TL2843D

Sample & Buy Product Folder Support & Community Tools & Software Technical Documents TL2842, TL2843, TL2844, TL2845 TL3842, TL3843, TL3844, TL3845 SLVS038I – JANUARY 1989 – REVISED JULY 2016 TLx84x Current-Mode PWM Controllers 1 Features 3 Description • • • • • • • • • • • • The TL284x and TL384x series of control integrated circuits provide the features that are necessary to implement off-line or DC-to-DC fixed-frequency current-mode control schemes, with a minimum number of external components. Some of the internally implemented circuits are an undervoltage lockout (UVLO), featuring a start-up current of less than 1 mA, and a precision reference trimmed for accuracy at the error amplifier input. Other internal circuits include logic to ensure latched operation, a pulse-width modulation (PWM) comparator (that also provides current-limit control), and a totem-pole output stage designed to source or sink high-peak current. The output stage, suitable for driving Nchannel MOSFETs, is low when it is in the off state. 1 Optimized for Off-Line and DC-to-DC Converters Low Start-Up Current (< 1 mA) Automatic Feed-forward compensation Pulse-by-Pulse Current Limiting Enhanced Load-Response Characteristics Undervoltage Lockout With Hysteresis Double-Pulse Suppression High-Current Totem-Pole Output Internally Trimmed Bandgap Reference 500-kHz Operation Error Amplifier With Low Output Resistance Designed to be Interchangeable with UC2842 and UC3842 Series PART NUMBER 2 Applications • • Device Information(1) Switching regulators of any polarity Transformer-coupled DC/DC convertors TLx84x PACKAGE BODY SIZE (NOM) SOIC (8) 4.90 mm × 3.91 mm SOIC (14) 8.65 mm × 3.91 mm PDIP (8) 9.81 mm × 6.35 mm (1) For all available packages, see the orderable addendum at the end of the datasheet. Device Pinout Drawing SOIC (14) COMP 1 14 REF NC 2 13 NC VFB 3 12 VCC NC 4 11 VC ISENSE 5 10 OUTPUT NC 6 9 GND RT/CT 7 8 POWER_GROUND Device Pinout Drawing SOIC or PDIP (8) COMP 1 8 REF VFB 2 7 VCC ISENSE 3 6 OUTPUT RT/CT 4 5 GND Not to scale NC — No internal connection Not to scale 1 An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications, intellectual property matters and other important disclaimers. PRODUCTION DATA. TL2842, TL2843, TL2844, TL2845 TL3842, TL3843, TL3844, TL3845 SLVS038I – JANUARY 1989 – REVISED JULY 2016 www.ti.com Table of Contents 1 2 3 4 5 6 7 Features .................................................................. Applications ........................................................... Description ............................................................. Revision History..................................................... Pin Configuration and Functions ......................... Specifications......................................................... 1 1 1 2 3 4 6.1 6.2 6.3 6.4 6.5 6.6 4 4 4 4 5 6 Absolute Maximum Ratings ...................................... ESD Ratings.............................................................. Recommended Operating Conditions....................... Thermal Information .................................................. Electrical Characteristics........................................... Typical Characteristics .............................................. Detailed Description .............................................. 8 7.1 Overview ................................................................... 8 7.2 Functional Block Diagram ......................................... 8 7.3 Feature Description................................................... 8 7.4 Device Functional Modes.......................................... 9 8 Application and Implementation ........................ 10 8.1 Typical Application .................................................. 10 9 Power Supply Recommendations...................... 12 10 Layout................................................................... 13 10.1 Layout Guidelines ................................................. 13 10.2 Layout Example .................................................... 14 11 Device and Documentation Support ................. 