CR622X ETC2

Document overview

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Technical content

Nov, 2009 V2.2 1/10 CR622X—CR6221/6224/6228/6229 Green-Power Current Mode PWM Power Switch Feature z Power on Soft Start Reducing MOSFET Vds Stress z Frequency shuffling for EMI z Burst Mode Control For Improved Efficiency and Minimum Standby power Design z Audio Noise Free Operation z Normal 50 KHz Switching Frequency z Internal Synchronized Slope Compensation z Low VDD Startup Current and Low Operating Current z Leading Edge Blanking on Current Sense Input z Pb-Free SOP-8L& DIP-8L z Good Protection Coverage With Auto Self-Recovery ¾ VDD Over Voltage Clamp and Under Voltage Lockout with Hysteresis (UVLO) ¾ Line Input Compensated Cycle-by-Cycle Over-current Threshold Setting For Constant Output Power Limiting Over Universal Input Voltage Range ¾ Overload Protection (OLP) ¾ Over Voltage Protection (OVP)

Applications

z Digital Cameras and camcorder Adaptor z VCR, SVR, STB, DVD & DVCD Player SMPS z Set-Top Box (STB) Power z Auxiliary Power Supply for PC and Server z Open-frame SMPS General Description CR622X 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 flyback converter applications in sub 24W range. CR622X offers complete protection coverage with automatic self-recovery feature including Cycle-by-Cycle current limiting (OCP), over load protection (OLP), VDD over voltage clamp and under voltage lockout (UVLO). Excellent EMI performance is achieved with frequency shuffling technique together with soft switching control at he totem pole gate drive output. CR622X is offered in DIP-8L & SOP-8L package.

CR622X Green-Power Current Mode PWM Power Switch Nov, 2009 V2.2 2/10 Pin Assignment （DIP-8L & SOP-8L） Pin Descriptions Pin Name Description GND Ground FB Feedback input pin. The PWM duty cycle is determined by voltage level into this pin and the current-sense signal at Pin 4. VDD-G Internal Gate Driver Power Supply SENSE Current sense input VDD IC DC power supply Input Drain HV MOSFET Drain Pin. The Drain pin is connected to the primary lead of the transformer. TYPICAL APPLICATION

CR622X Green-Power Current Mode PWM Power Switch Nov, 2009 V2.2 3/10 Block Diagram Simplified Internal Circuit Architecture Absolute Maximum Ratings Parameter Value Drain Voltage (off state) -0.3V to 650V VDD Voltage -0.3V to 30V VDD-G Input Voltage -0.3V to 30V VDD Clamp Continuous Current 10 mA FB Input Voltage -0.3V to 7V Sense Input Voltage -0.3V to 7V Min/Max Operating junction Temperature TJ -20℃ to 150℃ Min/Max Storage Temperature Tstg -55℃ to 160℃ Lead Temperature (Soldering, 10secs) 260℃ Note: Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. Exposure to absolute maximum-rated conditions for extended periods may affect device reliability. Output Power Table 230VAC 15%± 85-265VAC Package Open Frame1 Open Frame1 CR6221T DIP-8L 9W 7W CR6224S SOP-8L 10W 8W CR6224T DIP-8L 15W 12W CR6228T DIP-8L 21W 18W CR6229T DIP-8L 28W 24W Notes: 1. Maximum practical continuous power in an open fram e design with sufficient drain pattern as a heat sink, at 50℃ ambient.

CR622X Green-Power Current Mode PWM Power Switch Nov, 2009 V2.2 4/10

Electrical Characteristics

(Ta=25°C unless otherwise noted, VDD = 16V) Symbol Parameter Test Conditions Min Typ Max Unit Supply Voltage (VDD) Istartup VDD Start up Current VDD=14.1V , Measure Leakage current into VDD 3 20 uA I_VDD (Operation) Operation Current V FB=3V 2 mA UVLO(ON) VDD Under V oltage Lockout Enter 8.5 9 9.5 V UVLO(OFF) VDD Under V oltage Lockout Exit(Recovery) 14.2 14.8 16 V OVP(ON) Over voltage protection voltage CS=0V , FB=3V Ramp up VDD until gate clock is off 27.0 28.5 30.0 V VDD_Clamp VDD Zener clamp V oltage I DD=10mA 30 V Feedback Input Section(FB pin) VFB_Open V FB Open Loop V oltage 5.4 5.6 6.0 V IFB_Short FB pin short circuit current Short FB pin to GND and measure current 1.55 mA VTH_0D Zero Duty Cycle FB Threshold V oltage 0.8 V VTH_PL Power Limiting FB Threshold V oltage 3.7 V TD_PL Power Limiting Debounce Time 50 mS ZFB_IN Input Impedance 4 K Ω Current Sense Input(Sense Pin) Soft start time 4 ms T_blanking Leading edge blanking time 300 ns ZSENSE_IN Input Impedance 40 K Ω TD_OC Over Current Detection and Control Delay From Over Current Occurs till the Gate drive 120 nS

