The highly integrated SG6902 is designed for power supplies with boost PFC
and flyback PWM. It requires few external components to achieve green mode
operation and versatile protections. It is available in a 20-pin SOIC package.
The proprietary interleave-switching feature synchronizes the PFC and PWM
stages and reduces switching noise. At light loads, the switching frequency is
continuously decreased to reduce power consumption. If output loading is further
reduced, the PFC stage is turned off to reduce power consumption.
For PFC stage, the proprietary multi-vector control scheme provides a fast
transient response in a low-bandwidth PFC loop, in which the overshoot and
undershoot of the PFC voltage are clamped. If the feedback loop is broken, the
SG6902 shuts off PFC to prevent extra-high voltage on output. Programmable
two-level output voltage control reduces the PFC output voltage at low line
input to increase the efficiency of the power supply.
For the flyback PWM, the synchronized slope compensation ensures the
stability of the current loop under continuous-conduction-mode operation.
Built-in line-voltage compensation maintains a constant output power limit.
Hiccup operation during output overloading is also guaranteed.
In addition, SG6902 provides protection functions, such as brownout and RI
pin open/short protections.
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