15 11.1 11.2 11.3 11.4 11.5 11.6 Receiving Notification of Documentation Updates Related Links ........................................................ Community Resources.......................................... Trademarks ........................................................... Electrostatic Discharge Caution ............................ Glossary ................................................................ 15 15 15 15 15 15 12 Mechanical, Packaging, and Orderable Information ........................................................... 15 4 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision H (January 2015) to Revision I Page • Updated pinout images........................................................................................................................................................... 3 • Changed TL984x to TL384x in Recommended Operating Conditions................................................................................... 4 • Changed TLx842, TLx844 to TLx842, TLx843 and TLx843, TLx845 to TLx844, TLx845 in Pulse-Width-Modulator Section.................................................................................................................................................................................... 6 • Added Receiving Notification of Documentation Updates section and Community Resources section .............................. 15 Changes from Revision G (February 2008) to Revision H Page • Added Applications, Device Information table, Pin Functions table, ESD Ratings table, Thermal Information table, Typical Characteristics, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section. ................................................................................................. 1 • Deleted Ordering Information table. ....................................................................................................................................... 1 2 Submit Documentation Feedback Copyright © 1989–2016, Texas Instruments Incorporated Product Folder Links: TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 TL2842, TL2843, TL2844, TL2845 TL3842, TL3843, TL3844, TL3845 www.ti.com SLVS038I – JANUARY 1989 – REVISED JULY 2016 5 Pin Configuration and Functions D Package 14-Pin SOIC Top View D or P Package 8-Pin SOIC or PDIP Top View COMP 1 14 REF NC 2 13 NC VFB 3 12 VCC NC 4 11 VC ISENSE 5 10 OUTPUT NC 6 9 GND RT/CT 7 8 POWER_GROUND COMP 1 8 REF VFB 2 7 VCC ISENSE 3 6 OUTPUT RT/CT 4 5 GND Not to scale NC — No internal connection Not to scale Pin Functions PIN TYPE DESCRIPTION NAME D D or P COMP 1 1 I/O Error amplifier compensation pin GND 9 5 — Device power supply ground terminal ISENSE 5 3 I 2, 4, 6, 13 — — Do not connect OUTPUT 10 6 O PWM Output POWER GROUND 8 — — Output PWM ground terminal REF 14 8 O Oscillator voltage reference RT/CT 7 4 I/O Oscillator RC input VC 11 — — Output PWM positive voltage supply VCC 12 7 — Device positive voltage supply VFB 3 2 I NC Copyright © 1989–2016, Texas Instruments Incorporated Current sense comparator input Error amplifier input Submit Documentation Feedback Product Folder Links: TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 3 TL2842, TL2843, TL2844, TL2845 TL3842, TL3843, TL3844, TL3845 SLVS038I – JANUARY 1989 – REVISED JULY 2016 www.ti.com 6 Specifications 6.1 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted) (1) MIN MAX UNIT VCC Supply Voltage (2) Self limiting VI Analog input voltage range, VFB and ISENSE –0.3 6.3 V VO Output Voltage 35 V VI Input Voltage, VC and D Package only 35 V ICC Supply current 30 mA IO Output current ±1 A error amplifier output sink current 10 mA 150 °C TJ — Virtual junction temperature Output energy (capacitive load) Tstg (1) (2) Storage temperature –65 5 µJ 150 °C Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. All voltages are with respect to the device GND pin. 6.2 ESD Ratings VALUE V(ESD) (1) (2) Electrostatic discharge Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins (1) 3000 Charged device model (CDM), per JEDEC specification JESD22-C101, all pins (2) 3000 UNIT V JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. JEDEC document JEP157 states that 250-V CDM allows safe manufacturing with a standard ESD control process. 