Current Mode PWM Power Switch Freq Shuffling
OB2358 combines a dedicated current mode PWM
controller with a high voltage power MOSFET. It
is optimized for high performance, low standby
power, and cost effective off-line flyback converter
applications in sub 27W range.
OB2358 offers complete protection coverage with
automatic self-recovery feature including Cycle-by-
Cycle current limiting (OCP), over load protection
(OLP), VDD over voltage clamp and under voltage
lockout (UVLO). Excellent EMI performance is
achieved with On-Bright proprietary frequency
shuffling technique together with soft switching
control at the totem pole gate drive output.
The tone energy at below 20KHZ is minimized in the
design and audio noise is eliminated during operation.
OB2358 is offered in DIP8 package.
■ Power on Soft Start Reducing MOSFET Vds
■ Frequency shuffling for EMI
■ Extended Burst Mode Control For Improved
Efficiency and Minimum Standby Power Design
■ Audio Noise Free Operation
■ Fixed 50KHZ Switching Frequency
■ Internal Synchronized Slope Compensation
■ Low VDD Startup Current and Low Operating
■ Leading Edge Blanking on Current Sense Input
■ Good Protection Coverage With Auto Self-
o VDD Over Voltage Clamp and Under Voltage
Lockout with Hysteresis (UVLO)
o On-Bright Proprietary Line Input Compensated
Cycle-by-Cycle Over-current Threshold Setting
For Constant Output Power Limiting Over
Universal Input Voltage Range.
o Overload Protection (OLP).
o Over voltage Protection(OVP)
Offline AC/DC flyback converter for
■ AC/DC adaptor
■ PDA power supplies
■ Digital Cameras and Camcorder Adaptor
■ VCR, SVR, STB, DVD&DVCD Player SMPS
■ Set-Top Box Power
■ Auxiliary Power Supply for PC and Server
■ Open-frame SMPS
Output Power Table
1. Maximum practical continuous power in an open frame design with sufficient drain pattern as a heat sink, at 50℃ ambient.