LT1508 Datasheet | Linear Technology

+ - + - W OBSOLETE: FOR INFORMATION PURPOSES ONLY Contact Linear Technology for Potential Replacement Features I PFC and PWM Single Chip Solution I Synchronized Operation up to 300k Hz I 99% Power Factor Over 20:1 Load Current Range I Voltage Mode PWM I Instantaneous Overvoltage Protection I Dedicated Overvoltage Protection (OVP Pin) I Minimal Line Current Dead Zone I Typical 250µA Start-Up Supply Current I Line Switching Noise Filter I Low Quiescent Current: 13m A I Fast 1.5A Peak Current Gate Drivers I Separate Soft Start Control U APPLICATIONS I Universal Power Factor Corrected Power Supplies and Preregulators Power Factor and PWM Controller (Voltage Mode) DESCRIPTION The LT ®1508 is a plete solution for universal off-line switching power supplies utilizing active power factor correction. The PFC section is identical to the LT1248 PFC controller except the EN/SYNC pin is removed because PFC and PWM are synchronized internally. The voltage mode PWM section (LT1509 is the current mode counterpart) contains all the primary side functions to convert the PFC preregulated high voltage output to an isolated low voltage output. The PWM duty cycle is internally limited to 47% (maximum 50%) to prevent transformer saturation. PWM soft start begins when the PFC output reaches the preset voltage. In the event of brief line loss, PWM will be shut off when the PFC output voltage drops below 73% of the preset value. , LTC and LT are registered trademarks of Linear Technology Corporation. BLOCK DIAGRAM VCC 16V TO 10V VSENSE 14 7.5V IAC 9 7.9V SS1 14µA + - - + + - 14µA SS2 13 PWMOK VAOUT 10 7.5V...