Overview: Product Specification BiCMOS Green-Mode PWM Controllers SG3842G/ 3843G/ 3844G/ 3845G
start-up current has been reduced to 5uA, and the minimum operating current has been reduced to 5mA. Each SG384xG has a slew rate controlled high current totem pole output, ideally suited for driving a power MOSFET while keeping EMI low. The current-sense propagation delay is typically 50ns, resulting in significantly more effective constant power protection. During normal operation, a SG384xG controller acts as a fixed frequency PWM controller. The PWM frequency can be easily programmed by changing external RT and CT values. The SG384xG includes two Green-mode functions that dramatically reduce power usage, helping the power supply comply with the latest international power saving guidelines. To cut power consumption under light load conditions, the controller’s Green-mode function will linearly decrease the PWM frequency in response to decreases in the output load. Under ultra light-load/zero-load conditions, the RT/CT PWM oscillator periodically shuts down, and enters into Burst-mode. This causes the IC’s supply voltage to begin gradually dropping. Just before the supply voltage drops below the UVLO voltage threshold, the RT/CT PWM oscillator turns back on, to prevent the supply voltage from going below the UVLO voltage. SG384xG controllers also come with Over Voltage Protection (OVP). This shuts down PWM output if the supply voltage ever exceeds 27V. The SG384xG series comes in 8-pin DIP and SOP packages.