CR622X Green-Power Current Mode PWM Power Switch Nov, 2009 V2.2 5/10 output start to turn off VTH_OC Internal Current Limiting Threshold V oltage FB=3.3V 0.76 0.8 0.82 V Oscillator Fosc Normal Oscillation Frequency 45 50 55 KHz f_Temp△ Frequency Temperature Stability 5 % f_VDD△ Frequency V oltage Stability 5 % D_max Maximum duty cycle FB=3.3V , CS=0V 70 80 90 % F_Burst Burst Mode Base Frequency 22 KHz Power MOSFET Section BVdss MOSFET Drain Source Breakdown V oltage VGS=0V , IDS=250uA 620 650 V CR6221T 12 15 Ω CR6224S 5.0 5.8 Ω CR6224T 5.0 5.8 Ω CR6228T 3.0 3.6 Ω RDS(on) Static Drain to Source On Resistance VGS=10V , IDS=1A CR6229T 2.0 2.5 Ω Frequency Shuffling f_△ SOC Frequency Modulation range /Base frequency -4 4 %

CR622X Green-Power Current Mode PWM Power Switch Nov, 2009 V2.2 6/10 OPERATION DESCRIPTION The CR622X is a low power off-line SMPS Switcher optimized for off-line flyback converter applications in sub 24W power range. The burst mode control greatly reduces the standby power consumption and helps the design easily to meet the international power conservation requirements. Startup Current and Start up Control Startup current of CR622X 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 2 MΩ, 1/8 W startup resistor could be used together with a VDD capacitor to provide a fast startup and yet low power dissipation design solution. Operation current The Operation current of CR622X is low at 2 mA. Good efficient is achieved with CR622X low operating current together with the ‘Extended burst mode’ control features. Soft Start CR622X features an internal 4 ms 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. Every restart up is followed by a soft start. Frequency shuffling for EMI improvement The frequency shuffling (switching frequency modulation) is implemented in CR622X. 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. Extended Burst Mode Operation 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 transformer 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 drops below burst mode threshold level and device enters Burst Mode control. The Gate drive output switches only when VDD voltage drops below a preset level and FB input is active to output an on state to minimize the switching loss and reduce the standby power consumption to the greatest extend. The switching frequency control also eliminates the audio noise at any loading conditions. Oscillator Normal Operation The normal switching frequency of CR622X is internally fixed at 50 KHz. No external frequency setting components are required for PCB design simplification. Current Sensing and Leading Edge Blanking Cycle-by-Cycle current limiting is offered in CR622X current mode PWM control. The switch current is detected by sense resistor into the sense pin. An internal leading edge blank circuit chops off the sensed voltage

CR622X Green-Power Current Mode PWM Power Switch Nov, 2009 V2.2 7/10 spike at initial internal power MOSFET on 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 limiting comparator is disabled and cannot turn off the internal power MOSFET during the blanking period. The PWM duty cycle is determined by the current sense input voltage and the FB input voltage. Internal synchronized Slope Compensation 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. Drive The internal power MOSFET in CR622X 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. Protection Controls Good power supply system reliability is achieved with its rich protection features including Cycle-by-Cycle current limiting (OCP); Over load Protection (OLP); Under Voltage Lockout on VDD (UVLO); Over voltage protection (OVP) and VDD clamp function. The OCP is line voltage compensated to achieve constant output power limit over the universal input 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 drops below UVLO limit. VDD is supplied by transformer auxiliary winding output. When VDD ramp up to OVP threshold voltage (28.5V), the output of CR622X will be shut down , when VDD drops below UVLO(ON) limit and Switcher enters power on start-up sequence thereafter . when VDD higher than VDD clamp threshold voltage, the internal VDD clamp circuitry will clamp VDD to 30V, and the output of CR622X is shut down also.

CR622X Green-Power Current Mode PWM Power Switch Nov, 2009 V2.2 8/10 CHARACTERIZATION PLOTS The characteristic graphs are normalized at TA=25℃. UVLO(ON)(V) VS Temperature(C) 9.00 9.20 9.40 9.60 9.80 10.00 -40 -10 20 50 80 110 Temperature(C) UVLO(ON)(V) Temperature&UVLO(ON) Vth_OC(V) VS Duty(%) 0.7 0.8 0.9 1.0 1.1 10 15 30 45 60 80 Duty(%) Vth_OC(V) Vth_OC&Duty Istartup(uA) VS Temperature(C) 2.0 2.5 3.0 3.5 4.0 -40 -10 20 50 80 110 Temperature(C) Istartup(uA) Istartup&Temperature Fosc(KHz) VS Temperature(C) -40 -10 20 50 80 110 Temperature(C) Fosc(KHz) Fosc&Temperature UVLO(OFF)(V) VS Temperature(C) 15.3 15.4 15.5 15.6 15.7 15.8 15.9 -40 -10 20 50 80 110 Temperature(C) UVLO(OFF)(V) Temperature&UVLO(OFF)

CR622X Green-Power Current Mode PWM Power Switch Nov, 2009 V2.2 9/10 PACKAGE DEMENSIONS D I P - 8 L Dimensions Millimeters Inches Symbol A 5.334 0.210 A1 0.381 0.015 b 1.524 0.060 b1 0.457 0.018 E 7.620 0.300 e 2.540 0.100

CR622X Green-Power Current Mode PWM Power Switch Nov, 2009 V2.2 10/10 SOP-8L Dimensions DISCLAIMERS A 1.346 1.752 0.053 0.069 A1 0.101 0.254 0.004 0.010 b 0.406 0.016 c 0.203 0.008 D 4.648 4.978 0.183 0.196 E 3.810 3.987 0.150 0.157 F 0.381X45 ° 0.015X45 H 5.791 6.197 0.228 0.244 L 0.406 1.270 0.016 0.050 θ˚ 0° 8° 0° 8°