SG3845G Datasheet | System General

Product Specification Bi CMOS Green-Mode PWM Controllers SG3842G/ 3843G/ 3844G/ 3845G start-up current has been reduced to 5u A, and the minimum operating current has been reduced to 5m A. Each SG384x G 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 SG384x G controller acts as a fixed frequency PWM controller. The PWM frequency can be easily programmed by changing external RT and CT values. The SG384x G includes two Green-mode functions that dramatically reduce power usage, helping the power supply ply 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. SG384x G controllers also e with Over Voltage Protection (OVP). This shuts down PWM output if the supply voltage ever exceeds 27V. The SG384x G series es in 8-pin DIP and SOP packages. Features 384x series pin-to-pin patible Linearly decreasing PWM frequency Burst-mode at low/zero load 5u A start-up current 5m A operating current Vcc over voltage protection Cycle-by-cycle current limiting Zero cross-conduction Slew rate controlled high current totem pole output Fast current sense propagation delay Under voltage lockout (UVLO) with hysteresis APPLICATIONS Switching mode power supplies Power converters DESCRIPTION The SG348x G series of current-mode PWM...