LT1248 Power Factor Controller FEATURES DESCRIPTIO n High Power Factor Over Wide Load Range The LT 1248 provides active power factor correction for with Line Current Averaging universal off-line power systems. By using fixed high n International Operation Without Switches frequency PWM current averaging, without the need for n Instantaneous Overvoltage Protection slope compensation, the LT1248 achieves far lower line n Minimal Line Current Dead Zone current distortion with a smaller magnetic element than n Typical 250m A Start-Up Supply Current systems that use either peak-current detection or zero n Rejects Line Switching Noise current switching approaches in both continuous and n Synchronization Capability discontinuous modes of operation. n Low Quiescent Current: 9mA The LT1248 uses a multiplier containing a square gain n Fast 1.5A Peak Current Gate Driver function from the voltage amplifier to reduce the AC gain at light output load and thus maintains low line current U distortion and high system stability. The LT1248 also APPLICATIO S provides filtering capability to reject line switching noise n Universal Power Factor Corrected Power Supplies which can cause instability when fed into the multiplier. n Preregulators Up To 1500W Line current dead zone is minimized with low bias voltage at the current input to the multiplier. The LT1248 provides many protection features including peak current limiting and overvoltage protection, and can be operated at frequencies as high as 300kHz. , LTC and LT are registered trademarks of Linear Technology Corporation. BLOCK DIAGRA M I CA GND V VA V PK REF OUT SENSE OUT LIM CC OUT 9 4 7 5 32 1 15 7.5V + V V CC REF + 16V TO 10V RUN 2.6V/ EN/SYNC 2.2V 7m A 2.2V + + 10 M1 V SENSE 11 I A EA I 2 M CA I I + A B + I 32k I = AC M 2 7.5V I B 200m A R 6 R Q + + 7.9V OVP + S RUN 16 8 0.7V GTDR SYNC ONE SHOT OSC 200ns 12m A + 5V SS 13 1 6V 14 12 1248 BD C R SET SET 1 W ULT1248 PACKAGE/ORDER I FOR ATIO ABSOLUTEXAI U RATI GS (Note 1) Supply Voltage ....................................................... 27V ORDER PART TOP VIEW NUMBER GTDR Current Continuous ..................................... 0.5A GND 1 16 GTDR GTDR Output Energy(Per Cycle) .............................. 5m J PK 2 15 V CC LIM I , R , PK Input Current............................. 20mA AC SET LIM CA 3 14 C SET OUT LT1248CN V , EN/SYNC, OVP Input Voltage................... V SENSE MAX I 4 13 SS SENSE LT1248IN I , M Input Current .................................. 5mA M 5 12 R SENSE OUT SET OUT LT1248CS Operating Junction Temperature Range I 6 11 V SENSE AC LT1248IS VA 7 10 EN/SYNC LT1248C ................................................ 0 C to 100 C OUT OVP 8 9 V REF LT1248I ........................................... 40 C to 125 C Thermal Resistance (Junction-to-Ambient) N PACKAGE 16-LEAD PDIP N Package .................................................. 100 C/W S PACKAGE 16-LEAD NARROW PLASTIC SO S Package................................................... 120 C/W T = 125 C, q = 100 C/W (N) JMAX JA Storage Temperature Range ..................65 C to 150 C T = 125 C, q = 120 C/W (S) JMAX JA Lead Temperature (Soldering, 10 sec)................. 300 C Consult factory for Military grade parts. ELECTRICAL CHARACTERISTICS The l denotes specifications which apply over the full operating tempera- ture range, otherwise specifications are at T = 25 C. Maximum operating voltage (V ) = 25V, V = 18V, R = 15k to GND, A MAX CC SET C = 1nF to GND, I = 100m A, I = 0V, CA = 3.5V, VA = 5V, OVP = 7.5V, no load on any outputs, unless otherwise noted. SET AC SENSE OUT OUT PARAMETER CONDITIONS MIN TYP MAX UNITS Overall Supply Current (V in Undervoltage Lockout) V = Lockout Voltage 0.2V l 0.25 0.45 mA CC CC Supply Current (Inactive) EN/SYNC = 0V, V V l 0.5 1.5 mA CC MAX Supply Current, On 11.5V V V , CA = 1V l 8.5 12.0 mA CC MAX OUT V Turn-On Threshold (Undervoltage Lockout) l 15.5 16.5 17.5 V CC V Turn-Off Threshold l 9.5 10.5 11.5 V CC EN/SYNC Threshold, Rising l 2.2 2.6 2.85 V EN/SYNC Threshold Hysteresis 0.40 V EN/SYNC Input Current EN/SYNC = 0V l 5 1 5 m A 3V EN/SYNC 7V 50 25 50 m A Voltage Amplifier Voltage Amp Offset Voltage VA = 3.5V l 8 8 mV OUT Input Bias Current V = 0V to 7V l 25 250 nA SENSE Voltage Gain 70 100 dB Voltage Amp Unity-Gain Bandwidth 3 MHz Voltage Amp Output High (Internally Clamped) l 11.3 13.3 V Voltage Amp Output Low l 1.1 2 V Voltage Amp Short-Circuit Current VA = 0V l 514 30 mA OUT SS Current SS = 2.5V l 512 30 m A Current Amplifier Current Amp Offset Voltage l 1 4mV I Bias Current l 25 250 nA SENSE Current Amp Voltage Gain 80 110 dB Current Amp Unity-Gain Bandwidth 3 MHz Current Amp Output High l 7.2 8.5 V Current Amp Output Low l 1.1 2 V 2 U WU U W W W