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| LED driver current sense cant find resistor |
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| smile:
Hello, I have LED flood light, the driver is BP3319MB Data sheet https://www.alldatasheet.com/datasheet-pdf/pdf/1141562/BPS/BP3319MB.html There is CS pin to set current level. However in my PCB there are more then one resitor connected to CS pin. So I cant find it. help. Copy paste image URL to see full size version. |
| RJSV:
Wild Guess; (before I go read the spec). I'm thinking that could be SEVERAL separate resistor loads, for controlling one at a time. Such as for selection between Dim, Medium, and Bright. In that case you would likely observe a separate surface mount transistor for each resistor,...with only one of them selected at a time. Maybe try (power off) measure the resistances; my guess would be something like: (R1) at 500 ohm (dim) (R2) at 330 ohm (medium) (R3) at 100 ohm ((brightest) |
| MarkS:
--- Quote from: RJSV on September 24, 2023, 03:53:21 am ---Wild Guess; (before I go read the spec). I'm thinking that could be SEVERAL separate resistor loads, for controlling one at a time. Such as for selection between Dim, Medium, and Bright. In that case you would likely observe a separate surface mount transistor for each resistor,...with only one of them selected at a time. Maybe try (power off) measure the resistances; my guess would be something like: (R1) at 500 ohm (dim) (R2) at 330 ohm (medium) (R3) at 100 ohm ((brightest) --- End quote --- If you trace the circuit, it consists of R1, R2, R13, R14, R15, R16 and D2 and seems to be connected back to the IC through R13. I understand smile's confusion! |
| smile:
--- Quote --- Maybe try (power off) measure the resistances; my guess would be something like: (R1) at 500 ohm (dim) (R2) at 330 ohm (medium) (R3) at 100 ohm ((brightest) --- End quote --- The light has only one mode, not 3. So Why all the resitors? Here is the other side of PCB |
| MarkS:
I wish I could help, but that circuit makes zero sense! I'm waiting for someone to come along and explain it myself. |
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