www.fairchildsemi.com KA3843AC SMPS Controller Features Description • • • • • • • The KA3843AC are fixed PWM controller for Off-Line and DC to DC converter applications. The internal circuits include UVLO, low start up current circuit, temperature compensated reference, high gain error amplifier, current sensing comparator, and high current totem-pole output for driving a POWER MOSFET. Also KA3843AC provide low start up current below 0.3mA and short shutdown delay time typ. 100ns. The KA3843AC is 8.4V(on) and 7.6V(off). The KA3843AC can operate within 100% duty cycle. Low start current 0.2mA (typ) Operating range up to 500kHz Cycle by cycle current limiting Under voltage lock out with hysteresis Short shutdown delay time: typ.100ns High current totem-pole output Output swing limiting: 22V 8-DIP 1 8-SOP 1 Internal Block Diagram 7 VCC 29V 5V VREF VREF 8 SET/ RESET 5 GND UVLO Internal Bias Good LOGIC 7 1/2VREF VFB 2 Error Amp + - PWR VC C.S PWM Comp. LATCH 1/3 R 22V 1V 6 OUTPUT S COMP 1 5 PWR T C.S 3 RT/CT 4 GND OSCILLATOR Rev. 1.0.1 ©2005 Fairchild Semiconductor Corporation KA3843AC Absolute Maximum Ratings Parameter Symbol Value Unit Supply voltage VCC 30 V Output current IO +1 A VI(ANA) -0.3 to 6.3 V ISINK(EA) 10 mA PD 1 W Analog inputs (pin2, 3) Error amp. output sink current Power dissipation Electrical Characteristics (VCC = 15V, RT = 10KW, CT = 3.3nF, TA = 0°C to +70°C ,Unless otherwise specified) Parameter Symbol Conditions Min. Typ. Max. Unit REFERENCE SECTION Output voltage VREF TJ = 25°C, IO = 1mA 4.9 5.0 5.1 V Line regulation RLine VCC = 12V to 25V - 6 20 mV RLOAD ISC IO = 1mA to 20mA Ta = 25°C - 6 -100 25 -180 mV mA 47 52 57 kHz - 0.2 1.7 1 - % V TJ = 25°C 7.8 8.3 8.8 mA (Note2, 3) VPIN1 = 5V(Note2) 2.85 0.9 3 1.0 3.15 1.1 V/V V Load regulation Output short circuit OSILLATOR SECTION Initial accuracy FOSC TJ = 25°C Voltage stability Amplitude STV VOSC VCC = 12V to 25V VPIN4, peak to peak Discharge current IDISCHG CURRENT SENSE SECTION Gain Maximum input signal GV VI(MAX) PSRR PSRR VCC = 12V to 25V (Note1, 2) - 70 - dB Input bias current IBIAS VSENSE=0V - -2 -10 uA VPIN3 = 0 V to 2V (Note1) - 100 200 ns Delay to output TD Notes: 1. These parameters, although guaranteed, are not 100% tested in production. 2. Parameter measured at trip point of latch with VFB = 0V. ∆V COMP 3. Gain defined as: G V = ------------------------- ;O ≤ V SENSE ≤ 0.8V ∆V SENSE 2 KA3843AC Electrical Characteristics (Continued) (VCC = 15V, RT = 10KW, CT = 3.3nF, TA = 0°C to +70°C, Unless otherwise specified) Parameter Symbol Conditions Min. Typ. Max. Unit 2.42 2.50 2.58 V ERROR AMPLIFIER SECTION Input voltage VI VPIN1 = 2.5V Input bias current IBIAS VFB=0V - -0.3 -2 uA Open loop gain GVO VO = 2V to 4V (Note1) 65 90 - dB Unity gain bandwidth GBW TJ= 25°C (Note1) 0.7 1 - MHz PSRR PSRR VCC = 12V to 25V (Note1) 60 70 - dB Output sink current ISINK VPIN2 = 2.7V, VPIN1 = 1.1V 2 6 - mA ISOURCE VPIN2 = 2.3V, VPIN1 = 5.0V Output source current -0.5 -0.8 - mA 5 6 - V Output high voltage VOH VPIN2 = 2.3V R1 = 15KΩ to GND Output low voltage VOL VPIN2 = 2.7V R1 = 15kΩ to Vref - 0.7 1.1 V ISINK = 20mA - 0.1 0.4 V ISINK = 200mA - 1.5 2.2 V ISOURCE = 20mA 13 13.5 - V ISOURCE = 200mA 12 13.5 - V OUTPUT SECTION Output Low Level VOL Output high level VOH Rise time tR TJ = 25°C, C1 = 1nF (Note1) - 40 100 ns Fall time tF TJ = 25°C, C1 = 1nF (Note1) - 40 100 ns VCC = 27V, C1 = 1nF - 22 - V KA3882E 15 16 17 V KA3883E 7.8 8.4 9.0 V KA3882E 9 10 11 V KA3883E 7.0 7.6 8.2 V KA3882E/KA3883E 94 96 100 % Output voltage swing limit VOLIM UNDER VOLTAGE LOCKOUT SECTION Start threshold Min. operating voltage ( after turn on ) VTH VTL PWM SECTION Maximum duty cycle DMAX Minimum duty cycle DMIN - - - 0 % Start-up current IST - - 0.2 0.4 mA Operating supply current ICC VPIN2 = VPIN3 = 0V - 11 17 mA VCC zener voltage VZ ICC = 25mA - 29 - V TOTAL STANDBY CURRENT * Adjust VCC above the start threshold before setting at 15V Notes : 1. These parameters, although guaranteed, are not 100% tested in production. 2. Parameter measured at trip point of latch with VFB = 0V. ∆V COMP 3. Gain defined as: G V = ------------------------- ;O ≤ V SENSE ≤ 0.8V ∆V SENSE 3 KA3843AC Mechanical Dimensions Package Dimensions in millimeters 1.524 ±0.10 #5 2.54 0.100 5.08 MAX 0.200 7.62 0.300 3.40 ±0.20 0.134 ±0.008 +0.10 0.25 –0.05 +0.004 0~15° 4 0.010 –0.002 3.30 ±0.30 0.130 ±0.012 0.33 MIN 0.013 0.060 ±0.004 #4 0.018 ±0.004 #8 9.60 MAX 0.378 #1 9.20 ±0.20 0.362 ±0.008 ( 6.40 ±0.20 0.252 ±0.008 0.46 ±0.10 0.79 ) 0.031 8-DIP KA3843AC Mechanical Dimensions (Continued) Package Dimensions in millimeters 8-SOP 5 KA3843AC Ordering Information Product Number Package KA3843AC 8-DIP KA3843ACD 8-SOP Operating Temperature 0 ~ +70°C 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 CORPORATION. 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, and (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 a significant injury of the user. 2. A critical component in 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 3/2/05 0.0m 001 Stock#DSxxxxxxxx ” 2005 Fairchild Semiconductor Corporation