CRE 2269

CRE2269 CRE | Alldatasheet

Document overview

• Manufacturer or author: Provided By alldatasheet.com(free datasheet download site)
• PDF pages: 7

Technical content

is a highly intergrated current mode PWM control IC for high performance, low standby power and cost effective offline flyback converter applications in abive 20W power level. 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”birst mode”ti minimize switching loss.Lower standby power and higher conversion efficiency is thus achieved. low startup current and low operating current contribute to a reliable power on startup design withCRE2269. A large value resistor could thus be used in the startup circuit to minimize the standby power. 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 Current Mode PWM Power Switch CRE2269 Extendend Burst Mode Control For Improved Efficiency and Minimum Standby Power Design External Programmable PWM Switching Frequency Exernal Programmable Over Temperature Protection(OTP) Line Compensated Cycle-by-Cycle Over current Threshold Setting For Constant Output Current Limiting Over Universal Input Voltage Range(OCP) With orWithout On-chip VDD OVP for Output Over Voltage Protection Low VIN/VDD Startup Current(5uA) and Low Operating Current(2.4mA) Leading Edge Blanking on Current Sense Input Internal Synchronized Slope Compensation Under Voltage Lockout with Hysteresis(UVLO) Gate Output Maximum Voltage Clamp(18V) Over Load Protection(OLP) CRE Proprietary Frequency Shuffling Technology for Improved EMI Performance Diode reverse recovery. And greatly reduces the external component count and system cost in the design. offers complete protection coverage with automatic self-recovery feature including Cycle-by-Cycle 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 to maximum 18V to protect the power MOSFET. EMI performance is achieved with CRE proprietary frequency shuffking technique together with soft switching control at the totem pole gate drive output.The tone energy at the totem pole gate drive output. The tone energy at below 20KHZ is minimized in operation. Consequently, audio noise performance is greatly improved. is offered in SOP-8 and DIP-8 packages. CRE2269 Excellent CRE2269 Develop 2015-01-5

R IN bias Develop 2015-01-5

Current Mode PWM Power Switch Semiconductor Inc. Page 3 of 7 TERMINAL ASSIGNMENTS： Absolute Maximum Ratings： VDD VFB TJ VCV Parameter VDD Input Voltage VFB Input Voltage Input Voltage to RI Pin Min/Max Operating Junction Temperature Min/Max StorageTemperature VDD Zener ClampVoltage VDD DC Clamp Current VRT VRT Input Voltage to RT Pin TSTG VCC Value -0.3 — 7 -0.3 — 7 -20 — 150 -55 — 150 Unit 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 anyother conditions beyond those indicated under“recommended operating conditions” is not implied. Exposure to absolute maximum-rated conditions for extended periods may affect device reliability. RECOMMENDED OPERATING CONDITION： VDD RI TA Parameter VDD Supply Voltage RT Resistor Value Operating Ambient Temperature Value 12 — 23 -20 — 85 Unit V Kohm Pin Num Pin Name Description GND Ground -0.3 — 7 -0.3 — 7 V V V V V mA V VSENSE Input Voltage to Sense PinVSENSE VRI VRI ESD INFORMATION Parameter UnitValue FB Feedback input pin. PWM duty cycle is determined by voltage level into this pin and current-sense signal level at Pin 6. VIN Connected through a large value resistor to rectified line input for Start upchip supply and line voltage sensing. Internal Oscillator frequency setting pin. A resistor connected between RI and GND sets the PWM frequency.RI Temperature sensing input pin. Connected through a NTC resistor to GND.Once the voltage of the RT pin drops below a fixed limit of 1.05V, PWM output will be disabled.RT Current sense input pin. Connected to MOSFET current sensing resistor node.SENSE DC power supply pin. Totem-pole gate drive output for power MOSFET. VDD GATE VESD-HBM Human Body Model 3 KV VESD-MM Machine Model on All Pins 250 V

ELECTRICAL CHARACTERISTICS

(TA= 25℃, VDD=16V, RI=24Kohm if not otherwise noted) Symbol Parameter Test Conditions Min Typ Max Unit Supply Voltage (VDD) I_VDD_Startup VDD Start up VDD=15V Measure - 5 20 uA CRE2269 Develop 2015-01-5

25.0 Current Mode PWM Power Switch CRE2269 Develop 2015-01-5 page4of7

Current Mode PWM Power Switch Semiconductor Inc. Page 5 of 7 △f_Temp Frequency Temperature Stability △f_VDD Frequency Voltage Stability VDD = 12-25V - 3 - % RI_range Operating RI Range 12 24 60 Kohm V_RI_open RI open load voltage - 2.0 - V F_BM Burst Mode Base Frequency - 21 - KHz DC_max - 78 - % DC_min - - 0 % Gate Drive Output (GATE) VOL Output Low Level Io = -20 mA - - 0.15 V VOH Output High Level Io = +20 mA 11.5 - - V VG_Clamp Output Clamp Voltage Level VDD=20V - 17.8 - V T_r Time CL = 1nf - 140 - nSec T_f Output Falling Time CL = 1nf - 40 - nSec I_RT of RT pin 74 75 76 uA VTH_OTP Voltage - 1.1 - V VTH_OTP_off Threshold Voltage - 1.3 - V V_RT_Open Voltage 3.56 3.58 3.60 V Frequency Shuffling △f_OSC Frequency Modulation range/Base frequency -3 - 3 % Freq_Shuffling Shuffling Frequency RI = 24Kohm - 32 - HZ Output Rising Over Temperature Protection Output Current OTP Threshold OTP Recovery RT Pin Open CRE2269 Develop 2015-01-5

