UC2843A-Q1 www.ti.com........................................................................................................................................................................................................ SGLS384 - MAY 2008 CURRENT-MODE PWM CONTROLLER FEATURES 1 * * * * * * * * * * * * * * D PACKAGE (TOP VIEW) Qualified for Automotive Applications Extended Temperature Performance of -40C to 125C Optimized for Off-Line and DC-to-DC Converters Low Start-Up Current (<0.5 mA) Trimmed Oscillator-Discharge Current Automatic Feed-Forward Compensation Pulse-by-Pulse Current Limiting Enhanced Load-Response Characteristics Under-Voltage Lockout With Hysteresis Double-Pulse Suppression High-Current Totem-Pole Output Internally Trimmed Bandgap Reference 500-kHz Operation Low RO Error Amp COMP VFB ISENSE RT/CT 1 8 2 7 3 6 4 5 VREF VCC OUTPUT GND DESCRIPTION/ORDERING INFORMATION The UC2843A control IC is a pin-for-pin compatible improved version of the UC2843. Providing the necessary features to control current mode switched mode power supplies, this device has the following improved features. Start up current is specified to be less than 0.5 mA. Oscillator discharge is trimmed to 8.3 mA. During undervoltage lockout, the output stage can sink at least 10 mA at less than 1.2 V for VCC over 5 V. PART NUMBER UVLO ON UVLO OFF MAXIMUM DUTY CYCLE UC2843A 8.5 V 7.9 V <100% ORDERING INFORMATION (1) PACKAGE (2) TA -40C to 125C (1) (2) SOIC-8 - D8 Reel of 2500 ORDERABLE PART NUMBER UC2843AQD8RQ1 TOP-SIDE MARKING UC2843AQ For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI web site at www.ti.com. Package drawings, standard packing quantities, thermal data, symbolization, and PCB design guidelines are available at www.ti.com/sc/package. 1 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright (c) 2008, Texas Instruments Incorporated UC2843A-Q1 SGLS384 - MAY 2008........................................................................................................................................................................................................ www.ti.com FUNCTIONAL BLOCK DIAGRAM VCC 7 34 V UVLO S/R GND 5 5-V REF 8 VREF 5V 50 mA 7 VC 6 Output 5 GND 2.5 V Internal Bias VREF Good Logic RT/CT 4 Osc Error Amp VFB 2 COMP 1 ISENSE 3 S 2R R R 1V PWM Latch Current Sense Comparator ABSOLUTE MAXIMUM RATINGS (1) (2) over operating free-air temperature range (unless otherwise noted) VCC voltage (low impedance source) VCC voltage (ICC mA) IO VALUE UNIT 30 V Self limiting Output current 1 A Output energy (capacitive load) 5 J -0.3 to 6.3 V Error amplifier output sink current 10 mA Power dissipation at TA < 25C (14-pin D package) 1 W JA Package thermal impedance (3) 97 C/W Tstg Storage temperature range -65 to 150 C 260 C Analog inputs (pins 3 and 5) Lead temperature soldering 1,6 mm (1/16 inch) from case for 10 seconds (1) (2) (3) 2 Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. Unless otherwise indicated, voltages are reference to ground, and currents are positive into and negative out of the specified terminals. Long-term high-temperature storage and/or extended use at maximum recommended operating conditions may result in a reduction of overall device life. See http://www.ti.com/ep_quality for additional information on enhanced plastic packaging. Submit Documentation Feedback Copyright (c) 2008, Texas Instruments Incorporated Product Folder Link(s): UC2843A-Q1 UC2843A-Q1 www.ti.com........................................................................................................................................................................................................ SGLS384 - MAY 2008 ELECTRICAL CHARACTERISTICS TA = -40C to 125C, VCC = 15 V (1), RT = 10 k, CT = 3.3 nF, TA = TJ (unless otherwise stated) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT 4.95 5.0 5.05 V Reference Section Output voltage TJ = 25C, IO = 1 mA Line regulation voltage VIN = 12 V to 25 V 6 20 Load regulation voltage IO = 1 mA to 20 mA 6 25 mV 0.2 0.4 mV/C Temperature stability (2) (3) Total output variation voltage Line, load, temperature Output noise voltage f = 10 Hz to 10 kHz TJ = 25C 4.9 Long term stability 1000 hours TA = 125C Output short-circuit current 5.1 V V 50 -30 mV 5 25 mV -100 -180 mA 52 57 kHz 0.2 1 % Oscillator Section Initial accuracy (4) TJ = 25C Voltage stability VCC = 12 V to 25 V Temperature stability TA = MIN to MAX Amplitude peak-to-peak V pin 7 Discharge current (5) 47 5 % 1.7 V pin 7 = 2 V TJ = 25C 7.8 TJ = Full range 7.5 8.3 V 8.8 8.8 mA Error Amplifier Section Input voltage COMP = 2.5 V 2.45 Input bias current Open loop voltage gain (AVOL) VO = 2 V to 4 V Unity gain bandwidth (3) TJ = 25C PSRR VCC = 12 V to 25 V Output sink current FB = 2.7 V, COMP = 1.1 V Output source current FB = 2.3 V, COMP = 5 V VOUT high FB = 2.3 V, RL = 15 k to GND VOUT low FB = 2.7 V, RL = 15 k to VREF 2.5 2.55 V -0.3 -1 A 65 90 dB 0.7 1 MHz 60 70 dB 2 6 mA -0.5 -0.8 mA 5 6 V 0.7 1.1 V 3 3.15 V/V 1 1.1 Current Sense Section Gain (6) (7) Maximum input signal PSRR (6) 2.85 (6) COMP = 5 V (1) (2) (3) (4) (5) (6) (7) V 70 -2 -10 A ISENSE = 0 V to 2 V 150 300 ns Input bias current Delay to output (3) 0.9 VCC = 12 V to 25 V dB Adjust VCC above the start threshold before setting at 15 V. Temperature stability, sometimes referred to as average temperature coefficient, is described by the equation: Temperature Stability = (VREF (max) - VREF (min))/(TJ (max) - TJ (min)). VREF (max) and VREF (min) are the maximum and minimum reference voltage measured over the appropriate temperature range. Note that the extremes in voltage do not necessarily occur at the extremes in temperature. Specified by design. Output frequency equals oscillator frequency for the UC2843A. This parameter is measured with RT = 10 k to VREF. This contributes approximately 300 A of current to the measurement. The total current flowing into the RT/RC pin is approximately 300 A higher than the measured value. Parameter measured at trip point of latch with VFB at 0 V. Gain is defined by: A = VCOMP/VSENSE; 0 VSENSE 0.8 V. Submit Documentation Feedback Copyright (c) 2008, Texas Instruments Incorporated Product Folder Link(s): UC2843A-Q1 3 UC2843A-Q1 SGLS384 - MAY 2008........................................................................................................................................................................................................ www.ti.com ELECTRICAL CHARACTERISTICS (continued) TA = -40C to 125C, VCC = 15 V, RT = 10 k, CT = 3.3 nF, TA = TJ (unless otherwise stated) PARAMETER TEST CONDITIONS MIN TYP MAX IOUT = 20 mA 0.1 0.4 IOUT = 200 mA 15 2.2 UNIT Output Section (OUT) Low level output voltage High level output voltage Rise time (8) Fall time (8) UVLO saturation IOUT = -20 mA 13 13.5 IOUT = -200 mA 12 13.5 CL = 1 nF TJ = 25C CL = 1 nF TJ = 25C V V 50 150 ns 50 150 ns 0.7 1.2 V 7.8 8.4 9 V 7 7.6 8.2 V 94 96 100 % 0 % 0.3 0.5 mA 11 17 mA VCC = 5 V, IOUT = 10 mA Undervoltage Lockout Section (UVLO) Start threshold Minimum operation voltage after turn on PWM Section Maximum duty cycle Minimum duty cycle Total Standby Current Start-up current Operating supply current FB = 0 V, SENSE = 0 V VCC internal zener voltage ICC = 25 mA (8) 4 30 34 V Specified by design. Submit Documentation Feedback Copyright (c) 2008, Texas Instruments Incorporated Product Folder Link(s): UC2843A-Q1 UC2843A-Q1 www.ti.com........................................................................................................................................................................................................ SGLS384 - MAY 2008 PARAMETER MEASUREMENT INFORMATION 2.5 V 0.5 mA VFB Zi Comp Zf A. 2 1 The error amplifier can source up to 0.5 mA and sink up to 2 mA. Figure 1. Error Amp Configuration ICC VCC On/Off Command to Rest of IC <17 mA UC2843A VON 8.4 V VOFF 7.6 V < 0.5 mA VCC VOFF VON During UVLO, the output is low. Figure 2. Undervoltage Lockout Error Amp 2R IS R 1 R 3 RS Current Sense Comparator Current Sense C 5 A. COMP 1V GND Peak current (Is) is determined by the formula: Ismax = 