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TECHNICAL DATA
Fixed Frequency Current Mode PWM Controller
IL3842
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
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 IL3842 Operating Package Temperature Range TA=0 to +70C DIP-8
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IL3842
PIN FUNCTION DESCRIPTION
Pin Function No. 1 Compensation 2 3 4 5 6 7 8 Voltage Feedback Current Sense RT/CT GND Output Vcc VREF 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 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. 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. This is the reference output. It provides chsarging current for capacitor CT through resistor RT
ABSOLUTE MAXIMUM RATINGS
Characteristic Total Power Supply and Zener Current Output Current Output Energy (Capacitive Load per Cycle) Error Amp Output Sink Current Current Sense and Voltage Feedback Inputs Maximum Power Dissipation @ TA= 25 C: Thermal Resistance,Junction-to-Air Operating Junction Temperature Storage Temperature Range
o
Symbol (ICC+ IZ) IO W IOE Vin PD RJA TJ Tstg
Value 30 1.0 5.0 10 -0.3 to 5.5 0.862 145 +150 -65 ~ +150
Unit mA A J mA V W C/W o C
o
C
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IL3842
ELECTRICAL CHARACTERISTICS (Vcc=15V unless otherwise noted)
Characteristics REFERENCE SECTION Reference Output Voltage (IO=1.0mA, VCC=15V,TA=2510C) (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 Vref Regline Regload Vfinal ISC fosc fosc/V Idisch VFB IIB AVOL BW PSRR ISink ISource VOH VOL 7.5 7.2 2.42 65 0.7 60 2.0 -0.5 5.0 1.1 4.82 -30 47 46 Min 4.9 4.865 Max 5.1 5.135 20 25 5.18 -180 57 60 1.0 9.3 9.5 2.58 -2.0 Unit V mV mV V mA kHz % mA V A dB MHz dB mA V
OSCILLATOR SECTION
Frequency (VCC=15V,Tj=25C,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=25C TA=Tlow to Thigh
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, 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)
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) Av Vth IIB tPLH 2.85 0.9 3.15 1.1 -10 300 V/V V A ns
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IL3842
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) 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 25V,TA=Tlow to Thigh) Minimum Operating Voltage After Turn-On (VCC=0V to 25V,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=14V VCC=15V Operating Power Supply Zener Voltage (ICC=25mA, VCC=0 to 40V) Vth VCC(min) DCmax DCmin 14.5 8.5 94 0 1.0 17 40 17.5 11.5 V V Symbol VOL VOH VOL(UVL
O)
Min
Max
Unit
13 12
0.4 2.2
V
1.1 150 150
V ns ns
tr tf
%
ICC Vz 30
mA V
NOTES: 1. Vfinal= Vref25 ( Regline+ Regload)/1000 | Vref70(Vref0)-Vref25 | Vref70=Vref @ TA=70C; Vref0 =Vref @ TA=0C. Vref25=Vref @ TA=25C; 2. Tlow= 0C ; Thigh=+70C
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IL3842
N SUFFIX PLASTIC DIP (MS - 001BA)
A 8 5 B 1 4
Dimension, mm Symbol A B MIN 8.51 6.1 MAX 10.16 7.11 5.33 0.36 1.14 2.54 7.62 0 2.92 7.62 0.2 0.38 10 3.81 8.26 0.36 0.56 1.78
F
L
C D
C -T- SEATING N G D 0.25 (0.010) M T K
PLANE
F G
M H J
H J K L M N
NOTES: 1. Dimensions "A", "B" do not include mold flash or protrusions. Maximum mold flash or protrusions 0.25 mm (0.010) per side.
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