HIGH PERFORMANCE CURRENT MODE PWM CONTROLLER WITH PEAK LOAD
DESCRIPTION
UTC UC3883 is a highly integrated current mode PWM control IC optimized for high performance, low standby power and cost effective offline flyback converter applications. PWM switching frequency at normal operation is internally fixed and is trimmed to tight range. At no load or light load condition, the IC operates in extended ‘burst mode’ to minimize switching loss. Lower standby power and higher conversion efficiency is thus achieved. VCC low startup current and low operating current contribute to a reliable power on startup and low standby design with UTC UC3883. UTC UC3883 offers complete protection coverage with auto-recovery including Cycle-by-Cycle current limiting (OCP), over load protection (OLP), over temperature protection (OTP) and VCC under voltage lockout (UVLO). It also provides the over voltage protection (OVP) protections with latched shut down. Excellent EMI performance is achieved with UTC proprietary frequency shuffling technique. The tone energy at below 20KHZ is minimized in the design and audio noise is eliminated during operation.
FEATURES
* Power on Soft Start Reducing MOSFET VDS Stress
* Frequency shuffling for EMI
* Extended Burst Mode Control For Improved Efficiency and Minimum Standby Power Design
* Ultra Low Operating Current at Light Load (typical 0.6mA)
* Audio Noise Free Operation
* Normal 65KHz Switching Frequency
* Frequency Triple for peak load (180KHz)
* Adjustable Overload Protection (OLP) delay time
* Comprehensive Protection Coverage VCC Under Voltage Lockout with Hysteresis (UVLO) Cycle-by-cycle over current threshold setting for constant output power limiting over universal input voltage range
Overload Protection (OLP) with autorecovery External (if NTC resistor is connected at CT/RT pin) or internal (if capacitor is connected at CT/RT pin)
Over Temperature Protection (OTP) with autorecovery. VCC Over Voltage Protection (OVP) with latch shut down