6.3 Recommended Operating Conditions over operating free-air temperature range (unless otherwise noted) MIN VCC and VC (1) Supply Voltage VI, RT/CT Input Voltage VI, VFB and ISENSE Input Voltage VO, OUTPUT TYP MAX UNIT 30 V 0 5.5 V 0 5.5 V Output voltage 0 30 V VO, POWER GROUND (1) Output voltage –0.1 1 V ICC Supply current, externally limited 25 mA IO Average output current 200 mA IO(ref) Reference output current fOSC Oscillator frequency TA Operating free-air temperature (1) 100 –20 mA 500 kHz TL284x –40 85 TL384x 0 70 °C These recommended voltages for VC and POWER GROUND apply only to the D package. 6.4 Thermal Information TLx84x THERMAL METRIC (1) RθJA (1) 4 Junction-to-ambient thermal resistance D (SOIC) D (SOIC) P (PDIP) 8 PINS 14 PINS 8 PINS 97 86 85 UNIT °C/W For more information about traditional and new thermal metrics, see the Semiconductor and IC Package Thermal Metrics application report. Submit Documentation Feedback Copyright © 1989–2016, Texas Instruments Incorporated Product Folder Links: TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 TL2842, TL2843, TL2844, TL2845 TL3842, TL3843, TL3844, TL3845 www.ti.com SLVS038I – JANUARY 1989 – REVISED JULY 2016 6.5 Electrical Characteristics over operating free-air temperature range, VCC = 15 V (1), RT = 10 kΩ, CT = 3.3 nF (unless otherwise noted) TEST CONDITIONS (2) PARAMETER TL284x TL384x UNIT MIN TYP (2) MAX MIN TYP (2) MAX 4.95 5 5.05 4.9 5 5.1 V 6 20 6 20 mV Reference Section Output voltage IO = 1 mA, TA = 25°C Line regulation VCC = 12 V to 25 V Load regulation IO = 1 mA to 20 mA Temperature coefficient of output voltage Output voltage with worst-case variation VCC = 12 V to 25 V, IO = 1 mA to 20 mA Output noise voltage f = 10 Hz to 10 kHz, TA = 25°C Output-voltage long-term drift After 1000 h at TA = 25°C Short-circuit output current 6 25 6 25 mV 0.2 0.4 0.2 0.4 mV/°C 5.18 V 4.9 5.1 4.82 50 50 µV 5 25 5 25 mV –30 –100 –180 –30 –100 –180 mA 47 52 57 47 52 57 kHz 2 10 Oscillator Section Oscillator frequency (3) TA = 25°C Frequency change with supply voltage VCC = 12 V to 25 V 2 10 Hz/kHz Frequency change with temperature 50 50 Hz/kHz peak-to-peak amplitude at RT/CT 1.7 1.7 V Error-Amplifier Section Feedback input voltage COMP at 2.5 V 2.45 Input bias current Open-loop voltage amplification VO = 2 V to 4 V Gain-bandwidth product 2.50 2.55 –0.3 –1 2.42 2.50 2.58 V –0.3 –2 µA 65 90 65 90 dB 0.7 1 0.7 1 MHz Supply-voltage rejection ratio VCC = 12 V to 25 V 60 70 60 70 dB Output sink current VFB, at 2.7 V, COMP at 1.1 V 2 6 2 6 mA Output source current VFB, at 2.3 V, COMP at 5 V –0.5 –0.8 –0.5 –0.8 mA Hihg-level output voltage VFB, at 2.3 V, RL = 15 kΩ to GND 5 6 5 6 Low-level output voltage VFB, at 2.7 V, RL = 15 kΩ to GND 0.7 1.1 2.85 3 3.13 0.9 1 1.1 V 0.7 1.1 V 2.85 3 3.15 V/V 0.9 1 1.1 Current-sense Section Voltage amplification See (4) (5) Current-sense comparator threshold COMP at 5 V, see (4) Supply-voltage rejection ratio VCC = 12 V to 25 V, see (4) 70 Input bias current Delay time to output 70 V dB –2 –10 –2 –10 µA 150 300 150 300 ns Output Section High-level output voltage IOH = –20 mA 13 13.5 13 13.5 IOH = –200 mA 12 13.5 13 13.5 V IOH = 20 mA 0.1 0.4 0.1 0.4 IOH = 200 mA 1.5 2.2 1.5 2.2 Rise time CL = 1 nF, TA = 25°C 50 150 50 150 ns fall time CL = 1 nF, TA = 25°C 50 150 50 150 ns Low-level output voltage V Undervoltage-Lockout Section Start threshold voltage (1) (2) (3) (4) (5) TLx842, TLx844 15 16 17 14.5 16 17.5 TLx843, TLx845 7.8 8.4 9 7.8 8.4 9 V Adjust VCC above the start threshold before setting it to 15 V. All typical values are at TA = 25°C. Output frequency equals oscillator frequency for the TLx842 and TLx843. Output frequency is one-half the oscillator frequency for the TLx844 and TLx845. These parameters are measured at the trip point of the latch, with VFB at 0 V. Voltage amplification is measured between ISENSE and COMP, with the input changing from 0 V to 0.8 V. Copyright © 1989–2016, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 5 TL2842, TL2843, TL2844, TL2845 TL3842, TL3843, TL3844, TL3845 SLVS038I – JANUARY 1989 – REVISED JULY 2016 www.ti.com Electrical Characteristics (continued) over operating free-air temperature range, VCC = 15 V(1), RT = 10 kΩ, CT = 3.3 nF (unless otherwise noted) Minimum operating voltage after startup TL284x TEST CONDITIONS (2) PARAMETER MIN TYP (2) TL384x MAX MIN TYP (2) MAX TLx842, TLx844 9 10 11 8.5 10 11.5 TLx843, TLx845 7 7.6 8.2 7 7.6 8.02 TLx842, TLx843 95% 97% 100% 95% 97% 100% TLx844, TLx845 46% 48% 50% 46% 48% 50% UNIT V Pulse-Width-Modulator Section Maximum duty cycle Minimum duty cycle 0% 0% Supply Voltage Start-up current 0.5 1 0.5 1 mA Operating supply current VFB and ISENSE at 0 V 11 17 11 17 mA Limiting voltage ICC = 25 mA 34 34 V 6.6 Typical Characteristics 9.2 VTH, Current Sense Input Threshold (A) 1.2 9 IDISCHARGE (mA) 8.8 8.6 8.4 8.2 8 7.8 7.6 7.4 -75 1 0.8 0.6 0.4 Ta = 125 C Ta = 25 C Ta = -55 C 0.2 0 -50 -25 0 25 50 75 Temperature (C) 100 125 150 0 Figure 1. Oscillator Discharge Current vs Temperature for VIN = 15 V and VOSC = 2V 100 40 50 20 0 -50 100 1000 10000 100000 1000000 Freq (Hz) -100 1E+7 D003 Figure 3. Error Amplifier Open-Loop Gain and Phase vs Frequency VCC = 15 V, RL = 100 kΩ, and TA = 25 °C 6 Submit Documentation Feedback DMAX, Maximum Output Duty Cycle (%) Gain (dB) 150 60 -20 10 D002 100 200 Gain Phase 0 8 Figure 2. Current Sense Input Threshold vs Error Amplifier Output Voltage for VIN = 15 V 100 80 2 4 6 VO, Error Amp Output Voltage (V) D001 90 80 70 60 50 40 0.1 0.2 0.3 0.5 0.7 1 2 3 RT, Timing Resistor (kOhm) 4 5 6 7 8 10 D004 Figure 4. Max Output Duty Cycle vs Timing Resistor for VCC = 15, CT = 3.3 nF, TA = 25 °C Copyright © 1989–2016, Texas Instruments Incorporated Product Folder Links: TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 TL2842, TL2843, TL2844, TL2845 TL3842, TL3843, TL3844, TL3845 www.ti.com SLVS038I – JANUARY 1989 – REVISED JULY 2016 10 9 -2 8 -3 -6 7 Source Saturation at 25 C Source Saturation at -55 C 6 Sink Saturation at -55 C 5 Sink Saturation at 25 C 4 -7 3 -8 2 -9 1 -4 -5 -10 0 100 200 300 400 500 600 IO, Output Load Current (mA) 700 180 160 140 ISC (mA) 0 -1 Sink Saturation Voltage (V) Source Saturation Voltage (V) Typical Characteristics (continued) 120 100 80 60 40 -75 0 800 Figure 5. Output Saturation Voltage vs Load Current for VCC = 15 V with 5-ms Input Pulses -25 0 25 50 75 Temperature (C) 100 125 150 D006 Figure 6. Reference Short Circuit Current vs Temperature for VIN = 15 V 0 5.2 Ta = 125 C Ta = 25 C Ta = -40 C -10 5.15 5.1 -20 VREF (V) Reference Voltage Delta (mV) -50 D005 -30 5.05 5 4.95 -40 4.9 -50 4.85 -60 0 20 40 60 80 100 Source Current (mA) 120 140 160 D007 4.8 -75 -50 -25 0 25 50 75 Temperature (C) 100 125 Figure 7. Reference Voltage vs Source Current Figure 8. Reference Voltage vs Temperature Figure 9. Dead Time vs Timing Capacitance Figure 10. Timing Resistance vs Frequency Copyright © 1989–2016, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 150 D008 7 TL2842, TL2843, TL2844, TL2845 TL3842, TL3843, TL3844, TL3845 SLVS038I – JANUARY 1989 – REVISED JULY 2016 www.ti.com 7 Detailed Description 7.1 Overview The TL284x and TL384x series of control integrated circuits provide the features that are necessary to implement off-line or DC-to-DC fixed-frequency current-mode control schemes, with a minimum number of external components. Some of the internally implemented circuits are an undervoltage lockout (UVLO), featuring a startup current of less than 1 mA, and a precision reference trimmed for accuracy at the error amplifier input. Other internal circuits include logic to ensure latched operation, a pulse-width modulation (PWM) comparator (that also provides current-limit control), and a totem-pole output stage designed to source or sink high-peak current. The output stage, suitable for driving N-channel MOSFETs, is low when it is in the off state. Major differences between members of these series are the UVLO thresholds and maximum duty-cycle ranges. Typical UVLO thresholds of 16 V (on) and 10 V (off) on the TLx842 and TLx844 devices make them ideally suited to off-line applications. The corresponding typical thresholds for the TLx843 and TLx845 devices are 8.4 V (on) and 7.6 V (off). The TLx842 and TLx843 devices can operate to duty cycles approaching 100%. A dutycycle range of 0 to 50% is obtained by the TLx844 and TLx845 by the addition of an internal toggle flip-flop, which blanks the output off every other clock cycle. The TL284x-series devices are characterized for operation from −40°C to +85°C. The TL384x devices are characterized for operation from 0°C to 70°C. 7.2 Functional Block Diagram A A. The toggle flip-flop is present only in TL2844, TL2845, TL3844, and TL3845. Pin numbers shown are for the D (14pin) package. 