TK75001 Datasheet | TOKO

PWM CONTROLLER Features s s s s s s s s Optimized for Off-Line Operation Maximum Duty Ratio 44% (typ.) Maximum Clock Frequency Above 1 MHz Frequency Reduction for Improved Overcurrent Protection Low Standby Current for Current-Fed Start-Up Current-Mode or Voltage-Mode Control Internal User-Adjustable Slope pensation Functionally Integrated & Simplified 5-pin Design APPLICATIONS s s s s Off-Line Power Supplies Industrial Power Supplies Tele Power Supplies Off-Line Battery Chargers DESCRIPTION The TK75001 is a simplified primary side controller optimized for off-line switching power supplies. It is suitable for both voltage-mode and current-mode 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. VCC NC NC 7500 1 GND CT Note: Pins 2 and 3 must be externally connected for proper operation. BLOCK DIAGRAM VCC ICT BANDGAP REFERENCE 14.5 V 10.5 V OSCILLATOR IFR 146 µA IDS 2 m A f CLK 17.5 V UVLO ICHG 205 µA The TK75001 is available in an 8-pin DIP package. ORDERING INFORMATION R FREQUENCY REDUCTION LATCH S TOGGLE FF T Q TK75001D Tape/Reel Code Temperature Code SLOPE...