BP3378AD is a single-stage APFC high-precision primary-side feedback LED constant current control chip compatible with PWM/analog dimming signals, supporting dimming and extinguishing. It is suitable for a full range of input voltages from 90Vac to 277Vac. The BP3378AD chip adopts a control mechanism of fixed on-time, which can achieve high PF for power factor correction. The built-in THD optimization module of BP3378AD further reduces THD. The switch operates in critical conduction mode, reducing switching losses and EMI and improving the utilization rate of the transformer.