Timeline for Controlling 3V3 relay from 2V8 (VL53L1X) GPIO output with PNP transistor
Current License: CC BY-SA 4.0
3 events
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| Jun 15, 2020 at 20:29 | comment | added | Kyle B | It's up to you. Here's the thing - If you do what you're describing, then you are creating a marginal design. Will it work on one unit? Probably. But that trickle current is a variable that depends on factors you won't control such as temperature - You need to ask yourself - If the worst happens, and somebody gets hurt, are you comfortable defending your decision to not include that extra drive transistor during a review of your design by an investigating engineer???? Some people will stand on the edge of the Grand Canyon for the great view. Some people will stand 10 feet back.... | |
| Jun 15, 2020 at 8:48 | comment | added | rejnok | I surely need a relay in this situation, I'm aware of its risks, but during normal operation the relay is not used, or in worst case only small number of times during lifetime of the device. But still I can add second relay to be sure one of them not fail, and even can add software counter of relay usage (sensing GPIO wire). I think there is no need for transistor to be completely off, as the relay coil need relatively high current to switch on. But do you think that constant small residual current can raise the risk of transistor or relay to fail after many months? | |
| Jun 12, 2020 at 14:23 | history | answered | Kyle B | CC BY-SA 4.0 |