AMC DOC. #: AMC3842B_A November 2001 AMC3842B/43B ADD MICROTECH CORP. CURRENT MODE PWM CONTROLLER DESCRIPTION FEATURES The AMC3842B/43B are fixed frequency current-mode PWM controllers specially designed for OFF-Line switching power supply and DC-to-DC converters with a minimum number of external components. These devices feature a trimmed oscillator for precise duty cycle control, a temperature compensated reference, high gain error amplifier, current sensing comparator, and high current totem pole output which is suitable for driving MOSFETs. The under voltage lock-out (U.V.L.O.) is designed to operated with 200A typ. start-up current, allowing an efficient bootstrap supply voltage design. The U.V.L.O. thresholds for the AMC3842B are 16V (on) and 10V (off) which are ideal for off-line applications. The corresponding typical threshold for the AMC3843B are 8.4V (on) and 7.6V (off). The AMC3842B/43B can operated within 100% duty cycle. ! ! ! ! # # # # # # APPLICATIONS PACKAGE PIN OUT COMP Off-line flyback or forward converters. DC-to-DC buck or boost converter. Monitor Power Supply ! ! ! AVAILABLE OPTIONS Start-UP Max. Duty Hysteresis Voltage Cycle Device Low Start-Up current ( typ. 200A) Optimized for Off-Line and DC-to-DC Converters Maximum Duty Cycle U.V.L.O. with Hysteresis Operating Frequency Up to 500KHz Internal Trimmed Bandgap Reference High Current Totem Pole Output Error Amplifier With Low Output Resistance Available in 8-Pin Plastic DIP and Surface Mount 14-Pin S.O.I.C. Identical pin assignment to earlier UC384X series. AMC3842B 16V 6V < 100% AMC3843B 8.4V 0.8V < 100% VFB VREF VCC ISENSE OUTPUT RT/CT GND 8-Pin Plastic DIP (Top View) VREF COMP NC VFB NC VCC VC NC ISENSE OUTPUT GND NC RT/CT PWR 14-Pin Plastic S.O.I.C. Surface Mount (Top View) VREF COMP VFB ISENSE VCC OUTPUT RT/CT GND 8-Pin Plastic S.O.I.C. Surface Mount (Top View) ORDER INFORMATION TA (OC) 0 to 70 Note: M Plastic DIP-8 8-pin AMC384XBM D Plastic SO-14 14-pin AMC384XBD All surface-mount packages are available in Tape & Reel. AMC384XBDT, or AMC384XBDMT). Copyright 2001, ADD Microtech Corp. 1 DM Plastic SO-8 8-pin AMC384XBDM Append the letter "T" to part number (i.e. www.addmtek.com AMC3842B/43B AMC DOC. #: AMC3842B_A CURRENT MODE PWM CONTROLLER November 2001 ABSOLUTE MAXIMUM RATINGS (Note 1) 35V Supply voltage, VCC Output current, IO 1A -0.3V to 6.3V Analog inputs, VI 10mA Error amp output sink current, ISINK(EA) 1W Power dissipation (TA = 25 OC), PD 150 OC Maximum juncture temperature, TJ Storage temperature range -65OC to 150OC Lead temperature (soldiering, 10 seconds) 260 OC Note 1: 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 M PACKAGE: Thermal Resistance-Junction to Ambient, JA D PACKAGE: Thermal Resistance-Junction to Ambient, JA DM PACKAGE: Thermal Resistance-Junction to Ambient, JA Junction Temperature Calculation: TJ = TA + (PD x JA). The JA numbers are guidelines for the thermal performance of the device/pc-board system. All of the above assume no ambient airflow. Copyright 2001, ADD Microtech Corp. 2 95 OC/W 120 OC/W 165 OC/W www.addmtek.com AMC3842B/43B AMC DOC. #: AMC3842B_A CURRENT MODE PWM CONTROLLER November 2001 BLOCK DIAGRAM 7 (12) Internal Bias VREF U.V.L.O. 36V 5V EN VREF 8 (14) VCC 5 (9) GND VREF Good Logic 7 (11) PWR Error Amp VFB VC Current Sense C 2R 2 (3) 1V R PWM Latch R COMP 1 (1) OUTPUT 6 (10) S CURRENT SENSE RT/CT 3 (5) 4 (7) T PWR 5 (8) GND Oscillator ( ) are 14 Pin S.O.I.C. pin number Note 2 Note 3 Note 4 Note 5 :VCC and PWR VC are internally connected for 8 pin packages. :PWR GND and GND are internally connected for 8 pin packages. :U.V.L.O. is 16V for 3842B and 8.4V for 3843B. :Hysteresis is 6V for 3842B and 0.8V for 3843B. Copyright 2001, ADD Microtech Corp. 3 www.addmtek.com AMC3842B/43B AMC DOC. #: AMC3842B_A CURRENT MODE PWM CONTROLLER November 2001 Supply Voltage Input Voltage Output Voltage RECOMMENDED OPERATING CONDITIONS Recommended Operating Conditions Parameter Symbol Min. Typ. Max. VCC / VC 30 VI,RT/CT 0 5.5 VI,ISENSE/VFB VO, Output 0 30 Units V V V 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 AMC384XB with 0OC TA 70 OC; VCC = 15V(note 6); RT = 10K;CT = 3.3nF. Low duty cycle pulse testing techniques are used which maintains junction and case temperatures equal to the ambient temperature. AMC384XB Parameter Symbol Test Conditions Units Min. Typ. Max. Reference Section Reference output Voltage VREF Line Regulation Load Regulation Short Ciruit Output Current ISC Oscillator Section Oscillation Frequency f Frequency Change with Voltage Frequency Change with Temperature (note 7) Peak-to-peak Amplitude At RT/CT VOSC Current Sense Section Gain (note 8 & 9) AVOL Maximum Input Signal (note 8) VI(MAX) Power Supply Rejection Ratio (note 8) PSRR Input Bias Current IBIAS Copyright 2001, ADD Microtech Corp. TJ = 25 OC, IREF = 1mA 12V VCC 25V,TJ = 25 OC 1mA IREF 20mA TJ = 25 OC 4.9 5.0 6 6 -100 5.1 20 25 -180 V mV mV mA 12V VCC 25V 52 0.2 1.0 KHz % TMIN TA TMAX 5 % 1.7 V -30 TJ = 25 OC COMP = 5V 12V VCC 25V (note 8) 4 2.85 0.9 3.00 1.0 70 -3.0 3.15 1.1 -10 V/V V dB A www.addmtek.com AMC3842B/43B AMC DOC. #: AMC3842B_A CURRENT MODE PWM CONTROLLER November 2001 ELECTRICAL CHARACTERISTICS (Continued) Error Amplifier Section Input Bias Current Input Voltage Open Loop Voltage Gain Unity Gain Bandwidth (note 7) Power Supply Rejection Ratio Output Sink Current Output Source Current High Output Voltage Low Output Voltage Output Section IBIAS VI(EA) GVO UGBW PSRR ISINK ISOURCE VOH VOL Output Low Level VOL Output High Level VOH Rise Time (note 7) Fall Time (note 7) Under-Voltage Lockout Section Start Threshold tr tf VTH(ST) Min. Operating Voltage COMP = 2.5V 2.42 65 2V VO 4V O TJ = 25 C 0.7 60 12V VCC 25V VFB = 2.7V, COMP = 1.1V 2 VFB = 2.3V, COMP = 5.0V -0.5 5 VFB = 2.3V, RL = 15K to GND VFB = 2.7V, RL = 15K to VREF -0.1 2.50 90 1 70 7 -1.0 6 0.7 -2 2.58 ISINK = 20mA ISINK = 200mA ISOURCE = 20mA ISOURCE = 200mA TJ = 25 OC, CL = 1nF TJ = 25 OC, CL = 1nF 0.1 1.4 13.5 13.0 50 50 0.4 2.2 150 150 14.5 7.8 8.5 7.0 16.0 8.4 10 7.6 17.5 9.0 11.5 8.2 94 97 100 0.35 1.0 17 30 0.2 0.5 14 35 AMC3842B AMC3843B AMC3842B AMC3843B 13 12 1.1 A V dB MHz dB mA mA V V V V ns ns V V PWM Section Maximum Duty Cycle Total Standby Current AMC3842B/43B Startup Current Operating Supply Current Zener Voltage note 6: note 7: note 8: note 9: ICC VZ AMC3842B AMC3843B VFB = ISENSE = 0V ICC = 25mA % mA mA V Adjust VCC above the start threshold before setting at 15V These parameters, although guaranteed, are not 100% tested in production prior to shipment Parameters are measured at trip point of latch with VFB = 2V Gain is measured between ISENSE and COMP with the input changing from 0V