CRE6559

CRE6559 CRE | Alldatasheet

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CRE6559 FREQ SHUFFLINGCRE6559 FREQ SHUFFLING CRE6559 is offered in DIP-8 package. CRE6559 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 fiyback converter applications in sub 30W range CRE6559 offers complete protection coverage with Fixed 65KHz Switching Frequency ACL ACN F1 D1 R1 T1 4 5 GND VDDG VDD FB DRAIN SENCE DRAIN DRAIN GND GND C4 U2 R7 R8 R9 R10 R11 SGND C1 C2 CRE6559 Develop 2015-01-5

CRE6559 FREQ SHUFFLINGCRE6559 FREQ SHUFFLING The CRE6559 is offered in DIP8package as CRE6559:Product Name CRE6559 IC DC power supply Input VDDG Develop 2015-01-5

CRE6559 FREQ SHUFFLINGCRE6559 FREQ SHUFFLING CRE6559 30W 24W Current Reference Soft Driver VDDG Drain Power MOSFET R S Q OSC burst mode Soft- OCP Slope compensation LEB SENSE VthCPL PWM Comparetor 50ms OLP GND 5.7V FB Burst mode VDD Internal supply UVLO POR VDD clamper start 6/7/8 Close Develop 2015-01-5

CRE6559 FREQ SHUFFLINGCRE6559 FREQ SHUFFLING Develop 2015-01-5

2.0 CRE6559 FREQ SHUFFLINGCRE6559 FREQ SHUFFLING Develop 2015-01-5

CRE6559 FREQ SHUFFLINGCRE6559 FREQ SHUFFLING Develop 2015-01-5

CRE6559 FREQ SHUFFLINGCRE6559 FREQ SHUFFLING The CRE6559 is a low power off-line PWM Switcher optimized for off-line fly back converter applications in sub 30W power range. The ”Extended burst mode” control greatly reduces the standby power consumption and help the design easily to meet the international power conservation requirements. Startup current of CRE6559 is designed to be very low so that VDD could be charged up above UVLO threshold level and device starts up quickly. A large value startup resistor can therefore be used to minimize the power loss yet achieve a reliable startup in application. For AC/DC adaptor with universal input range design, a 2M , 1/8Wstartup resistor could be used together with a VDD capacitor to provide a fast startup and yet low power dissipation design solution. Ω The Operating current of CRE6559 is low at 2mA.Good efficiency is achieved with CRE6559low operating current together with the “Extended burst mode” control features. CRE6359 features an internal 4ms soft start to soften the electrical stress occurring in the power supply during startup. It is activated during the power on sequence. As soon as VDD reaches UVLO(OFF), the peak current is gradually increased from nearly zero to the maximum level of 0.83V, Every restart up is followed by a soft start. The frequency Shuffling (switching frequency modulation) is implemented in CRE6559. The oscillation frequency is modulated so that the tone energy is spread out.. The spread spectrum minimizes the conduction band EMI and therefore eases the system design. At light load or zero load condition, most of the power dissipation in a switching mode power supply is from switching loss on the mosfet, the core loss of the ransformer and the loss on the snubber circuit. The magnitude of power loss is in proportion to the switching frequency. Lower switching frequency leads to the reduction on the power loss and thus conserves the energy. The switching frequency is internally adjusted at no load or light load condition. The switch frequency reduces at light/no load condition to improve the conversion efficiency. At light load or no load condition, the FB input drop below burst mode threshold level and device enters Burst Mode control. The Gate drive output switches only when VDD voltage drop below a preset level and FB input is active to output an on state. Otherwise the gate drive remains at off state to minimize the switching loss and reduces the standby power consumption to the greatest extend.The switching frequency control also eliminates the audio noise at any loading conditions. The switching frequency of CRE6559 is internally fixed at 65KHZ. No external frequency setting components are required for PCB design simplification Cycle-by-Cycle current limiting is offered in CRE6559 current mode PWM control. The switch current is detected by a sense resistor into the sense pin. An internal leading edge blanking circuit chops off the sensed voltage spike at initial internal power MOSFETon state due to snubber diode reverse recovery and surge gate current of internal power MOSFET so that the external RC filtering on sense input is no longer needed. The current li comparator is disabled and cannot turn off the blanking period. The PWM duty cycle is determined by the current sense input voltage and the FB input Develop 2015-01-5

Built-in slope compensation circuit adds voltage ramp onto the current sense input voltage for PWM generation. This greatly improves the close loop stability at CCM and prevents the sub-harmonic oscillation and thus reduces the output ripple voltage. The internal power MOSFET in CRE6559 is driven by a dedicated gate driver for power switch control. Too weak the gate drive strength results in higher conduction and switch loss of MOSFET while too strong gate drive results the compromise of EMI. A good tradeoff is achieved through the built-in totem pole gate design with right output strength and dead time control. The low idle loss and good EMI system design is easier to achieve with this dedicated control scheme. In addition to the gate drive control scheme mentioned, the gate drive strength can also be adjusted externally by a resistor connected between VDD and VDDG, the falling edge of the Drain output can be well controlled. It provides great flexibility for system EMI design. Good power supply system reliability is achieved with its rich protection features including Cycle- by-Cycle current limiting(OCP),Over Load Protection(OLP)and over voltage clamp, UnderVoltage Lockout onVDD(UVLO). With Proprietary technology, the OCP is line voltage range. At overload condition when FB input voltage exceeds power limit threshold value for more than TD_PL, control circuit reacts to shut down the switcher. Switcher restarts when VDD voltage drop below UVLO limit. VDD is supplied by transformer auxiliary winding output. It is clamped when VDD is higher than 30V .The output of CRE6559 is shut down when VDD drop below UVLO_ON limit and Switcher enters power on start-up sequence. CRE6559 FREQ SHUFFLINGCRE6559 FREQ SHUFFLING Develop 2015-01-5

CRE6559 FREQ SHUFFLINGCRE6559 FREQ SHUFFLING Develop 2015-01-5