CM3842/3843 CURRENT MODE PWM CONTROLLER GENERAL DESCRIPTION FEATURES The CM3842/43 are fixed frequency current-mode PWM ! Low Start-Up current ( typ. 200µA) controllers specially designed for OFF-Line switching ! Optimized for Off-Line and DC-to-DC Converters power supply and DC-to-DC converters with a minimum ! Maximum Duty Cycle number of external components. These devices feature ! U.V.L.O. with Hysteresis a trimmed oscillator for precise duty cycle control, a ! Operating Frequency Up to 500KHz temperature compensated reference, high gain error ! Internal Trimmed Bandgap Reference amplifier, current sensing comparator, and high current ! High Current Totem Pole Output totem pole output which is suitable for driving ! ! MOSFETs. The under voltage lock-out (U.V.L.O.) is designed to Error Amplifier With Low Output Resistance Available in 8-Pin Plastic DIP and Surface Mount 8-Pin S.O.I.C. operated with 200µA typ. start-up current, allowing an efficient bootstrap supply voltage design. The U.V.L.O. thresholds for the CM3842 are 16V (on) and 10V (off) which are ideal for off-line applications. The corresponding typical threshold for the CM3843 are 8.4V (on) and 7.6V (off). The CM3842/43 can operated within 100% duty cycle. PIN CONFIGURATION APPLICATIONS ! Off-line flyback or forward converters. ! DC-to-DC buck or boost converter. ! Monitor Power Supply VREF COMP VCC VFB ISENSE OUTPUT RT/CT GND 8-Pin PDIP (Top View) AVAILABLE OPTIONS Device CM3842 Start-UP Voltage Hysteresis Max. Duty Cycle 16V 6V < 100% COMP VFB ISENSE RT/CT CM3843 8.4V 0.8V VREF VCC OUTPUT GND < 100% 8-Pin S.O.I.C. (Top View) 2001/06/27 Advanced Champion Microelectronic Corporation Page 1 CM3842/3843 CURRENT MODE PWM CONTROLLER ORDERING INFORMATION Part Number Temperature Range Package CM3842/43CP 0℃ to 70℃ 8-Pin PDIP(P08) CM3842/43CS 0℃ to 70℃ 8-Pin SOIC(S08) BLOCK DIAGRAM 7 Internal Bias 36V U.V.L.O. VREF 5V EN VREF 8 VCC 5 GND VREF Good Logic 7 Error Amp VFB Current Sense C 2R 2 R 1V PWM Latch R COMP 1 PWR VC OUTPUT 6 S CURRENT SENSE RT/CT 3 4 T PWR 5 GND Oscillator Note 1 :VCC and PWR VC are internally connected for 8 pin packages. Note 2 :PWR GND and GND are internally connected for 8 pin packages. Note 3 :U.V.L.O. is 16V for 3842 and 8.4V for 3843. Note 4 :Hysteresis is 6V for 3842 and 0.8V for 3843. 2001/06/27 Advanced Champion Microelectronic Corporation Page 2 CM3842/3843 CURRENT MODE PWM CONTROLLER ABSOLUTE MAXIMUM RATINGS Supply voltage, VCC 35V Output current, IO ± 1A Analog inputs, VI -0.3V to 6.3V Error amp output sink current, ISINK(EA) 10mA O Power dissipation (TA = 25 C), PD 1W Maximum junction temperature TJ 150 C Storage temperature range -65OC to 150OC Lead temperature (soldiering, 10 seconds) 260 C Note 5: O O Exceeding these ratings could cause damage to the device. All voltages are with respect to Ground. Currents are positive into, negative out of the specified terminal. THERMAL DATA PDIP PACKAGE: Thermal Resistance-Junction to Ambient, θJA 95 OC/W SOIC PACKAGE: Thermal Resistance-Junction to Ambient, θJA Junction Temperature Calculation: O 165 C/W TJ = TA + (PD × θJA). The θJA numbers are guidelines for the thermal performance of the device/pc-board system. All of the above assume no ambient airflow. 