OB2269CP Integrated Circuit Chip Current Mode PWM Controller

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OB2269C

Current Mode PWM Controller

GENERAL DESCRIPTION

OB2269C 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 externally programmable and 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 design with OB2269C. A large value resistor could thus be used in the startup circuit to minimize the standby power.

The internal slope compensation improves system large signal stability and reduces the possible subharmonic oscillation at high PWM duty cycle output. Leading-edge blanking on current sense input removes the signal glitch due to snubber circuit diode reverse recovery. This greatly helps to reduce the external component count and system cost in application.

OB2269C offers complete protection coverage with automatic self-recovery feature including Cycle-byCycle current limiting (OCP), over load protection (OLP), over temperature protection (OTP), VDD over voltage protection (OVP) and under voltage lockout (UVLO). The Gate-drive output is clamped at 18V to protect the power MOSFET.

In OB2269C, OCP threshold slope is internally optimized to reach constant output power limit over universal AC input range.

Excellent EMI performance is achieved with OnBright 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 operation. Consequently, audio noise performance is greatly improved.

OB2269C is offered in both SOP-8 and DIP-8 packages.

FEATURES

■ On-Bright Proprietary Frequency Shuffling Technology for Improved EMI Performance

■ Extended Burst Mode Control For Improved Efficiency and Minimum Standby Power Design

■ Audio Noise Free Operation

■ External Programmable PWM Switching Frequency

■ Internal Synchronized Slope Compensation

■ Low VIN/VDD Startup Current(6.5uA) and Low Operating Current (2.3mA)

■ Leading Edge Blanking on Current Sense Input

■ Complete Protection Coverage With Auto SelfRecovery

• External Programmable Over Temperature Protection (OTP)
• With or Without On-chip VDD OVP for System OVP
• Under Voltage Lockout with Hysteresis (UVLO)
• Gate Output Maximum Voltage Clamp (18V)
• Line Compensated Cycle-by-Cycle Overcurrent Threshold Setting For Constant Output Current Limiting Over Universal Input Voltage Range (OCP)
• Over Load Protection. (OLP)

APPLICATIONS

Offline AC/DC flyback converter for

■ Laptop Power Adaptor

■ PC/TV/Set-Top Box Power Supplies

■ Open-frame SMPS

■ Battery Charger

Absolute Maximum Ratings

Note: V_DD_Clamp has a nominal value of 35V.

Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only, functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not implied. Exposure to absolute maximum-rated conditions for extended periods may affect device reliability.

Pin Configuration

The OB2269C is offered in DIP and SOP packages shown as below.