TECHNICAL DATA Fixed Frequency Current Mode PWM Controller IL3843 DESCRIPTION Fixed frequency current-mode PWM controller. It is specially designed for Off Line And DC-to-DC converter applications with minimal external component. This integrated circuit features a trimmed oscillator for precise duty cycle control. a temperature compensated reference, high gain arror amplifier, current sensing comparator, and a high current totempole output ideally suited for driving a power MOSFET. Protection circuitry includes built in under-voltage lockout and current limiting. FEATURES ORDERING INFORMATION IL3843N DIP IL3843D SOP TA = 0 to 70 C for all packages. Automatic Feed Forward Compensation High Gain Totem Pole Output Internally Trimmed Bandgap Reference Undervoltage Lockout with Hysteresis Low Start Up Current Optimized for offline converter Double pulse suppression Current mode operation to 500KHz ORDERING INFORMATION Device Operating Package Temperature Range IL3843N TA=0° to +70°C DIP-8 IL3843D TA=0° to +70°C SOP-8 2011, February, Rev. 03 IL3843 PIN FUNCTION DESCRIPTION Pin Function No. 1 Compensation Description This pln is the Error Amplifier output and is made available for loop compensation This is the inverting input of the Error Amplifier. It is normally connected to the switching power supply outpul through a resistor divider. A voltage proportional to inductor current is connected to this input. The PWM uses this. information to terminate the output switch conduction 2 Voltage Feedback 3 Current Sense 4 RT/CT The Oscillator frequency and maximum Output duty cycle are programmed by connecting resistor RT to VREF and capacitor CT to ground. Operation to 500kHz is possible. 5 GND 6 Output 7 Vcc This pin is the combined conlrol circuitry and power ground This output directly drives the gate of a power MOSFET. Peak currents up to 1,0A are sourced and sunk by this pin. This pin is the positive supply of the control IC. 8 VREF This is the reference output. It provides chsarging current for capacitor CT through resistor RT ABSOLUTE MAXIMUM RATINGS Characteristic Symbol Value Unit (ICC+ IZ) 30 mA Output Current IO 1.0 A Output Energy (Capacitive Load per Cycle) W 5.0 J Error Amp Output Sink Current IOE 10 mA Vin -0.3 to 5.5 V PD 0.862 0.625 W RθJA 145 °C/W TJ +150 o -65 ~ +150 o Total Power Supply and Zener Current Current Sense and Voltage Feedback Inputs o Maximum Power Dissipation @ TA= 25 C: DIP-8 SOP-8 Thermal Resistance,Junction-to-Air Operating Junction Temperature Storage Temperature Range Tstg C C * Stresses beyond those listed under “absolute maximum ratings” may cause permanent damage to the device. These are stress ratings only and functional operation of the device at these or any other conditions beyond those indicated under “recommended operating conditions” is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. 