2001/06/27 Advanced Champion Microelectronic Corporation Page 3 CM3842/3843 CURRENT MODE PWM CONTROLLER RECOMMENDED OPERATING CONDITIONS Parameter Symbol Recommended Operating Min. Supply Voltage Typ. Max. VCC / VC VI,RT/CT Input Voltage Units 30 V 0 5.5 V 0 30 V VI,ISENSE/VFB Output Voltage VO, Output Supply Current ICC 25 mA Average Output Current IO 200 mA IO(REF) -20 mA Reference Output Current Timing Capacitor CT Oscillator Frequency fOSC Operating Free-air Temperature TA 1 nF 100 500 0 KHz O 70 C ELECTRICAL CHARACTERISTICS Unless otherwise specified, these specifications apply over the operating ambient temperature for CM384X with 0 C ≤ O TA ≤70 C; VCC = 15V(note 7); RT = 10K;CT = 3.3nF. Low duty cycle pulse testing techniques are used which O maintains junction and case temperatures equal to the ambient temperature. CM384X Parameter Symbol Test Conditions Units Min. Typ. Max. 4.9 5.0 5.1 V 6 20 mV 6 25 mV -100 -180 mA Reference Section Reference output Voltage O VREF TJ = 25 C, IREF = 1mA 12V ≤ VCC ≤ 25V,TJ = 25 C O Line Regulation 1mA ≤ IREF ≤ 20mA Load Regulation Short Ciruit Output Current O -30 O 47 ISC TJ = 25 C f TJ = 25 C Oscillator Section Oscillation Frequency 52 57 KHz Frequency Change with Voltage 12V ≤ VCC ≤ 25V 0.2 1.0 % Frequency Change with Temperature TMIN ≤ TA ≤ TMAX 5 % 1.7 V (note 8) Peak-to-peak Amplitude At RT/CT VOSC Current Sense Section Gain (note 9 & 10) AVOL Maximum Input Signal (note 9) VI(MAX) COMP = 5V Power Supply Rejection Ratio (note 9) PSRR 12V ≤ VCC ≤ 25V (note 9) Input Bias Current 2001/06/27 Advanced 2.85 3.00 3.15 0.9 1.0 1.1 IBIAS 70 -3.0 Champion Microelectronic Corporation V/V V dB -10 µA Page 4 CM3842/3843 CURRENT MODE PWM CONTROLLER ELECTRICAL CHARACTERISTICS (Continued) Error Amplifier Section Input Bias Current IBIAS Input Voltage VI(EA) COMP = 2.5V GVO 2V ≤ VO ≤ 4V Open Loop Voltage Gain -0.1 -2 µA 2.42 2.50 2.58 V 65 90 dB Unity Gain Bandwidth (note 8) UGBW TJ = 25 C 0.7 1 MHz Power Supply Rejection Ratio PSRR 12V ≤ VCC ≤ 25V 60 70 dB ISINK VFB = 2.7V, COMP = 1.1V 2 7 mA ISOURCE VFB = 2.3V, COMP = 5.0V -0.5 -1.0 mA 5 6 V Output Sink Current Output Source Current O High Output Voltage VOH VFB = 2.3V, RL = 15KΩ to GND Low Output Voltage VOL VFB = 2.7V, RL = 15KΩ to VREF 0.7 1.1 ISINK = 20mA 0.1 0.4 ISINK = 200mA 1.4 2.2 V Output Section Output Low Level Output High Level VOL VOH ISOURCE = 20mA 13 13.5 ISOURCE = 200mA 12 13.0 V V O 50 150 ns O 50 150 ns Rise Time (note 8) tr TJ = 25 C, CL = 1nF Fall Time (note 8) tf TJ = 25 C, CL = 1nF Under-Voltage Lockout Section Start Threshold VTH(ST) Min. Operating Voltage CM3842 14.5 16.0 17.5 CM3843 7.8 8.4 9.0 CM3842 8.5 10 11.5 CM3843 7.0 7.6 8.2 CM3842/43 94 97 100 V V PWM Section Maximum Duty Cycle Minimum Duty Cycle 0 % % Total Standby Current Startup Current CM3842 0.2 0.35 CM3843 0.5 1.0 14 17 Operating Supply Current ICC VFB = ISENSE = 0V Zener Voltage VZ ICC = 25mA 30 35 note 7: Adjust VCC above the start threshold before setting at 15V note 8: These parameters, although guaranteed, are not 100% tested in production prior to shipment note 9: Parameters are measured at trip point of latch with VFB = 2V mA mA V note 10: Gain is measured between ISENSE and COMP with the input changing from 0V to 0.8V 2001/06/27 Advanced Champion Microelectronic Corporation Page 5 CM3842/3843 CURRENT MODE PWM CONTROLLER APPLICATION INFORMATION Error Amp 2R R 1V COMP Rf RS ISENSE