7.3 Feature Description 7.3.1 Pulse-by-Pulse Current Limiting Pulse-by-pulse limiting is inherent in the control scheme. An upper limit on the peak current can be established by simply clamping the error voltage. Accurate current limiting allows optimization of magnetic and power semiconductor elements while ensuring reliable supply operation 8 Submit Documentation Feedback Copyright © 1989–2016, Texas Instruments Incorporated Product Folder Links: TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 TL2842, TL2843, TL2844, TL2845 TL3842, TL3843, TL3844, TL3845 www.ti.com SLVS038I – JANUARY 1989 – REVISED JULY 2016 Feature Description (continued) 7.3.2 Error Amplifier With Low Output Resistance With a low output resistance, various impedance networks may be used on the compensation pin input for error amplifier feedback. 7.3.3 High-Current Totem-Pole Output The output of the TLx84x devices can sink or source up to 1 A of current. 7.4 Device Functional Modes 7.4.1 Shutdown Technique The PWM controller (see Figure 11) can be shut down by two methods: either raise the voltage at ISENSE above 1 V or pull the COMP terminal below a voltage two diode drops above ground. Either method causes the output of the PWM comparator to be high (see Functional Block Diagram). The PWM latch is reset dominant so that the output remains low until the next clock cycle after the shutdown condition at the COMP or ISENSE terminal is removed. In one example, an externally latched shutdown can be accomplished by adding an SCR that resets by cycling VCC below the lower UVLO threshold. At this point, the reference turns off, allowing the SCR to reset. Figure 11. Shutdown Techniques 7.4.2 Slope Compensation A fraction of the oscillator ramp can be summed resistively with the current-sense signal to provide slope compensation for converters requiring duty cycles over 50% (see Figure 12). NOTE Capacitor C forms a filter with R2 to suppress the leading-edge switch spikes. Figure 12. Slope Compensation Copyright © 1989–2016, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 9 TL2842, TL2843, TL2844, TL2845 TL3842, TL3843, TL3844, TL3845 SLVS038I – JANUARY 1989 – REVISED JULY 2016 www.ti.com 8 Application and Implementation NOTE Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI’s customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality. 8.1 Typical Application The following application is an open-loop laboratory test fixture. This circuit demonstrates the setup and use of the TL284x and TL384x devices and their internal circuitry. In the open-loop laboratory test fixture (see Figure 13), high peak currents associated with loads necessitate careful grounding techniques. Timing and bypass capacitors should be connected close to the GND terminal in a single-point ground. The transistor and 5-kΩ potentiometer sample the oscillator waveform and apply an adjustable ramp to the ISENSE terminal. Figure 13. Open-Loop Laboratory Test Fixture 8.1.1 Design Requirements The design techniques in the following sections may be used for power supply PWM applications which fall within the following requirements. • 500-kHz or lower operation • 30-V or less output voltage • 200-mA or less output current 10 Submit Documentation Feedback Copyright © 1989–2016, Texas Instruments Incorporated Product Folder Links: TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 TL2842, TL2843, TL2844, TL2845 TL3842, TL3843, TL3844, TL3845 www.ti.com SLVS038I – JANUARY 1989 – REVISED JULY 2016 Typical Application (continued) 8.1.2 Detailed Design Procedure 8.1.2.1 Current-Sense Circuit A. Peak current (IS) is determined by the formula: may be required to suppress switch transients. IS(max ) = 1V RS A small RC filter formed by resistor Rf and capacitor Cf Figure 14. Current-Sense Circuit Schematic 8.1.2.2 Error-Amplifier Configuration A. Error amplifier can source or sink up to 0.5 mA. Figure 15. Error-Amplifier Configuration Schematic 8.1.2.3 Oscillator Section A. For RT > 5 kΩ: f» 1.72 R T CT Figure 16. Oscillator Section Schematic Copyright © 1989–2016, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 11 TL2842, TL2843, TL2844, TL2845 TL3842, TL3843, TL3844, TL3845 SLVS038I – JANUARY 1989 – REVISED JULY 2016 www.ti.com Typical Application (continued) 8.1.3 Application Curve The application curve shows oscillator characteristics for chosen capacitor and resistor values. ICC, Supply Current (mA) 25 TL2845 where VCC is swept 37 V to 0 V TL2845 where VCC is swept 0 V to 37 V TL2842 where VCC is swept 37 V to 0 V TL2842 where VCC is swept 0 V to 37 V 20 15 10 5 0 0 5 10 15 20 25 30 VCC, Supply Voltage (V) 35 40 D009 Figure 17. Supply Current vs Supply Voltage 9 Power Supply Recommendations See Recommended Operating Conditions for the recommended power supply voltages for the TL284x and TL384x devices. TI also recommends to have a decoupling capacitor on the output of the device's power supply to limit noise on the device input. 12 Submit Documentation Feedback Copyright © 1989–2016, Texas Instruments Incorporated Product Folder Links: TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 TL2842, TL2843, TL2844, TL2845 TL3842, TL3843, TL3844, TL3845 www.ti.com SLVS038I – JANUARY 1989 – REVISED JULY 2016 10 Layout 10.1 Layout Guidelines Always try to use a low EMI inductor with a ferrite type closed core. Some examples would be toroid and encased E core inductors. Open core can be used if they have low EMI characteristics and are located a bit more away from the low power traces and components. Make the poles perpendicular to the PCB as well if using an open core. Stick cores usually emit the most unwanted noise. 10.1.1 Feedback Traces Try to run the feedback trace as far from the inductor and noisy power traces as possible. Also, keep the feedback trace to be as direct as possible and somewhat thick. These two sometimes involve a trade-off, but keeping it away from inductor EMI and other noise sources is the more critical of the two. Run the feedback trace on the side of the PCB opposite of the inductor with a ground plane separating the two. 10.1.2 Input/Output Capacitors When using a low value ceramic input filter capacitor, it should be located as close to the VCC pin of the IC as possible. This will eliminate as much trace inductance effects as possible and give the internal IC rail a cleaner voltage supply. Some designs require the use of a feed-forward capacitor connected from the output to the feedback pin as well, usually for stability reasons. In this case it should also be positioned as close to the IC as possible. Using surface mount capacitors also reduces lead length and lessens the chance of noise coupling into the effective antenna created by through-hole components. 10.1.3 Compensation Components External compensation components for stability should also be placed close to the IC. Surface mount components are recommended here as well for the same reasons discussed for the filter capacitors. These should not be located very close to the inductor either. 10.1.4 Traces and Ground Planes Make all of the power (high current) traces as short, direct, and thick as possible. It is good practice on a standard PCB board to make the traces an absolute minimum of 15 mils (0.381 mm) per Ampere. The inductor, output capacitors, and output diode should be as close to each other possible. This helps reduce the EMI radiated by the power traces due to the high switching currents through them. This will also reduce lead inductance and resistance as well, which in turn reduces noise spikes, ringing, and resistive losses that produce voltage errors. The grounds of the IC, input capacitors, output capacitors, and output diode (if applicable) should be connected close together directly to a ground plane. It would also be a good idea to have a ground plane on both sides of the PCB. This