Timeline for Power switch for PWM not functioning as expected
Current License: CC BY-SA 4.0
9 events
| when toggle format | what | by | license | comment | |
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| Aug 31 at 2:29 | comment | added | BK303 | the existing traces look appropriate for 250 to 500mA, and it's common to expand power traces or planes to use up more space at end of layout during cleanup to minimize power loss. I don't think D2 is going to help, as the U2 power switch would already stop back-current from entering the microprocessor (and power LED) if a power source was accidentally connected to the output instead of input. Advised protection is to add zener diode or transient voltage suppressor (TVS) with voltage rating a little higher than the maximum input voltage back-biased onto the Vout rail (where C1 was). | |
| Aug 29 at 14:58 | comment | added | ceej12 | And for max current, the light panel should only use a max of 250mA, and the Pi shouldn't be using much either. I used Digikey's trace calculator to size them, but I had to guess on some of the values. Do you think they're properly sizes for <500mA? Thanks for everyone's help! | |
| Aug 29 at 14:53 | comment | added | ceej12 | As for your other questions/comments, the diode D2 was in the original design, so I'm not certain, but I think it's to prevent powering things if you were to plug the power cable into the wrong place (PWM_OUT). That way the on-board LED would only light if the power was in the right plug. Under normal operation, would it be a problem? | |
| Aug 29 at 14:48 | comment | added | ceej12 | Yep, you were right. The pins had continuity as you expected. I de-soldered the BTS6143, cut the traces, and routed things manually and it now works, properly blinking the light! So much for "Built & Verified by Ultra Librarian." Thanks for your help! | |
| Aug 29 at 14:42 | vote | accept | ceej12 | ||
| Aug 29 at 5:23 | comment | added | BK303 | note, added to answer a method to verify pinout with spare part by continuity checks (pins 3-to-Tab and then pins 1-to-5). Just want to make sure @ceej12 is aware of that late hint. | |
| Aug 29 at 5:15 | history | edited | BK303 | CC BY-SA 4.0 |
added 153 characters in body
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| Aug 29 at 5:01 | history | edited | BK303 | CC BY-SA 4.0 |
clarity, typos
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| Aug 29 at 4:54 | history | answered | BK303 | CC BY-SA 4.0 |