2011, February, Rev. 03 IL3843 ELECTRICAL CHARACTERISTICS (Vcc=15V unless otherwise noted) Characteristics REFERENCE SECTION Reference Output Voltage (IO=1.0mA, VCC=15V,TA=2510°C) (IO=1.0mA, VCC=15V,TA= Tlow to Thigh) Line Regulation (VCC=12V to 25V,TA=Tlow to Thigh) Load Regulation (IO=1.0 to 20mA,TA=Tlow to Thigh) Total Output Variation over Line,Load,Temperature (Note1) (VCC=12V, IO=1.0mA,TA=Tlow to Thigh) (VCC=25V, IO=20mA,TA=Tlow to Thigh) Output Short Circuit Current (VCC=15V) Symbol Min Max Unit Vref 4.9 4.865 5.1 5.135 V Regline 20 mV Regload 25 mV Vfinal 4.82 5.18 V ISC -30 -180 mA fosc 47 46 57 60 kHz 1.0 % 7.5 7.2 9.3 9.5 mA VFB IIB 2.42 2.58 -2.0 V A AVOL 65 dB BW 0.7 MHz PSRR 60 dB ISink ISource 2.0 -0.5 mA VOH VOL 5.0 Av 2.85 3.15 V/V Vth IIB 0.9 1.1 -10 V A 300 ns OSCILLATOR SECTION Frequency (VCC=15V,Tj=25°C,RT=10k,CT=3.3nF) (VCC=15V, TA=Tlow to Thigh,RT=10k,CT=3.3nF) Frequency Change with Voltage (VCC=12V to 25V, TA=Tlow to Thigh,RT=10k,CT=3.3nF) Discharge Current (Vosc=2.0V, VCC=15V) Tj=25°C TA=Tlow to Thigh Δfosc/ΔV Idisch ERROR AMPLIFIER SECTION Voltage Feedback Input (VO=2.5V,VCC=15V, TA=Tlow to Thigh) Input Bias Current (VFB=2.7V,VCC=15V, TA=Tlow to Thigh) Open Loop Voltage Gain (VO=2.0V to 4.0V,VCC=15V, TA=Tlow to Thigh) Unity Gain Bandwidth (VCC=15V, TA=Tlow to Thigh) Power Supply Rejection Ratio (VCC=12V to 25V, Vo=3.0V, TA=Tlow to Thigh) Output Current Sink (VO=1.1V,VFB=2.7V, VCC=15V, TA=Tlow to Thigh) Source (VO=5.0V,VFB=2.3V, VCC=15V, TA=Tlow to Thigh) Output Voltage Swing High State (VFB=2.3V, VCC=15V,RL(GND)=15k, TA=Tlow to Thigh) Low State (VFB=2.7V, VCC=15V,RL(5.0)=15k, TA=Tlow to Thigh) 1.1 V CURRENT SENSE SECTION Current Sense Input Voltage Gain (VFB=0V, VCC=15V, TA=Tlow to Thigh) Maximum Current Sense Input Threshold (VFB=0V, VCC=15V, TA=Tlow to Thigh) Input Bias Current (VCC=15V, TA=Tlow to Thigh) Propagation Delay (Current Sense Input to Output) (VCC=15V, TA=Tlow to Thigh) tPLH 2011, February, Rev. 03 IL3843 ELECTRICAL CHARACTERISTICS (Vcc=15V unless otherwise noted) Characteristics OUTPUT SECTION Output Voltage Low State (Sink=20mA, VCC=15V) (Sink=200mA, VCC=15V) High State (Sink=-20mA, VCC=15V) (Sink=-200mA, VCC=15V) Output Voltage with UVLO Activated (VCC=6.0V, ISink,=1.0mA, TA=Tlow to Thigh) Symbol Min Max Unit 0.4 2.2 V 1.1 V tr 150 ns tf 150 ns VOL VOH 13 12 VOL(UVL O) Output Voltage Rise Time (CL=1.0nF, VCC=15V, TA=Tlow to Thigh) Output Voltage Fall Time (CL=1.0nF, VCC=15V, TA=Tlow to Thigh) ONDERVOLTAGE LOCKOUT SECTION Startup Threshold (VCC=0V to 15V,TA=Tlow to Thigh) Minimum Operating Voltage After Turn-On (VCC=15V to 0V,TA=Tlow to Thigh) PWM SECTION Duty Cycle Maximum (VCC=15V, TA=Tlow to Thigh,RT=10k,CT=3.3nF) Minimum (VCC=15V, TA=Tlow to Thigh,RT=10k,CT=3.3nF) TOTAL DEVICE Power Supply Current Startup: VCC=6.5V VCC=15V Operating Power Supply Zener Voltage (ICC=25mA, VCC=0 to 40V) Vth 7.8 9.0 V VCC(min) 7.0 8.2 V DCmax DCmin 94 0 ICC Vz 30 1.0 17 40 % mA V NOTES: 1 Vfinal= Vref25 ( Regline+ Regload)/1000 | Vref70(Vref0)-Vref25 | Vref25=Vref @ TA=25°C; Vref70=Vref @ TA=70°C; Vref0 =Vref @ TA=0°C. 2. Tlow= 0°C ; Thigh=+70°C 2011, February, Rev. 03 IL3843 2011, February, Rev. 03