will reduce noise as well by reducing ground loop errors as well as by absorbing more of the EMI radiated by the inductor. For multi-layer boards with more than two layers, a ground plane can be used to separate the power plane (where the power traces and components are) and the signal plane (where the feedback and compensation and components are) for improved performance. On multi-layer boards the use of vias will be required to connect traces and different planes. It is good practice to use one standard via per 200 mA of current if the trace will need to conduct a significant amount of current from one plane to the other. Arrange the components so that the switching current loops curl in the same direction. Due to the way switching regulators operate, there are two power states. One state when the switch is on and one when the switch is off. During each state there will be a current loop made by the power components that are currently conducting. Place the power components so that during each of the two states the current loop is conducting in the same direction. This prevents magnetic field reversal caused by the traces between the two half-cycles and reduces radiated EMI. Copyright © 1989–2016, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 13 TL2842, TL2843, TL2844, TL2845 TL3842, TL3843, TL3844, TL3845 SLVS038I – JANUARY 1989 – REVISED JULY 2016 www.ti.com 10.2 Layout Example LEGEND Power or GND Plane VIA to Power Plane VIA to GND Plane VCC Error signal Current Sense 1 COMP 2 VFB 3 ISENSE 4 RT/CT TLx84x REF 16 VCC 15 OUTPUT 14 GND 13 Output Figure 18. Layout of D-8 or P Package for TLx84x Devices 14 Submit Documentation Feedback Copyright © 1989–2016, Texas Instruments Incorporated Product Folder Links: TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 TL2842, TL2843, TL2844, TL2845 TL3842, TL3843, TL3844, TL3845 www.ti.com SLVS038I – JANUARY 1989 – REVISED JULY 2016 11 Device and Documentation Support 11.1 Receiving Notification of Documentation Updates To receive notification of documentation updates, navigate to the device product folder on ti.com. In the upper right corner, click on Alert me to register and receive a weekly digest of any product information that has changed. For change details, review the revision history included in any revised document. 11.2 Related Links The table below lists quick access links. Categories include technical documents, support and community resources, tools and software, and quick access to sample or buy. Table 1. Related Links PARTS PRODUCT FOLDER SAMPLE & BUY TECHNICAL DOCUMENTS TOOLS & SOFTWARE SUPPORT & COMMUNITY TL2842 Click here Click here Click here Click here Click here TL2843 Click here Click here Click here Click here Click here TL2844 Click here Click here Click here Click here Click here TL2845 Click here Click here Click here Click here Click here TL3842 Click here Click here Click here Click here Click here TL3843 Click here Click here Click here Click here Click here TL3844 Click here Click here Click here Click here Click here TL3845 Click here Click here Click here Click here Click here 11.3 Community Resources The following links connect to TI community resources. Linked contents are provided "AS IS" by the respective contributors. They do not constitute TI specifications and do not necessarily reflect TI's views; see TI's Terms of Use. TI E2E™ Online Community TI's Engineer-to-Engineer (E2E) Community. Created to foster collaboration among engineers. At e2e.ti.com, you can ask questions, share knowledge, explore ideas and help solve problems with fellow engineers. Design Support TI's Design Support Quickly find helpful E2E forums along with design support tools and contact information for technical support. 11.4 Trademarks E2E is a trademark of Texas Instruments. All other trademarks are the property of their respective owners. 11.5 Electrostatic Discharge Caution These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. 11.6 Glossary SLYZ022 — TI Glossary. This glossary lists and explains terms, acronyms, and definitions. 