| ??? 04/11/05 17:22 Read: times |
#91387 - part number for Allegro chip? Responding to: ???'s previous message |
Erik Malund said:
For slow raising 5V supply, the port outputs (of some ICs, not all) might be initially at ground, up to a relatively high supply level (about 2-3V for example). In that case, if the 12V (or any voltage at the power section) is already on and the 5V, for some reason, is increased rather slowly, the end load might become active for a short period.
This is solved by Allegro. They have driver chips with a reset input that you can connect to your supervisor output. Then nothing happens till the uC start running. Using a driver chip has an added advantage which is that you can use a driver that make a high input the off state which avoid the little on burst from the reset. Erik That is definitely a nice feature. The LMD18400 which I mentioned previously has two enable facilities which could be connected to a reset line to ensuure the driver remains inactive during reset. However, after reset, it still seems possible that the driver could be in an unpredictable state until you initialize the 8051 outputs it is connected to. Would you provide the part number or data sheet link for the device you mentioned? I am interested in seeing if it offers a way around this situation. Thanks. --Sasha Jevtic |
| Topic | Author | Date |
| Driving 12V Relay W/ 8051 | 01/01/70 00:00 | |
| Ammended Image Post | 01/01/70 00:00 | |
| that get you nowhere. | 01/01/70 00:00 | |
| A few things | 01/01/70 00:00 | |
| No, that is not so. | 01/01/70 00:00 | |
| an 8751, perhaps | 01/01/70 00:00 | |
| Pull Ups and Base Current | 01/01/70 00:00 | |
| ULN2003 | 01/01/70 00:00 | |
| door lock diagram | 01/01/70 00:00 | |
| One more method... | 01/01/70 00:00 | |
| Why not use 2N7000 | 01/01/70 00:00 | |
| 2N7000 Not Good By Itself | 01/01/70 00:00 | |
| You have a point | 01/01/70 00:00 | |
| FET solution | 01/01/70 00:00 | |
| Elegant? | 01/01/70 00:00 | |
| True.. | 01/01/70 00:00 | |
| It Can Be Small | 01/01/70 00:00 | |
| Zetex | 01/01/70 00:00 | |
| Could it be smaller? | 01/01/70 00:00 | |
| Think so. | 01/01/70 00:00 | |
| Onboard Resistors | 01/01/70 00:00 | |
| Digital transistors | 01/01/70 00:00 | |
Missed | 01/01/70 00:00 | |
| an added note | 01/01/70 00:00 | |
| solved by Allegro | 01/01/70 00:00 | |
| part number for Allegro chip? | 01/01/70 00:00 | |
| take your pick | 01/01/70 00:00 | |
| I missed a few | 01/01/70 00:00 | |
| It was a note :) | 01/01/70 00:00 |