The scenario
Designing an isolated PWM dimming interface for an LED driver where the control signal must be electrically isolated from the power stage.
What is in this drawing
Read the decisions behind it.
01
Discrete optocoupler (LED + phototransistor) for isolation
02
Open-base NPN as phototransistor to couple light
03
Separate ground domains to preserve galvanic isolation
Suitable for low-cost isolated PWM dimming in LED fixtures, using standard components without specialized optocoupler ICs.
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