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OB2287
High Performance Current Mode PWM Controller GENERAL DESCRIPTION
OB2287 is a highly integrated current mode PWM controller for medium to large power offline flyback converter applications. OB2287 enhances On-Bright’s PWM controller series by offering the Brownout Detection and Protection (BOP). OB2287 offers comprehensive protection coverage including Cycle-by-Cycle current limiting, internal Power-On Soft Start, VDD Under Voltage Lockout (UVLO), VDD Over Voltage Protection(OVP), VDD Clamp, Gate Clamp, Over Load Protection(OLP), Over Temperature Protection (OTP), Brownout Protection (BOP). OB2287 also features protections against pin open and short on selected pins. On-Bright’s proprietary OCP compensation can compensate CCM and DCM mode difference when used in universal AC input applications. Moreover, an internal 1-second restart timer prevents permanent OLP latch when the supply of the controller is provided by other DC sources. In applications where supply is self biased by auxiliary winding, this restart timer will not be triggered. To achieve good EMI performance, On-Bright’s proprietary built-in frequency shuffling is provided, together with soft switching control at the totem pole gate drive output. To meet the increasing stringent standby power requirements, in light or No load, OB2287 operates in On-Bright’s proprietary “Extended Burst Mode” without audible noise. OB2287 is offered in SOP-8 and DIP-8 packages.
FEATURES
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TYPICAL APPLICATION
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APPLICATIONS
Offline AC/DC flyback converter for ■ Printer ■ Adaptor ■ LCD Monitor/TV/PC/Set-Top Box Power Supplies ■ Open-frame SMPS
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AC Line Brownout Detection & Protection (BOP) Latch-off Mode Fault Protection Internal Restart Timer All pins floating protection and RI short protection Proprietary Extended Burst Mode Control For Improved Efficiency and Minimum Standby Power Design Audio Noise Free Operation External Programmable PWM Switching Frequency Built-in Frequency Shuffling for Better EMI Internal Leading Edge Blanking Proprietary OCP Compensation for Universal AC Input Range High Precision Reference Voltage for OTP and Brownout Protection Power-On Soft Start Internal Synchronized Slope Compensation 1A Peak Current Drive Sink Capability
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OB_DOC_DS_8700
Free Datasheet http://www.datasheetlist.com/
OB2287
High Performance Current Mode PWM Controller
Package
RθJA (°C/W)
GENERAL INFORMATION
Pin Configuration The pin map of OB2287 in DIP8 and SOP8 package is shown as below.
DIP8 SOP8
90 150
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Package Dissipation Rating
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Ordering Information Part Number Description OB2287AP DIP8, Pb-free OB2287CP SOP8, Pb-free Note: All Devices are offered in Pb-free Package if not otherwise
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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Absolute Maximum Ratings Parameter Value VDD Clamp Voltage 31 V VDD Clamp Continuous 10 mA Current VFB Input Voltage -0.3 to 7V VSENSE Input Voltage to Sense -0.3 to 7V Pin VRT Input Voltage to RT Pin -0.3 to 7V VRI Input Voltage to RI Pin -0.3 to 7V Min/Max Operating Junction -20 to 150 oC Temperature TJ Min/Max Storage Temperature -55 to 150 oC Tstg Lead Temperature (Soldering, 260 oC 10secs) Note: Stresses beyond those listed under “absolute maximum
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OB_DOC_DS_8700
Free Datasheet http://www.datasheetlist.com/
OB2287
High Performance Current Mode PWM Controller
Marking Information
TERMINAL ASSIGNMENTS
Pin Num 1 2 3 Pin Name GND FB BO I/O P I I/O
4 5 6 7 8
RI RT SENSE VDD GATE
I I I
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Description Ground Feedback input pin. PWM duty cycle is determined by voltage level into this pin and current-sense signal level at Pin 6. Connected a resistor divider from line voltage to this pin to detect line voltage. If this pin drops below 1.05V and lasts 50ms, PWM output will be disabled. When brownout is triggered, this pin will source an internal trimmed current for brownout hysteresis programming. Internal Oscillator frequency setting pin. A resistor connected between RI and GND sets the PWM frequency. Dual function pin. Either connected through a NTC resistor to GND for over temperature protection control or used as the latch shutdown control input. Current sense input pin. Connected to MOSFET current sensing resistor node. DC power supply pin. Totem-pole gate drive output for power MOSFET.
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OB_DOC_DS_8700
Free Datasheet http://www.datasheetlist.com/
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OB2287
High Performance Current Mode PWM Controller BLOCK DIAG.