AN4129 FAIRCHILD | Alldatasheet

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switch to reduce the losses in the start-up circuit. under 1W input power when the input line voltage is 265V . On no load condition, input power is under 0.3W. IC operation when the supply voltage reaches 19V . It contains the following blocks.

  • Start-up circuit and reference
  • Oscillator
  • Soft start and latch
  • Current sense and feed back
  • Burst mode
  • Output drive Rev. 1.0.1 Latch/SS Delay Circuit Enable −−GND Start-up Circuit 2.5V 1.5V Start-up Circuit 5V Ref Vcc Vref Rt/Ct Latch/SS OUT CS/FB UVLO 12uA Vref 19V OVP + 12V/8V 0.97V/0.9V R QS OSC4 OVP R QS Reset Circuit+ Vstr

Figure 1. Internal Block Diagram of the FAN7601

chosen with reference to Fig. 5. Figure 5. Oscillator Frequency Characteristics when the Vcc voltage reaches the start threshold voltage. The soft start time Tss is calculated by (2). The latch protection is provided to protect the system. the Vcc voltage is lower than 5V . drops. Then the PNP transistor turns on and charges the Css. Figure 6. Thermal Protection Circuit the latch protection operates abnormally. Figure 7. Output Over Voltage Protection Circuit

  1. Current Sense and Feedback

voltage feedback and current sensing information. Figure 8 shows the current sensing and feedback circuits.

4 Css

Figure 11. DC Link Voltage and Current Waveforms and the diode RMS current can be calculated by (6). external power supplies under 75W. Table 1 shows the regulation target specification.

2 Vac_min⋅

must be lower than 0.45 to prevent subharmonic oscillation. Then the number of primary turns can be obtained as in (9). by (10). The calculated number of secondary turns is 10. The air gap length can be calculated by (11).

1 Dmax–

©2003 Fairchild Semiconductor Corporation Table 2: Experimental Results Input Power Output Power 85Vac 110Vac 220Vac 240Vac 265Vac 50W 59.2W 58W 57.8W 57.6W 57.8W

Figure 20. Application Circuit Diagram

4 R205

©2003 Fairchild Semiconductor Corporation Table 3: 50W Adapter Demo Board Part List PART# VALUE NOTE PART# VALUE NOTE FUSE CAPACITOR F101 250V 1A - C101 220nF/275V Box Cap. NTC C102 100nF/275V Box Cap. RT101 5D-9 - C103 150uF/400V Electrolytic R111 8k - C105 10pF Ceramic RESISTOR C106 272 Miler R101 - - C107 47uF/25V Electrolytic R103 56k 1/2W C108 103 Film R105 150 - C109 0.47uF Electrolytic R106 10k - C110, 111 102/1kV Ceramic R107 0.5 1/2W C112 104 Ceramic R108 1k - C201, 202 1000uF/25V Electrolytic R109 8k - C203 102 Ceramic R110 3.9k - C222 222/1kV Ceramic R112 1k - MOSFET R113 36k - Q101 FQPF7N60 Fairchild R114 1M - INDUCTOR R201 1.5k - LF101 23mH - R202 1.2k - L201 9uH - R203 0 - DIODE R204 27k - D101,102 UF4007 - R205 7k - D103 1N4148 - R206 10 1/2W D202, 204 MBRF20100CT - R207 10k - ZD201 15V Zener/1W - IC BD101 KBP206 - IC101 FAN7601 Fairchild TRANSISTOR IC201 KA431 Fairchild TR101 2N3906 Fairchild IC301, 302 H11A817B Fairchild

5/22/03 0.0m 002 Stock#ANxxxxxxxxx  2003 Fairchild Semiconductor Corporation DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. LIFE SUPPORT POLICY FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPROATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, or (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in significant injury to the user. 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. www.fairchildsemi.com 4. Transformer Specification Winding Specification Electrical Specification Core EER2828 Pin (S → F) Wire Turns Winding Method NP 1 → 20 . 3 5 φ × 22 7 NS 9 → 12 0.65 φ × 31 0 NP 2 → 30 . 3 5 φ × 22 7 NVCC 5 → 60 . 2 φ × 11 0 Pin Value Remarks Inductance 1 - 3 600uH 100kHz, 1V Leakage 1 - 3 15uH 2 nd shorted Np NVcc Ns NVcc Np Ns Np 3mm 3mm