1.0 V/RS A small RC filter may be required to supress switch transients. Figure 3. Current Sense Circuit Submit Documentation Feedback Copyright (c) 2008, Texas Instruments Incorporated Product Folder Link(s): UC2843A-Q1 5 UC2843A-Q1 SGLS384 - MAY 2008........................................................................................................................................................................................................ www.ti.com PARAMETER MEASUREMENT INFORMATION (continued) Error Amplifier Open-Loop Frequency Response Output Saturation Characteristics 4 Voltage Gain - dB 3 TA = -55C 2 1 Source Sat (VCC - VOH) TA = 25C 80 0 60 -45 40 f 20 -90 -135 AV Phase - Saturation Voltage - V VCC = 15 V -180 0 Sink Sat (VOL) 0 .01 .02 .03 .04 .05 .07 .1 .2 .3 .4 .5 10 .7 100 Output Current, Source or Sink - A Figure 4. 6 1k 10k 100k 1M 10M 1 Frequency - Hz Figure 5. Submit Documentation Feedback Copyright (c) 2008, Texas Instruments Incorporated Product Folder Link(s): UC2843A-Q1 UC2843A-Q1 www.ti.com........................................................................................................................................................................................................ SGLS384 - MAY 2008 APPLICATION INFORMATION Oscillator Frequency vs Timing Resistance Maximum Duty Cycle vs Timing Resistor Figure 6. Oscillator VREF RT 4.7 kW 1 kW Error Amp Adjust 4.7 kW 2N2222 100 kW VCC UC2843A 5 kW ISENSE Adjust 1 COMP VREF 8 2 VFB VCC 7 3 ISENSE OUTPUT 6 4 RT/CT GND 5 0.1 F 0.1 F 1 kW 1 W OUTPUT GND CT A. High peak currents associated with capacitive loads necessitate careful grounding techniques. Timing and bypass capacitors should be connected close to pin 5 in a single point ground. The transistor and 5k potentiometer are used to sample the oscillator waveform and apply an adjustable ramp to pin 3. Figure 7. Open-Loop Laboratory Text Fixture Submit Documentation Feedback Copyright (c) 2008, Texas Instruments Incorporated Product Folder Link(s): UC2843A-Q1 7 UC2843A-Q1 SGLS384 - MAY 2008........................................................................................................................................................................................................ www.ti.com UC2843A VREF 8 RT 0.1 F A fraction of the oscillator ramp can be resistively summed with the current sense signal to provide slope compensation for converters requiring duty cycles over 50%. Note that capacitor C forms a filter with R2 to suppress the leading-edge switch spikes. RT/CT 4 CT ISENSE R1 R2 ISENSE 3 C RSENSE Figure 8. Slope Compression R1 5W 1W 117 VAC T1 (Note 2) VARO VM 68 R12 4.7 kW 2W C1 250 F 250 V R5 2 150 kW 1 C14 100 pF COM D7 USF1002 D3 1N3612 C12 2200 F 16 V N12 C13 2200 F 16 V N12 C3 22 F C4 47 F 25 V R9 68 W 3W +12 V 12 V COM -12 V NC D8 UES1002 R7 22 W UC2843A 8 Q1 UFN833 6 R6 10 kW C5 .01 F C11 4700 F 10 V NP D2 1N3612 7 C10 N5 4700 F 10 V D4 1N3613 R3 20 kW C2 100 F 25 V L1 (Note 2) +5 V C9 3300 pF 600 V R2 56 kW 2W R4 4.7 kW D6 USD945 C8 680 pF 600V 3 4 C6 .0022 F 5 USD1120 C7 470 pF R8 1 kW R13 20 kW R10 0.55 W 1W D5 1N3613 R11 2.7 kW 2W Power Supply Specifications 1. 2. 3. 4. 5. Input Voltage 95 VAC to 130 VAC (50 Hz/60 Hz) Line Isolation 3750 V Switching Frequency 40 kHz Efficiency, Full Load 70% Output Voltage: A. 5 V 5%; 1-A to 4-A Load B. 12 V 3%; 0.1-A to 0.3-A Load; Ripple voltage: 100 mV P-P Max C. -12 V 3%; 0.1-A to 0.3-A Load; Ripple voltage: 100 mV P-P Max Figure 9. Off-Line Flyback Regulator 8 Submit Documentation Feedback Copyright (c) 2008, Texas Instruments Incorporated Product Folder Link(s): UC2843A-Q1 PACKAGE OPTION ADDENDUM www.ti.com 19-Jan-2009 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Eco Plan (2) Qty UC2843AQD8RG4Q1 ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM UC2843AQD8RQ1 ACTIVE SOIC D 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM Lead/Ball Finish MSL Peak Temp (3) (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. 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