AMC384XBM

AMC DOC. #: AMC3842B_C (LF) March 2004 ® AMC3842B/43B CURRENT MODE PWM CONTROLLER FEATURES ADD MICROTECH CORP. DESCRIPTION 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 200µA 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 Low Start-Up current ( typ. 200µA) 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. PACKAGE PIN OUT COMP VFB ISENSE RT/CT VREF VCC OUTPUT GND Off-line flyback or forward converters. DC-to-DC buck or boost converter. Monitor Power Supply AVAILABLE OPTIONS Device AMC3842B AMC3843B Start-UP Max. Duty Hysteresis Voltage Cycle 16V 8.4V 6V 0.8V < 100% < 100% COMP NC VFB NC ISENSE NC RT/CT 8-Pin Plastic DIP (Top View) VREF NC VCC VC OUTPUT GND PWR RT/CT COMP VFB ISENSE VREF VCC OUTPUT GND 14-Pin Plastic S.O.I.C. Surface Mount (Top View) 8-Pin Plastic S.O.I.C. Surface Mount (Top View) ORDER INFORMATION Plastic DIP-8 Plastic SO-14 Plastic SO-8 M D DM TA (OC) 8-pin 14-pin 8-pin 0 to 70 AMC384XBM AMC384XBD AMC384XBDM 0 to 70 AMC384XBMF(Lead Free) AMC384XBDF(Lead Free) AMC384XBDMF(Lead Free) Note: 1.All surface-mount packages are available in Tape & Reel. Append the letter “T” to part number (i.e. AMC384XBDT, or AMC384XBDMT). 2.The letter ”F” is marked for Lead Free process. Copyright © 2002, ADD Microtech Corp. 1 www.addmtek.com AMC DOC. #: AMC3842B_C (LF) March 2004 AMC3842B/43B CURRENT MODE PWM CONTROLLER (Note 1) ABSOLUTE MAXIMUM RATINGS 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, θJA D PACKAGE: Thermal Resistance-Junction to Ambient, θJA DM PACKAGE: Thermal Resistance-Junction to Ambient, θJA Junction Temperature Calculation: 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. 95 OC/W 120 OC/W 165 OC/W Copyright © 2002, ADD Microtech Corp. 2 www.addmtek.com AMC DOC. #: AMC3842B_C (LF) March 2004 AMC3842B/43B CURRENT MODE PWM CONTROLLER BLOCK DIAGRAM 7 (12) VCC Internal Bias U.V.L.O. 5V EN VREF 36V VREF 8 (14) 5 (9) GND VREF Good Logic 7 (11) PWR Error Amp 2R R 1V Current Sense R PWM Latch VC VFB 2 ( 3) OUTPUT COMP 1 (1) S 6 (10) 3 ( 5) T Oscillator CURRENT SENSE RT/CT 4 (7) PWR 5 (8) GND ( ) 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 © 2002, ADD Microtech Corp. 3 www.addmtek.com AMC DOC. #: AMC3842B_C (LF) March 2004 AMC3842B/43B CURRENT MODE PWM CONTROLLER Supply Voltage Input Voltage RECOMMENDED OPERATING CONDITIONS Recommended Operating Conditions Parameter Symbol Min. Typ. Max. VCC / VC 30 VI,RT/CT VI,ISENSE/VFB VO, Output ICC IO IO(REF) CT fOSC TA 0 0 5.5 30 25 200 -20 100 0 500 70 Units V V V mA mA mA nF KHz O C Output Voltage Supply Current Average Output Current Reference Output Current Timing Capacitor Oscillator Frequency Operating Free-air Temperature 1 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 TJ = 25 OC, IREF = 1mA 12V ≤ VCC ≤ 25V,TJ = 25 OC 1mA ≤ IREF ≤ 20mA TJ = 25 OC TJ = 25 OC 12V ≤ VCC ≤ 25V TMIN ≤ TA ≤ TMAX 4.9 5.0 6 6 -100 52 0.2 5 1.7 2.85 0.9 3.00 1.0 70 -3.0 3.15 1.1 -10 5.1 20 25 -180 V mV mV mA KHz % % V V/V V dB µA -30 1.0 COMP = 5V 12V ≤ VCC ≤ 25V (note 8) Copyright © 2002, ADD Microtech Corp. 4 www.addmtek.com AMC DOC. #: AMC3842B_C (LF) March 2004 AMC3842B/43B CURRENT MODE PWM CONTROLLER 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 Output Low Level Output High Level Rise Time (note 7) Fall Time (note 7) Under-Voltage Lockout Section Start Threshold Min. Operating Voltage PWM Section IBIAS VI(EA) GVO UGBW PSRR ISINK ISOURCE VOH VOL COMP = 2.5V 2.42 65 2V ≤ VO ≤ 4V O TJ = 2 5 C 0.7 60 12V ≤ VCC ≤ 25V VFB = 2.7V, COMP = 1.1V 2 VFB = 2.3V, COMP = 5.0V -0.5 VFB = 2.3V, RL = 15KΩ to GND 5 VFB = 2.7V, RL = 15KΩ to VREF ISINK = 20mA ISINK = 200mA ISOURCE = 20mA ISOURCE = 200mA TJ = 25 OC, CL = 1nF TJ = 25 OC, CL = 1nF AMC3842B AMC3843B AMC3842B AMC3843B AMC3842B/43B AMC3842B AMC3843B VFB = ISENSE = 0V ICC = 25mA -0.1 2.50 90 1 70 7 -1.0 6 0.7 0.1 1.4 13.5 13.0 50 50 16.0 8.4 10 7.6 97 0.2 0.5 14 35 -2 2.58 1.1 0.4 2.2 µA V dB MHz dB mA mA V V VOL VOH tr tf V V 13 12 150 150 17.5 9.0 11.5 8.2 100 0.35 1.0 17 ns ns VTH(ST) 14.5 7.8 8.5 7.0 94 V V Maximum Duty Cycle Total Standby Current Startup Current Operating Supply Current Zener Voltage note 6: note 7: note 8: note 9: ICC VZ % mA mA V 30 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 © 2002, ADD Microtech Corp. 5 www.addmtek.com AMC DOC. #: AMC3842B_C (LF) March 2004 AMC3842B/43B CURRENT MODE PWM CONTROLLER Application Information Error Amp 2R R 1V Current Sense Comparator COMP Rf RS Cf ISENSE GND Fig. 1. Current Sense Circuit Peak current (IS) is set by: IS(MAX) = 1V/RS VREF 2.5V Error Amp Zi VFB 0.5mA RT/CT CT Zf COMP GND RT Fig. 2. Error Amplifier Configuration - the amplifier can source or sink up to 0.5mA Fig. 3. Oscillator Section For RT < 5K, f = 1.72 RTCT VREF RT 2N2222 100K COMP VREF VCC VCC 0.1µF 1K, 1W Output 0.1µF GND CT 4.7K 1K Error AMP Adjust 4.7K VFB 5K ISENSE Adjust ISENSE Output RT/CT GND 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 © 2002, ADD Microtech Corp. 6 www.addmtek.com AMC DOC. #: AMC3842B_C (LF) March 2004 AMC3842B/43B CURRENT MODE PWM CONTROLLER Application Information (continued) 1K VREF COMP Shutdown 330Ω ISENSE Shutdown 500Ω 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 0.1µF RT RT/CT CT R2 ISENSE C R1 RSENSE ISENSE 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 © 2002, ADD Microtech Corp. 7 www.addmtek.com AMC DOC. #: AMC3842B_C (LF) March 2004 AMC3842B/43B CURRENT MODE PWM CONTROLLER 8-Pin Plastic DIP 5 B 8 INCHES MIN TYP MAX MILLIMETERS MIN 9.02 6.10 1.27 0.20 2.92 TYP 9.27 6.35 0.46 1.52 2.54 3.30 7.62 BSC. 15º 7º 15º MAX 10.16 7.11 5.33 2.29 0.38 3.81 1 4 A A 0.355 0.365 0.400 0.240 0.250 0.280 0.018 0.060 0.100 0.210 0.090 0.015 B C F L D F G C K H G D J H 0.050 M J K L M 0.008 0.115 0.130 0.150 0.300 BSC. 7º 8-Pin Plastic S.O.I.C. INCHES MILLIMETERS MAX 0.202 0.163 0.074 0.020 0.035 MIN 4.65 3.66 1.73 0.25 0.38 TYP 1.27 BSC 0.19 0.13 4.80 5.79 0.25 0.25 5.21 8º 6.20 MAX 5.13 4.14 1.88 0.51 0.89 A A B MIN 0.183 0.144 TYP - B F P C 0.068 D 0.010 D G L C F G J 0.015 0.050 BSC 0.007 0.005 0.189 0.228 0.010 0.010 0.205 8º 0.244 SEATING PLAN K M J K L M P Copyright © 2002, ADD Microtech Corp. 8 www.addmtek.com AMC DOC. #: AMC3842B_C (LF) March 2004 AMC3842B/43B CURRENT MODE PWM CONTROLLER 14-Pin Plastic S.O.I.C. INCHES MIN A MILLIMETERS MAX 0.344 0.158 0.069 0.018 0.030 MIN 8.54 3.81 1.35 0.35 0.67 TYP 1.27 BSC 0.19 0.10 4.82 5.79 0.25 0.25 5.21 8º 6.20 MAX 8.74 4.01 1.75 0.46 0.77 TYP - A B B F P 0.336 0.159 C 0.053 D 0.014 G D L C M J F G J K L M P 0.026 0.050 BSC 0.007 0.004 0.189 0.228 0.010 0.010 0.205 8º 0.244 SEATING PLAN K Copyright © 2002, ADD Microtech Corp. 9 www.addmtek.com AMC DOC. #: AMC3842B_C (LF) March 2004 AMC3842B/43B CURRENT MODE PWM CONTROLLER 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. ADD Microtech Inc. 492 Altamont Drive Milpitas, CA 95035 T E L : (408) 9410420 F A X : (408) 9410864 Asia Pacific region ADD Microtech Corp 13F, NO. 287, Sec. 3, Nan Jing E. Rd., Taipei, Taiwan 105 T E L : 2-27132800 F A X : 2-27132805 Copyright © 2002, ADD Microtech Corp. 10 www.addmtek.com