Cf Current Sense Comparator GND Fig. 1. Current Sense Circuit Peak current (IS) is set by: IS(MAX) = 1V/RS VREF 2.5V Error Amp 0.5mA RT RT/CT VFB Zi CT Zf GND COMP Fig. 3. Oscillator Section 1.72 For RT < 5K, f = RTCT Fig. 2. Error Amplifier Configuration - the amplifier can source or sink up to 0.5mA VREF RT 4.7K VCC 2N2222 100K 1K Error AMP Adjust 4.7K 5K ISENSE Adjust COMP VREF VFB VCC 0.1µ µF 1K, 1W Output ISENSE Output RT/CT GND 0.1µ µF GND CT Fig. 4. Open-loop laboratory test fixture: Careful grounding techniques are necessary for high peak currents associated with capacitive loads. Timing and bypass capacitors should be connected to GND pin in a single point ground. The transistor and 5K potentiometer are used to sample the oscillator waveform and apply an adjustable ramp to the ISENSE pin 2001/06/27 Advanced Champion Microelectronic Corporation Page 6 CM3842/3843 CURRENT MODE PWM CONTROLLER APPLICATION INFORMATION (continued) 1K COMP VREF Shutdown 330Ω Ω ISENSE Shutdown 500Ω Ω To Current Sense Resistor Fig. 5. Shutdown Techniques - there are two ways to shutdown the PWM controller: 1) raise the voltage at ISENSE above 1V or, 2) pull the COMP below a voltage two diodes above ground. VREF 0.1µ µF RT RT/CT CT ISENSE R2 R1 ISENSE RSENSE C Fig 6. Slop Compensation – To achieve duty cycles over 50% for some applications , the above slope compensation technique is suggested by resistively summing a fraction of the oscillator ramp with the current sense signal. 2001/06/27 Advanced Champion Microelectronic Corporation Page 7 CM3842/3843 CURRENT MODE PWM CONTROLLER TYPICAL CHARACTERISTICS f-oscillator frequency and frequency variation Oscillator Frequency and Frequemcy Variation 1,000,000 100,000 1uF 0.1uF 0.01uF 0.001uF 10,000 1,000 100 10 1 10 100 1000 RT-Timing Resistance (unit: k ohm) 2001/06/27 Advanced Champion Microelectronic Corporation Page 8 CM3842/3843 CURRENT MODE PWM CONTROLLER 8-PIN PLASTIC DIP 5 8 INCHES MILLIMETERS B MIN 1 TYP MAX MIN TYP MAX A 0.355 0.365 0.400 9.02 9.27 10.16 B 0.240 0.250 0.280 6.10 6.35 7.11 4 A L F C G - - 0.210 - - 5.33 D - 0.018 - - 0.46 - F - 0.060 - - 1.52 - G - 0.100 - - 2.54 - H 0.050 - 0.090 1.27 - 2.29 J 0.008 - 0.015 0.20 - 0.38 K 0.115 0.130 0.150 2.92 3.30 3.81 L 0.300 BSC. J K H C M D M - 7º 7.62 BSC. 15º - 7º 15º 8-PIN PLASTIC S.O.I.C . INCHES MIN TYP MAX MIN TYP MAX A 0.183 - 0.202 4.65 - 5.13 B 0.144 - 0.163 3.66 - 4.14 C 0.068 - 0.074 1.73 - 1.88 D 0.010 - 0.020 0.25 - 0.51 F - 0.035 0.38 - 0.89 A B P F D G C SEATING PLAN K 2001/06/27 Advanced M J 0.015 G L MILLIMETERS 0.050 BSC 0.050 BSC J 0.007 - 0.010 0.19 - 0.25 K 0.005 - 0.010 0.13 - 0.25 L 0.189 - 0.205 4.80 - 5.21 M - - 8º - - 8º P 0.228 - 0.244 5.79 - 6.20 Champion Microelectronic Corporation Page 9 CM3842/3843 CURRENT MODE PWM CONTROLLER 8-PIN PLASTIC S.O.I.C. CARRIER DIMENSIONS D T2 MILLIMETERS C A 330 ± 1 DD 1.55 ± 0.1 B 100 ± 1 D1 1.5 ± 0.25 Po 4.0 ± 0.1 B A +0.5 C 13.0 -1.0 T1 DD E Po F D1 P Ao 2001/06/27 Advanced 2.2 ± 1 P1 2.0 ± 0.1 T1 12.5 ± 0.5 Ao 6.4 ± 0.1 T2 2.0 ± 0.2 Bo 5.2 ± 0.1 Ko 2.1 ± 0.1 t 0.30 ± 0.013 Wc P1 Wc D t Wt Wt 9.3 TYP. P 8.0 ± 0.1 E 1.75 ± 0.1 F 5.5 ± 0.1 Bo Ko 12.0 +0.3 -0.1 Champion Microelectronic Corporation Page 10 CERAMIC/SURGE ABSORBER SHANGHAI,CHINA DIODES LAB HANGZHOU,CHINA CERAMIC/PZT SHINCHU,TAIWAN DC POWER LAB TAIPEI,TAIWAN