Current Mode PWM Power Switch Semiconductor Inc. Page 6 of 7 OPERATION DESCRIPTION The CRE2269 is a highly integrated PWM to minimize the switching loss thus reduce the controller IC optimized for offline flyback converter standby power consumption to the greatest applications in above 20W power range.The extend. The nature of high frequency switching extended burst mode control greatly reduces the also reduces the audio noise at any loading standby power consumption and helps the design conditions. easily meet the international power conservation requirements. A resistor connected between RI and GND sets the constant current source to charge/discharge the internal cap and thus the PWM oscillator Startup current of CRE2269 is designed to be very frequency is determined. The relationship between low(5uA) so that VDD could be charged up above RI and switching frequency follows the below UVLO threshold level and device starts up quickly. equation within the specified RI in Kohm range at Alarge value startup resistor can therefore be used nominal loading operational condition.to minimize the power loss yet reliable startup in application. For AC/DC adaptor with universal input range design, a 2 MΩ, 0.125W startup resistor Cycle-by-Cycle current limiting is offered in could be used together with a VDD capacitor to CRE2269 current mode PWM control. The switch provide a fast startup and yet low power dissipation current is detected by a sense resistor into the designsolution. sense pin. An internal leading edge blanking circuit chops off the sense voltage spike at initial MOSFET on state due to Snubber diode reverse The Operating current of CRE2269 is low at recovery so that the external RC filtering on sense 2.3mA. Good efficiency is achieved with CRE2269 input is no longer needed. The current limit low operating current together with extended burst comparator is disabled and cannot turn off the mode control schemes external MOSFET during the blanking period. The PWM duty cycle is determined by the current At zero load or light load condition, most of the sense input voltage and the FB input voltage.power dissipation in a switching mode power according to the loading condition. At from no load Built-in slope compensation circuit adds voltage to light/medium load condition, the FB input drops ramp onto the current sense input voltage for below burst mode threshold level (2.2V). Device PWM generation. This greatly improves the close enters Burst Mode control. The Gate drive output loop stability at CCM and prevents the sub-switches only when VDD voltage drops below a harmonic oscillation and thus reduces the output preset level and FB input is active to output an on ripple voltage.state. Otherwise the gate drive remains at off state ◆ Oscillator Operation ◆ Startup Current and Start up Control ◆Current g Sensing d and g Leading Edge Blanking ◆ Operating Current ◆ Burst e Mode Operation ◆ Frequency shuffling for EMI improvement ◆ Internal Synchronized Slope Compensation CRE2269 Develop 2015-01-5

Current Mode PWM Power Switch Semiconductor Inc. Page 7 of 7 CRE2269 ◆ Gate ◆ Over e Temperature Protection ◆ Protection Controls voltage lockout.(UVLO). The OCP threshold is CRE2269 Gate is connected to an external input line voltage adjusted to compensate the MOSFET gate for power switch control. Too weak increased output current limit at higher voltage the gate drive strength results in higher conduction caused by inherent Over-Current sensing and and switch loss of MOSFET while too strong gate control delay. A constant output power limit is drive output compromises the EMI. A good tradeoff achieved with recommended reference design on is achieved through the built-in totem pole gate CRE2269. At overload condition when FB input design with right output strength and dead time voltage exceeds power limit threshold value for control. The low idle loss and good EMI system more than 80mS, control circuit reacts to shut design is easier to achieve with this dedicated down the output power MOSFET. Device restarts control scheme. An internal 17.8V clamp is added when VDD voltage drops below UVLO for MOSFET gate protection at higher than limit.Similarly, control circuit shuts down the power expected VDD input. MOSFET when an Over Temperature condition is detected. CRE2269 resumes the operation when temperature drops below the hysteresis An NTC resistor in series with a regular resistor value.VDD is supplied with transformer auxiliary should connect between RT and GND for winding output. It is clamped when VDD is higher temperature sensing and protection. NTC resistor than 37V. The power MOSFET is shut down whenvalue becomes lower when the ambient VDD drops below UVLO limit and device enters temperature rises. With the fixed internal current power on start-up sequence thereafter.IRT flowing through the resistors, the voltage at RT pin becomes lower at high temperature. The internal OTP circuit is triggered and shutdown the MOSFET when the sensed input voltage is lower than VTH_OTP. Good system reliability is achieved with CRE2269 ’ s rich protection features including Cycle-by-Cycle current limiting (OCP), Over Load Protection (OLP), over temperature protection (OTP), on-chip VDD over voltage protection (OVP,optional) and under Develop 2015-01-5