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
o VDD Under Voltage Lockout with
Hysteresis (UVLO)
o Cycle-by-cycle over current threshold
setting for constant output power limiting
over universal input voltage range
o Overload Protection (OLP) with auto-
recovery
o Over Temperature Protection (OTP) with
latch shut down
o VDD Over voltage Protection(OVP) with
latch shut down
o Adjustable OVP through external Zener
APPLICATIONS
Offline AC/DC flyback converter for
■ Battery Charger
■ Power Adapter
■ Set-Top Box Power Supplies
■ Open-frame SMPS
TYPICAL APPLICATION
©On-Bright Electronics
Confidential
-1-
Preliminary Datasheet
OB_DOC_DS_227305
Free Datasheet http://www.datasheet4u.com/
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