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CR6842 Dataheets PDF



Part Number CR6842
Manufacturers Chip Rail
Logo Chip Rail
Description Green Power PWM Controller
Datasheet CR6842 DatasheetCR6842 Datasheet (PDF)

CR6842 Green-Power PWM Controller with Freq. Jittering Features z z z www.DataSheet4U.com z z z z z z z z Low Cost, Green-Power Burst-Mode PWM Very Low Start-up Current ( about 7.5µA) Low Operating Current ( about 3.0mA) Current Mode Operation Under Voltage Lockout (UVLO) VDD Over Voltage Protection(OVP) programmable over-temperature protection Internal Latch Circuit(OTP,OVP) Built-in soft start with 1ms Built-in Frequency jitter for better EMI Signature Soft Clamped gate output voltage 16.5V z .

  CR6842   CR6842



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CR6842 Green-Power PWM Controller with Freq. Jittering Features z z z www.DataSheet4U.com z z z z z z z z Low Cost, Green-Power Burst-Mode PWM Very Low Start-up Current ( about 7.5µA) Low Operating Current ( about 3.0mA) Current Mode Operation Under Voltage Lockout (UVLO) VDD Over Voltage Protection(OVP) programmable over-temperature protection Internal Latch Circuit(OTP,OVP) Built-in soft start with 1ms Built-in Frequency jitter for better EMI Signature Soft Clamped gate output voltage 16.5V z z z z z z z z z z VDD over voltage protect 25.5V Cycle-by-cycle current limiting Sense Fault Protection Output SCP (Short circuit Protection) Built-in Synchronized Slope Compensation Leading-edge blanking on Sense input Programmable PWM Frequency High-Voltage CMOS Process with ESD DIP-8 & SOP-8 Pb-Free Package Compatible with SG6842J&LD7552&OB2269 Applications z z Power Adaptor Battery Charger Adapter z z Open Frame Switching Power Supply LCD Monitor General Description The CR6842 is a low startup current , low cost, current mode PWM controller with Green-Power & burst-mode power-saving operation. The integrated functions such as the leading-edge blanking of the current sensing, internal slope compensation provide the users a high efficiency, low external component counts, and low cost solution for AC/DC power applications. The special Green-Power function provides off-time modulation to linearly decrease the switching frequency under light-load conditions. And under zero-load conditions, the power supply enters burst-mode to further reduce power consumption by shutting off PWM output. When the output of power supply is short or over loaded, the FB voltage will increase ,and if the FB voltage is higher than 5.2V for longer than 56msec the PWM output will be turned off. A external NTC resistor connected from pin RT to ground can be applied to over-temperature protection. Pulse by pulse current limit ensures a constant output current even under short circuit. PWM output will be disabled as long as VDD exceeds a threshold. When internal latch circuit is used to latch-off the controller, the latch will be reset when the power supply VDD is disabled. Dec.2006 V 1.3 1 Chengdu Chip-Rail Tech.Co.,Ltd CR6842 Pin Assignment & Description 1 2 3 4 www.DataSheet4U.com GND FB VIN RI GATE VDD SENSE RT 8 7 6 5 Name GND FB VIN RI RT SENSE VDD GATE Description GND Pin Voltage feedback pin. The PWM duty cycle is determined by FB and Sense. This pin is pulled high to the rectified line input through a large resistor for start-up. This pin is also used to detect line voltage to compensate for constant output power limit for universal AC input. By connecting a resistor to ground to set the switching freq.. Increasing the resistor will reduce the switching freq.. An NTC resistor is connected from this pin to ground for over-temperature protection. Current sense pin, The sensed voltage is used for current-mode control and pulse-by-pulse current limiting. Power supply voltage pin. Gate drive output to drive the external MOSFET.A soft driving waveform is implemented to improve EMI. Typical Application Circuit From bridge rectifier From auxiliary winding 1 2 3 4 GND FB VIN RI GATE VDD SENSE RT 8 7 6 Rs 5 NTC Dec.2006 V 1.3 2 Chengdu Chip-Rail Tech.Co.,Ltd CR6842 Block Diagram RI VIN 0.9V Current Reference VDD Soft Driver GATE www.DataSheet4U.com RT OTP PWM LATCH Internal BIAS OSC S R Blanking Circuit SENSE Slope Compensation VDD UVLO OVP Burst Mode Controller Green Mode Controller 56ms Debounce FB 5.2V GND Absolute Maximum Ratings Symbol VDD VFB VSense PD Parameter Supply voltage Pin Voltage Input Voltage to FB Pin Input Voltage to SENSE Pin Power Dissipation ESD Capability, HBM Model ESD Capability, Machine Model TL TSTG Lead Temperature(Soldering) Storage Temperature Range Rating 40 -0.3 to 6V -0.3 to 6V 1000 2000 200 DIP-8£¨ 10sec£© SOP-8£¨ 10sec£© 260 230 Unit V V V mW V V ¡æ ¡æ ¡æ -55 to + 150 Dec.2006 V 1.3 3 Chengdu Chip-Rail Tech.Co.,Ltd CR6842 Electrical Characteristics (Ta=27°C unless otherwise noted, VDD = 15V.) Symbol Parameter Supply Voltage (VDD Pin) IST Startup Current ISS VTH(ON) VTH(OFF) Operating Current Conditions VDD=17 VFB= VSENSE = 0V VDD=15 --- Min. Typ. 7.5 3.0 Max. 30 5 17.0 11.2 25.0 13.0 Unit µA mA V V V V Start Threshold Voltage Min. Operating Voltage VDD Over Voltage www.DataSheet4U.com VDD-OVP Protection(Latch off) VDD Low-Threshold Voltage VDD-th-g to Exit Green-OFF Mode Voltage Feedback (FB Pin) IFB Short Circuit Current VFB Open Loop Voltage Current Sensing (SEN Pin) Threshold voltage for current VTH limit TPD Delay to Output ZCS Input Impedance Bnk Leading Edge Blanking Time Oscillator (RI Pin) FOSC Frequency in nominal mode FOSC-green Frequency in green mode Beginning of frequency VN reducing at FB Voltage End of frequency reducing at VG FB voltage Frequency Temp. Stability 16.0 10.4 23.0 11.0 16.5 10.8 24.5 12.0 VFB=0V VFB=Open 1.42 6.00 mA V IVIN =.


DM13C CR6842 AN2356


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