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OB2353 Low Power Off Line SMPS Switcher Freq Shuffling
GENERAL DESCRIPTION
OB2353 combines a dedicated current mode PWM controller with integrated high voltage power MOSFET .It is optimized for high performance low standby power and cost effective offline flyback converter applications in sub 10W range. OB2353 PWM frequency operates in the fixed and trimmed . At no load or light load the frequency is internal adjusted, 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 OB2353. 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(CS) input removes the signal glitch due to snubber circuit diode reverse recovery and thus greatly reduces the external component count and system cost in the design. OB2353 offers complete protection coverage with automatic self-recovery feature including Cycle-byCycle 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 www.DataSheet4U.com design and audio noise is eliminated during operation. OB2353 is offered in SOP-8 package.
FEATURES
Optimized for sub 10W Applications Single Chip 650V Sense FET Power Switch for Package. ■ Soft Start with 4mS ■ 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 Current ■ Leading Edge Blanking on Current Sense Input ■ Good Protection Coverage With Auto SelfRecovery 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)
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APPLICATIONS
Offline AC/DC flyback converter for ■ Battery Charger ■ PDA power supplies ■ Digital Cameras ■ Power Adaptor ■ Set-Top Box Power Supplies ■ Open-frame SMPS
TYPICAL APPLICATION
©On-Bright Electronics -1-
Confidential OB_DOC_DS_5301
OB2353 Low Power Off Line SMPS Switcher Freq Shuffling
GENERAL INFORMATION
Pin Configuration The OB2353 is offered in SOP8 package, shown as below. Part Number OB2353CP OB2353CP/A Description SOP8, Pb-free SOP8,Pb-free,Tape&Reel
Package Dissipation Rating
RθJA (°C/W)
SOP8
150
Absolute Maximum Ratings Parameter Value Drain Input Voltage 650V VDD Input Voltage 32 V VDD-G Input Voltage 32 V VDD Input DC Current 10mA VFB Input Voltage -0.3 to 7V VSENSE Input Voltage to Sense -0.3 to 7V Pin Min/Max Operating Junction -20 to 150 oC Temperature TJ Min/Max Storage Temperature -55 to 160 oC Tstg Lead Temperature (Soldering, 260 oC 10secs) Note: 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.
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Ordering Information
©On-Bright Electronics -2-
Confidential OB_DOC_DS_5301
OB2353 Low Power Off Line SMPS Switcher Freq Shuffling
Marking Information
X: C for SOP8; P: Pb-free Package; Y: Year Code (0-9) WW: Week Code (1-52) s: Optional Internal Code
TERMINAL ASSIGNMENTS
Pin Name GND FB
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I/O P I P I P P
VDD-G SENSE VDD Drain
Description Ground Feedback input pin. The PWM duty cycle is determined by voltage level into this pin and the current-sense signal at Pin 3. Power Supply specially for Internal Gate Driver Current sense input pin. Chip DC power supply pin. The Drain pin is designed to connect directly to the primary lead of the transformer and is capable of switching a maximum of 650V
©On-Bright Electronics -3-
Confidential OB_DOC_DS_5301
OB2353 Low Power Off Line SMPS Switcher Freq Shuffling
BLOCK DIAGRAM
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©On-Bright Electronics -4-
Confidential OB_DOC_DS_5301
OB2353 Low Power Off Line SMPS Switcher Freq Shuffling
ELECTRICAL CHARACTERISTICS
(TA = 25OC if not otherwise noted) Symbol Parameter Supply Voltage (VDD) I_VDD_Startup VDD Start up Current I_VDD_Operation Operation Current UVLO(ON) VDD Under Voltage Lockout Enter UVLO(OFF) VDD Under Voltage Lockout .