Timeline for PCB trace width and high current with MOSFETs
Current License: CC BY-SA 4.0
11 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Jan 15, 2024 at 15:05 | comment | added | Tim Williams | And like I said, inductance is the bigger deal. A 10mm wide trace has about 1/10 the inductance of a 1mm trace. And a 1cm long trace has 1/10 the inductance of a 10cm long trace. Keep it wide and flat, and components close together (short loop length). There aren't design rules for this. Only engineering experience. | |
| Jan 15, 2024 at 9:29 | comment | added | Andr7 | Thanks! @jusaca | |
| Jan 15, 2024 at 7:11 | comment | added | jusaca | You can use copper sheet resistance for fast approximation. 35 µm copper has 0.5 mOhm / square. So a trace with double the length in comparison to width has 1 mOhm. For 33 mOhm the trace can be 66 times the width. 2 mm width would mean maximum length of 66 mm to stay below 1 V of voltage drop. | |
| Jan 15, 2024 at 7:08 | comment | added | jusaca | As I said, I would decide it by specifying a maximum voltage drop. If for example your pulse voltage can not drop by more than 1V over the trace just calculate 1V / 30A = 33 mOhm maximum. | |
| Jan 15, 2024 at 6:51 | comment | added | Andr7 | @jusaca, how do I decide the acceptable trace resistance? | |
| Jan 15, 2024 at 6:44 | comment | added | jusaca | For µs-long pulses I would design for an acceptable trace resistance and corresponding voltage drop instead of temperature rise. Specify what voltage drop you allow and in combination with your 30A you get a maximum value for the allowed trace resistance. Now you can design trace width too stay below that value. | |
| Jan 15, 2024 at 4:22 | comment | added | Tim Williams | It's most likely not an issue. | |
| Jan 15, 2024 at 4:11 | comment | added | Andr7 | So how should I deal with the trace widths considering my traces lengths are short only? | |
| Jan 15, 2024 at 4:08 | comment | added | Tim Williams | Long traces, where heat only flows laterally out from the trace. | |
| Jan 15, 2024 at 4:06 | comment | added | Andr7 | - my double pulses are in us - what do you mean by temp rise is only valid for long traces? | |
| Jan 15, 2024 at 4:03 | history | answered | Tim Williams | CC BY-SA 4.0 |