资 源 简 介
OB2278 is a highly integrated current mode PWMcontrol IC opTImized for high performance, lowstandby power and cost effecTIve offline flybackconverter applicaTIons.PWM switching frequency at normal operaTIon isexternally programmable and trimmed to tight range.At no load or light load condition, the IC operates inextended ‘burst mode’ to minimize switching loss.Lower standby power and higher conversionefficiency is thus achieved.VDD low startup current and low operating currentcontribute to a reliable power on startup design withOB2278. A large value resistor could thus be used inthe startup circuit for reduced power loss.The internal slope compensation improves systemlarge signal stability and reduces the possible subharmonicoscillation at high PWM duty cycle output.Leading-edge blanking on current sense inputremoves the signal glitch due to snubber circuit diodereverse recovery and greatly reduces the externalcomponent count and system cost in the design.OB2278 offers comprehensive protection coverageincluding Cycle-by-Cycle current limiting(OCP),VDD Under Voltage Lockout(UVLO), VDD OverVoltage Protection(OVP), VDD Clamp, Gate Clamp,Over Load protection(OLP) and Over Temperatureprotection (OTP).OB2278 offers 3 different version with selectiveprotections set as latch shutdown mode. V versionOB2278 has OVP Latch shutdown only. T versionOB2278 supports both OVP and OTP latch shutdown.L version OB2278 provides all OVP, OTP and OLPlatch shutdown control.Excellent EMI performance is achieved with softswitching control at the totem pole gate drive output.
