OB2273 High Performance Current Mode PWM Controller
General Description
OB2273 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. VDD low startup current and low operating current contribute to a reliable power on startup and low standby design with OB2273. OB2273 offers complete protection coverage with auto-recovery including Cycle-by-Cycle current limiting (OCP), over load protection (OLP), and VDD under voltage lockout (UVLO). It also provides the protections with latched shut down including over temperature protection (OTP), and over voltage (fixed or adjustable) protection (OVP). Excellent EMI performance is achieved with On-Bright proprietary frequency shuffling technique. The tone energy at below 20KHZ is minimized in the design and audio noise is eliminated during operation. OB2273 is offered in SOT23-6 and DIP-8 package.
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
Audio Noise Free Operation
Fixed 65KHZ Switching Frequency
Comprehensive Protection Coverage
VDD 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
Over Temperature Protection (OTP) with latch shut down
VDD Over voltage Protection(OVP) with latch shut down
Adjustable OVP through external Zener
Applications
Offline AC/DC flyback converter for
Battery Charger
Power Adapter
Set-Top Box Power Supplies
Open-frame SMPS
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