to 0.8V Copyright 2001, ADD Microtech Corp. 5 www.addmtek.com AMC3842B/43B AMC DOC. #: AMC3842B_A CURRENT MODE PWM CONTROLLER November 2001 Application Information Error Amp 2R R 1V Current Sense Comparator COMP Rf ISENSE RS Cf 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 Fig. 2. Error Amplifier Configuration - the For RT < 5K, f = amplifier can source or sink up to 0.5mA 1.72 RTCT VREF RT VCC 2N2222 4.7K 100K 1K Error AMP Adjust 5K 4.7K ISENSE Adjust COMP VREF VFB VCC 0.1 F 1K, 1W Output ISENSE Output RT/CT GND 0.1 F 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 Copyright 2001, ADD Microtech Corp. 6 www.addmtek.com AMC3842B/43B AMC DOC. #: AMC3842B_A CURRENT MODE PWM CONTROLLER November 2001 Application Information (continued) 1K COMP VREF Shutdown 330 ISENSE Shutdown 500 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 0.1 F 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. Copyright 2001, ADD Microtech Corp. 7 www.addmtek.com AMC3842B/43B AMC DOC. #: AMC3842B_A CURRENT MODE PWM CONTROLLER November 2001 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 - 7 7.62 BSC. 15 - 7 15 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 Copyright 2001, ADD Microtech Corp. 0.015 G L M J 8 MILLIMETERS 0.050 BSC 1.27 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 - - 8 - - 8 P 0.228 - 0.244 5.79 - 6.20 www.addmtek.com AMC3842B/43B AMC DOC. #: AMC3842B_A CURRENT MODE PWM CONTROLLER November 2001 14-Pin Plastic S.O.I.C. INCHES MILLIMETERS MIN TYP MAX MIN TYP MAX A 0.336 - 0.344 8.54 - 8.74 B 0.159 - 0.158 3.81 - 4.01 C 0.053 - 0.069 1.35 - 1.75 D 0.014 - 0.018 0.35 - 0.46 F - 0.030 0.67 - 0.77 A B P F G D G L C SEATING PLAN K Copyright 2001, ADD Microtech Corp. 0.026 M J 9 0.050 BSC 1.27 BSC J 0.007 - 0.010 0.19 - 0.25 K 0.004 - 0.010 0.10 - 0.25 L 0.189 - 0.205 4.82 - 5.21 M - - 8 - - 8 P 0.228 - 0.244 5.79 - 6.20 www.addmtek.com AMC3842B/43B AMC DOC. #: AMC3842B_A CURRENT MODE PWM CONTROLLER November 2001 IMPORTANT NOTICE ADD Microtech (ADDM) reserves the right to make changes to its products or to discontinue any integrated circuit product or service without notice, and advises its customers to obtain the latest version of relevant information to verify, before placing orders, that the information being relied on is current. A few applications using integrated circuit products may involve potential risks of death, personal injury, or severe property or environmental damage. ADDM integrated circuit products are not designed, intended, authorized, or warranted to be suitable for use in life-support applications, devices or systems or other critical applications. Use of ADDM products in such applications is understood to be fully at the risk of the customer. In order to minimize risks associated with the customer's applications, the customer should provide adequate design and operating safeguards. ADDM assumes to no liability to customer product design or application support. ADDM warrants the performance of its products to the specifications applicable at the time of sale. U.S. Asia Pacific region ADD Microtech Inc. 492 Altamont Drive Milpitas, CA 95035 ADD Microtech Corp 3F, 132, Sec. 4, Chung Hsiao E. Rd., Taipei, Taiwan T E L : (408) 9410420 F A X : (408) 9410864 T E L : 2-27760166 F A X : 2-27764208 Copyright 2001, ADD Microtech Corp. 10 www.addmtek.com