www.fairchildsemi.com FAN7554 Versatile PWM Controller Features * * * * * * * * * * * * * * * Current Mode Control Pulse by Pulse Current Limiting Low External Components Under Voltage Lockout(UVLO): 9V/15V Stand-by Current: Typ. 100uA Power Saving Mode Current: Typ. 200uA Operating Current: Typ. 7mA Soft Start On/Off Control Over Load Protection(OLP) Over Voltage Protection(OVP) Over Current Protection(OCP) Over Current Limit(OCL) Operating Frequency up to 500kHz 1A Totem-Pole Output Current Description The FAN7554 is a fixed frequency current mode PWM controller. It is specially designed for off-line and DC to DC converter applications with minimal external components. These integrated circuits feature a trimmed oscillator for precise duty cycle control, a temperature compensated reference, an ON/OFF control, a high gain error amplifier, a current sensing comparator, and a high current totem-pole output. The FAN7554 has various protection functions such as an over load protection, an over current protection, and the over voltage protection, which include built-in auto restart circuit. The FAN7554 is available in the 8-DIP package as well as the 8-SOP package. 8-DIP Applications * Off-Line & DC-DC Converter 8-SOP 1 1 Rev. 1.0.2 (c)2002 Fairchild Semiconductor Corporation FAN7554 Internal Block Diagram Rt/Ct 4 3.5V + _ S Q R off PWR / SAVE Vref 8 + + OVP Vcc 7 34V 1k + 0.3V 1.5V OSC CLK PWM + _ S Q R 14V FB 1 1mA Vref Vcc 5uA OLP OVP-out OCL-out + S R UVLO-out Q Absolute Maximum Ratings ( Ta = 25C, unless otherwise specified ) Parameter Supply Voltage Output Current Input Voltage to FB Pin Input Voltage to IS Pin Power Dissipation at TA 25C 8-DIP 8-SOP Operating Temperature Storage Temperature Thermal Resistance, Junction-to-Air (Note1) 8-DIP 8-SOP Note: 1. Junction -to -air thermal resistance test environments. -. Pneumatic heat sink fixture. -. Clamping pressure 60psi through 12mm diameter cylinder. -. Thermal grease applied between PKG and heat sink fixture Symbol Vcc IO VFB VIS PD TOPR TSTG Rja Value 30 1 -0.3 to VSD -0.3 to VOC 0.85 0.42 -25 to +85 -55 to +150 147.8 291.4 2 _ _ 6V + + _ S/S 2 on 15V/9V MAX. 1V 2R R Offset(0.1V) _ 100uA Vref + + Vref UVLO _ _ _ _ 6 OUT 3 OCL 2V IS 5 GND Unit V A V V W C C C/W FAN7554 Temperature Characteristics ( -25C Ta 85C ) Parameter Vref Temperature Stability Fosc Temperature Stability Symbol VREF3 FOSC2 Value 0.5 5 Unit % % PIN Array Vref Vcc OUT GND 8 7 6 5 YWW FA N7554 1 FB 2 S/S 3 IS 4 Rt/Ct PIN Definitions Pin Number 1 2 3 4 5 6 7 8 Pin Name FB S/S IS Rt/Ct GND OUT Vcc Vref Pin Function Description Inverting(-) Input of PWM Comparator, ON/OFF Control & OLP Sensing Terminal. Soft Start Non-Inverting(+) Input of PWM Comparator, OCL Sensing Terminal Oscillator Time Constant(Rt/Ct) Ground Output of Gate Driver Power Supply Output of 5V Reference 3 FAN7554 Electrical Characteristics (Ta = 25C, Vcc=16V, Rt=10k, Ct=3.3nF unless otherwise specified) Parameter < REFERENCE SECTION > Reference Output Voltage Line Regulation Load Regulation Short Circuit Output Current < OSCILLATOR SECTION > Oscillation Frequency Frequency Change with Vcc Ramp High Voltage Ramp Low Voltage Discharge Current < PWM SECTION > Sense Threshold Voltage Feedback Threshold Voltage Feedback Source Current Max. Duty Cycle Min. Duty Cycle < PROTECTION SECTION > Shutdown Delay Current Shutdown Feedback Voltage Over Current Protection Over Voltage Protection < ON/OFF CONTROL SECTION > Off Mode Sink Current Off Threshold Voltage < SOFT-START SECTION > Soft Start Current Soft Start Limit Voltage |