TK75003 Datasheet | TOKO

PWM CONTROLLER Features s Power Factor Correction/Line Harmonics Reduction to Meet IEC1000-3-2 Requirements s Optimized for Off-Line Operation s Maximum Duty Ratio 88% (typ.) s Frequency Reduction for Improved Overcurrent Protection s Low Standby Current for Current-Fed Start-Up s Current-Mode or Voltage-Mode Control s Internal User-Adjustable Slope pensation s Functionally Integrated & Simplified 5-Pin Design APPLICATIONS s s s s s Power Factor Correction Converters Off-Line Power Supplies Industrial Power Supplies Tele Power Supplies Off-Line Battery Chargers DESCRIPTION The TK75003 is a simple primary side controller optimized for off-line switching power supplies including power factor correctors. It is suitable for both voltage-mode and currentmode control and has advanced Features not available in controllers with a higher pin count. The key to full functionality in a 5-pin design is that the current signal and the error signal are added together and fed into the feedback pin. A sawtooth current flowing out of the feedback pin provides a slope pensation ramp (in current-mode applications) or a PWM ramp (in voltage-mode applications), in proportion to the resistance terminating that pin. If the sum of the current sense signal, error signal and ramp signal exceeds the Overcurrent Detector threshold indicating that the Current Control Detector has lost control of the switch current, the charging current of the timing capacitor will be reduced to about 25% for the remainder of the clock period. The reduced charging current causes no more than a one-third reduction in switching frequency, effectively preventing short-circuit current runaway. TK75003 VCC NC NC 7500 3 GND CT Note: Pins 2 and 3 must be externally connected for proper operation. BLOCK DIAGRAM VCC ICT CT ICHG 205 µA OSCILLATOR IFR 146 µA IDS 2 m A f CLK BANDGAP REFERENCE 14.5 V 10.5 V 17.5 V UVLO ORDERING INFORMATION R FREQUENCY REDUCTION LATCH S TK75003D Tape/Ree...