AMC3843B

AMC3842B/43B/44B/45B www.addmtek.com DESCRIPTION The AMC3842B/43B/44B/45B 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 start-up current in typical, allowing an efficient bootstrap supply voltage design. The U.V.L.O. thresholds for the AMC3842B/44B are 16V (on) and 10V (off), which are ideal for off-line applications. The corresponding typical threshold for the AMC3843/45BB is 8.4V (on) and 7.6V (off). The AMC3842B/43B can operate within 100% duty cycle and the AMC3844B/45B can operate within 50% duty cycle. APPLICATIONS Off-line flyback or forward converters. DC-to-DC buck or boost converter. Monitor Power Supply CURRENT MODE PWM CONTROLLER FEATURES Low Start-Up current (max. 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 8-Pin Plastic DIP (Top View) AVAILABLE OPTIONS Device AMC3842B AMC3843B AMC3844B AMC3845B Start-UP Voltage 16V 8.4V 16V 8.4V Hysteresis 6V 0.8V 6V 0.8V Max. Duty Cycle < 100% < 100% < 50% < 50% COMP NC VFB NC ISENSE NC RT/CT 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) TA (OC) 0 to 70 0 to 70 Note: ORDER INFORMATION Plastic DIP-8 Plastic SO-14 M 8-pin D 14-pin AMC384XBM AMC384XBD AMC384XBM (Lead Free) AMC384XBD (Lead Free) DM 8-pin Plastic SO-8 AMC384XBDM AMC384XBDM (Lead Free) 1. All surface-mount packages are available in Tape & Reel. AMC384XBDMT). 2. The letter ”F” is marked for Lead Free process. 1 Append the letter “T” to part number (i.e. AMC384XBDT, or Copyright © 2006 ADDtek Corp. DD019_F -- OCTOBER 2006 AMC3842B/43B/44B/45B ABSOLUTE MAXIMUM RATINGS Supply voltage, VCC Output current, IO Analog inputs, VI Error amp output sink current, ISINK(EA) Power dissipation (TA = 25 OC), PD Maximum juncture temperature, TJ Storage temperature range Lead temperature (soldiering, 10 seconds) Note 1: Exceeding these ratings could cause damage to the device. negative out of the specified terminal. All voltages are with respect to Ground. (Note 1) 35V ± 1A -0.3V to 6.3V 10mA 1W 150 OC -65OC to 150OC 260 OC Currents are positive into, 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 © 2006 ADDtek Corp. 2 DD019_F -- OCTOBER 2006 AMC3842B/43B/44B/45B BLOCK DIAGRAM 7 (12) Internal Bias U.V.L.O. 5V EN VREF 36V VCC VREF 8 (14) 5 (9) GND VREF Good Logic Error Amp Current Sense 1V R PWM Latch 7 (11) PWR VC 2R R VFB 2 ( 3) COMP 1 (1) CURRENT SENSE RT/CT OUTPUT S 6 (10) T 3 ( 5) PWR Oscillator 4 ( 7) 5 (8) GND ( ) are 14 Pin S.O.I.C. pin number Note 2: Note 3: Note 4: Note 5: Note 6: 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/44B and 8.4V for 3843B/45B. Hysteresis is 6V for 3842B/44B and 0.8V for 3843B/45B. Toggle flip flop used only in 3844B/45B Copyright © 2006 ADDtek Corp. 3 DD019_F -- OCTOBER 2006 AMC3842B/43B/44B/45B 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 Supply Voltage Input Voltage 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 7); RT = 10K;CT = 3.3nF. Low duty cycle pulse testing techniques are used which maintains junction and case temperatures equal to the ambient temperature. Parameter Reference Section Reference output Voltage VREF TJ = 25 OC, IREF = 1mA 12V ≤ VCC ≤ 25V,TJ = 25 C 1mA ≤ IREF ≤ 20mA TJ = 25 OC O Symbol Test Conditions AMC384XB Min. 4.9 Typ. 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 Max. 5.1 20 25 -180 57 1.0 Units V mV mV mA KHz % % V V/V V dB µA Line Regulation Load Regulation Short Ciruit Output Current ISC Oscillator Section Oscillation Frequency f Frequency Change with Voltage Frequency Change with Temperature (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) Power Supply Rejection Ratio (note 9) PSRR Input Bias Current IBIAS -30 47 TJ = 25 OC 12V ≤ VCC ≤ 25V TMIN ≤ TA ≤ TMAX COMP = 5V 12V ≤ VCC ≤ 25V (note 9) Copyright © 2006 ADDtek Corp. 4 DD019_F -- OCTOBER 2006 AMC3842B/43B/44B/45B ELECTRICAL CHARACTERISTICS (Continued) Error Amplifier Section Input Bias Current Input Voltage Open Loop Voltage Gain Unity Gain Bandwidth (note 8) 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 9) Fall Time (note 9) Under-Voltage Lockout Section Start Threshold Min. Operating Voltage PWM Section IBIAS VI(EA) GVO UGBW PSRR ISINK ISOURCE VOH VOL COMP = 2.5V 2V ≤ VO ≤ 4V TJ = 25 OC 12V ≤ VCC ≤ 25V VFB = 2.7V, COMP = 1.1V VFB = 2.3V, COMP = 5.0V VFB = 2.3V, RL = 15KΩ to GND 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/44B AMC3843B/45B AMC3842B/44B AMC3843B/45B AMC3842B/43B AMC3844B/45B AMC3842B/44B AMC3843B/45B VFB = ISENSE = 0V ICC = 25mA 2.42 65 0.7 60 2 -0.5 5 -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 48 -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 50 0.2 0.2 17 ns ns VTH(ST) 14.5 7.8 8.5 7.0 94 47 V V Maximum Duty Cycle Total Standby Current Startup Current Operating Supply Current Zener Voltage Note 7: Note 8: Note 9: Note 10: Dmax % mA mA V ICC VZ 30 14 35 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 © 2006 ADDtek Corp. 5 DD019_F -- OCTOBER 2006 AMC3842B/43B/44B/45B CHARACTERIZATION CURVES Below characterization curves was referenced by Fig.4 O s cillator D is charge Current vs . Tem perature 9 Maximum Output Duty Cycle vs. Timing Resistor 100 Vcc=15V 8.5 90 80 Dmax 70 (%) 60 Idischg=7.5mA Vosc=2V Idischg (mA) Idischg=8.8mA Vcc=15V Ct=3.3mF TA=25ºC 8 7.5 7 -50 -25 0 25 50 75 100 125 50 40 0 1 2 3 4 5 6 7 8 TA(ºC) RT (KΩ ) C urre nt S e nse Input Thre shol d vs. Error Amp Out put Vol t a ge . 1.2 1 0.8 Vth 0.6 (V) 0.4 TA=125ºC TA=25ºC Error Amp Open-Loop Gain and Phase vs. Frequency 100 80 60 (dB) 40 Phase 90 Vcc=15V Vo=2V to 4V RL=100K 10 100 1K 10K f(Hz) 100K 1M 120 150 180 Gain Ø 30 60 20 0 -20 0.2 0 0 1 2 TA=-40ºC Vcc=15V 3 4 Vo(V) 5 6 7 8 R e fe re nc e Vol t a ge C ha nge vs. S ourc e C urre nt . 60 50 40 30 20 10 0 0 20 40 60 80 100 120 Iref(mA) Copyright © 2006 ADDtek Corp. 6 TA=125ºC TA=25ºC TA=-40ºC Reference Short Circuit Current vs. Temperature. 110 100 90 Isc80 (mA) 70 Vcc=15V RL≤0.1Ω Vcc=15V 60 50 -50 -25 0 25 50 75 100 125 150 TA(ºC) DD019_F -OCTOBER 2006 AMC3842B/43B/44B/45B 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 2.5V Error A mp Zi Zf VFB 0.5mA VREF RT RT/CT CT GND COMP Fig. 3. Oscillator Section Fig. 2. Error Amplifier Configuration - the amplifier can source or sink up to 0.5mA For RT < 5K, f = 1.72 RTCT VREF RT 2N2222 100K COMP VREF VCC 4.7K 1K Error AMP Adjust 4.7K VCC 0.1µF 1K, 1W Output 0.1µF GND 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 CT 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 © 2006 ADDtek Corp. 7 DD019_F -- OCTOBER 2006 AMC3842B/43B/44B/45B 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 R1 RSENSE C ISENSE 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 © 2006 ADDtek Corp. 8 DD019_F -- OCTOBER 2006 AMC3842B/43B/44B/45B PACKAGE 8-Pin Plastic DIP INCHES 8 5 MILLIMETERS MAX MIN 9.02 6.10 TYP 9.27 6.35 5.08 0.46 1.52 2.54 0.25 3.30 7.62 BSC. 15º 0º 7º 15º MAX 10.16 7.11 5.33 0.55 1.65 2.29 0.38 3.81 MIN B TYP A 1 4 0.355 0.365 0.400 0.240 0.250 0.280 0.200 0.210 B A C D 0.014 0.018 0.022 0.356 F L F G 0.045 0.060 0.065 0.100 0.090 1.15 1.27 0.20 2.92 C H 0.050 K H G D J J M 0.008 0.010 0.015 0.115 0.130 0.150 0.300 BSC. 0º 7º K L M 8-Pin Plastic S.O.I.C. INCHES A MILLIMETERS MAX 0.202 MIN 4.65 3.66 1.35 0.25 0.38 TYP 3.95 0.41 0.50 1.27 BSC 0.19 0.13 4.80 0º 5.79 6.00 0.25 0.25 5.21 8º 6.20 MAX 5.13 4.14 1.88 0.51 0.89 MIN A B B P TYP - 0.183 0.144 0.156 0.163 0.068 0.074 C F D D G L C SEATING PLAN K M J 0.010 0.016 0.020 0.015 0.020 0.035 0.050 BSC 0.007 0.005 0.189 0º 0.010 0.010 0.205 8º F G J K L M P 0.228 0.236 0.244 Copyright © 2006 ADDtek Corp. 9 DD019_F -- OCTOBER 2006 AMC3842B/43B/44B/45B 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 P 0.336 0.159 C 0.053 D 0.014 F 0.026 F G D L C M J G J K L M P 0.050 BSC 0.007 0.004 0.189 0.228 0.010 0.010 0.205 8º 0.244 SEATING PLAN K Copyright © 2006 ADDtek Corp. 10 DD019_F -- OCTOBER 2006 AMC3842B/43B/44B/45B IMPORTANT NOTICE ADDtek 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. ADDtek 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 ADDtek 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. ADDtek assumes to no liability to customer product design or application support. ADDtek warrants the performance of its products to the specifications applicable at the time of sale. ADDtek Corp. 9F, No. 20, Sec. 3, Bade Rd., Taipei, Taiwan, 105 TEL: 2-25700299 FAX: 2-25700196 Copyright © 2006 ADDtek Corp. 11 DD019_F -OCTOBER 2006