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| How does this feedback network work? |
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| Red_Micro:
Hello, In the circuit below, what's the function of D18 and C37 at the junction of R24 and R27? Do R24 and R27 look like they are in series with R26? |
| T3sl4co1l:
VFB is the AUX winding, and I guess U1 is a quasi-resonant or BCM controller? Guessing they wanted to adjust the rising and falling timings slightly. Or maybe D18-R24-C37 serves as a snubber for D28 and the winding, and they're just taking feedback from there for whatever reason. Tim |
| Wimberleytech:
I don't get it. R24 appears to be a 205 ohm 1% resistor. :-// |
| bson:
R24 and C37 will make the driver briefly overshoot during start and acceleration. D18 allows fast discharge of C37 when VFB drops, so it doesn't undershoot when slowing. Well, maybe a little due to the diode Vf. |
| Wimberleytech:
--- Quote from: bson on February 28, 2020, 05:51:20 pm ---R24 and C37 will make the driver briefly overshoot during start and acceleration. D18 allows fast discharge of C37 when VFB drops, so it doesn't undershoot when slowing. Well, maybe a little due to the diode Vf. --- End quote --- Is there a reason for the 1% value for R24? |
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