KA3843B

www.fairchildsemi.com KA3842B/KA3843B/KA3844B/ KA3845B SMPS Controller Features Low Start up Current Maximum Duty Clamp UVLO With Hysteresis Operating Frequency up to 500KHz Description The KA3842B/KA3843B/KA3844B/KA3845B are fixed frequency current-mode PWM controller. They are specially designed for Off - Line and DC-to-DC converter applications with minimum external components. These integrated circuits feature a trimmed oscillator for precise duty cycle control, a temperature compensated reference, high gain error amplifier, current sensing comparator and a high current totempole output for driving a power MOSFET. The KA3842B and KA3844B have UVLO thresholds of 16V (on) and 10V (off). The KA3843B and KA3845B are 8.5V (on) and 7.9V (off). The KA3842B and KA3843B can operate within 100% duty cycle. The KA3844B and KA3845B can operate with 50% duty cycle. 8-DIP Internal Block Diagram 1 14-SOP 1 ©2002 Fairchild Semiconductor Corporation Rev. 1.0.2 KA3842B/KA3843B/KA3844B/KA3845B Absolute Maximum Ratings Parameter Symbol Value Supply Voltage Output Current Analog Inputs (Pin 2.3) Error Amp Output Sink Current Power Dissipation at TA≤25°C (8DIP) Power Dissipation at TA≤25°C (14SOP) Storage Temperature Range Lead Temperature (Soldering, 10sec) VCC IO V(ANA) ISINK (E.A) PD(Note1,2) PD(Note1,2) TSTG TLEAD 30 ±1 -0.3 to 6.3 10 1200 680 -65 ~ +150 +300 Note: 1. Board Thickness 1.6mm, Board Dimension 76.2mm ×114.3mm, (Reference EIA / JSED51-3, 51-7) 2. Do not e...