor, then you also need a fast diode and enormous EMI is produced if the diode is not placed directly at the coil!! Kai |
| Topic | Author | Date |
| Relay board diagram | 01/01/70 00:00 | |
| Just search for, "Relay" !! | 01/01/70 00:00 | |
| andy Neil | 01/01/70 00:00 | |
| Relay ratings | 01/01/70 00:00 | |
| ULN2803,ULN2003 | 01/01/70 00:00 | |
| more on relay ratings | 01/01/70 00:00 | |
| Yes of course | 01/01/70 00:00 | |
| internal diodes | 01/01/70 00:00 | |
| ULN2003's doesn't easily burn | 01/01/70 00:00 | |
| Uce saturation voltage is rather high | 01/01/70 00:00 | |
| there is an alternative, search for it | 01/01/70 00:00 | |
| I agree | 01/01/70 00:00 | |
| That is bad design | 01/01/70 00:00 | |
| ULNs resist more... | 01/01/70 00:00 | |
| I would never suggest 74HC buffers for d | 01/01/70 00:00 | |
| Yes , you didn't | 01/01/70 00:00 | |
| I would like to see where that is, pleas | 01/01/70 00:00 | |
correct link | 01/01/70 00:00 | |
| Bad Design? | 01/01/70 00:00 | |
| naah | 01/01/70 00:00 | |
| Also depends on transistor speed | 01/01/70 00:00 | |
| valid issue, but not that, now another | 01/01/70 00:00 | |
| Indeed | 01/01/70 00:00 | |
| Serial | 01/01/70 00:00 | |
| How much current? | 01/01/70 00:00 | |
| allegro | 01/01/70 00:00 | |
| and infineon | 01/01/70 00:00 |