Timeline for Improve Brightness in LED Multiplex
Current License: CC BY-SA 4.0
5 events
| when toggle format | what | by | license | comment | |
|---|---|---|---|---|---|
| Feb 28, 2019 at 6:51 | comment | added | Joseph143 | I loaded my matrix as in my first schematic.When The load current reaching 2A rating the B772 transistors are getting really hot Also the ULN also getting heat.I'm planing to redesign the circuit to make it a proper 5V design by adding IRF9530 mosfets to row side & replace all ULN2803 with low saturation BJTs.TO drive the IRF9530 can I directly drive from PIC pin via a 100R & the Gate will pull up by a 10K? | |
| Feb 27, 2019 at 15:47 | comment | added | Simon B | @Joseph143 I'd be wary of eliminating the resistors entirely, as they are what limits the current. Everything else is just voltage drops in semiconductors. You may get away with short pulses of 320mA, but at the cost of shorter LED life. that's why you really need LEDs with datasheets. Those normally give ratings for constant and pulsed current. | |
| Feb 27, 2019 at 3:00 | comment | added | Joseph143 | So that means 20mA X 16 = 320mA I should supply to LED? | |
| Feb 27, 2019 at 2:49 | comment | added | Joseph143 | You are correct.When I short circuit the R3 (27 Ohms) The brightness increases. | |
| Feb 26, 2019 at 22:04 | history | answered | Simon B | CC BY-SA 4.0 |