12 Mechanical, Packaging, and Orderable Information The following pages include mechanical, packaging, and orderable information. This information is the most current data available for the designated devices. This data is subject to change without notice and revision of this document. For browser-based versions of this data sheet, refer to the left-hand navigation. Copyright © 1989–2016, Texas Instruments Incorporated Submit Documentation Feedback Product Folder Links: TL2842 TL2843 TL2844 TL2845 TL3842 TL3843 TL3844 TL3845 15 PACKAGE OPTION ADDENDUM www.ti.com 9-Nov-2021 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) (4/5) (6) TL2842D ACTIVE SOIC D 14 50 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 TL2842 TL2842D-8 ACTIVE SOIC D 8 75 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 TL2842 TL2842DR ACTIVE SOIC D 14 2500 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 TL2842 TL2842DR-8 ACTIVE SOIC D 8 2500 RoHS & Green NIPDAU Level-2-260C-1 YEAR -40 to 85 TL2842 TL2842P ACTIVE PDIP P 8 50 RoHS & Green NIPDAU N / A for Pkg Type -40 to 85 TL2842P TL2843D-8 ACTIVE SOIC D 8 75 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 85 TL2843 TL2843DG4-8 ACTIVE SOIC D 8 75 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 85 TL2843 TL2843DR ACTIVE SOIC D 14 2500 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 85 TL2843 TL2843DR-8 ACTIVE SOIC D 8 2500 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 85 TL2843 TL2843DRE4 ACTIVE SOIC D 14 2500 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 85 TL2843 TL2843DRG4-8 ACTIVE SOIC D 8 2500 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 85 TL2843 TL2843P ACTIVE PDIP P 8 50 RoHS & Green NIPDAU N / A for Pkg Type -40 to 85 TL2843P TL2844D ACTIVE SOIC D 14 50 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 85 TL2844 TL2844D-8 ACTIVE SOIC D 8 75 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 85 TL2844 TL2844DR ACTIVE SOIC D 14 2500 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 85 TL2844 TL2844DR-8 ACTIVE SOIC D 8 2500 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 85 TL2844 TL2844DRG4 ACTIVE SOIC D 14 2500 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 85 TL2844 TL2844P ACTIVE PDIP P 8 50 RoHS & Green NIPDAU N / A for Pkg Type -40 to 85 TL2844P TL2844PE4 ACTIVE PDIP P 8 50 RoHS & Green NIPDAU N / A for Pkg Type -40 to 85 TL2844P TL2845D ACTIVE SOIC D 14 50 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 85 TL2845 Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com 9-Nov-2021 Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) (4/5) (6) TL2845D-8 ACTIVE SOIC D 8 75 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 85 TL2845 TL2845DG4-8 ACTIVE SOIC D 8 75 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 85 TL2845 TL2845DR ACTIVE SOIC D 14 2500 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 85 TL2845 TL2845DR-8 ACTIVE SOIC D 8 2500 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 85 TL2845 TL2845DRG4 ACTIVE SOIC D 14 2500 RoHS & Green NIPDAU Level-1-260C-UNLIM -40 to 85 TL2845 TL2845P ACTIVE PDIP P 8 50 RoHS & Green NIPDAU N / A for Pkg Type -40 to 85 TL2845P TL3842D-8 ACTIVE SOIC D 8 75 RoHS & Green NIPDAU Level-2-260C-1 YEAR 0 to 70 TL3842 TL3842DR ACTIVE SOIC D 14 2500 RoHS & Green NIPDAU Level-2-260C-1 YEAR 0 to 70 TL3842 TL3842DR-8 ACTIVE SOIC D 8 2500 RoHS & Green NIPDAU Level-2-260C-1 YEAR 0 to 70 TL3842 TL3842DRE4-8 ACTIVE SOIC D 8 2500 RoHS & Green NIPDAU Level-2-260C-1 YEAR 0 to 70 TL3842 TL3842P ACTIVE PDIP P 8 50 RoHS & Green NIPDAU N / A for Pkg Type 0 to 70 TL3842P TL3842PE4 ACTIVE PDIP P 8 50 RoHS & Green NIPDAU N / A for Pkg Type 0 to 70 TL3842P TL3843D ACTIVE SOIC D 14 50 RoHS & Green NIPDAU Level-1-260C-UNLIM 0 to 70 TL3843 TL3843D-8 ACTIVE SOIC D 8 75 RoHS & Green NIPDAU Level-1-260C-UNLIM 0 to 70 TL3843 TL3843DR ACTIVE SOIC D 14 2500 RoHS & Green NIPDAU Level-1-260C-UNLIM 0 to 70 TL3843 TL3843DR-8 ACTIVE SOIC D 8 2500 RoHS & Green NIPDAU Level-1-260C-UNLIM 0 to 70 TL3843 TL3843P ACTIVE PDIP P 8 50 RoHS & Green NIPDAU N / A for Pkg Type 0 to 70 TL3843P TL3844D ACTIVE SOIC D 14 50 RoHS & Green NIPDAU Level-1-260C-UNLIM 0 to 70 TL3844 TL3844D-8 ACTIVE SOIC D 8 75 RoHS & Green NIPDAU Level-1-260C-UNLIM 0 to 70 TL3844 TL3844DR ACTIVE SOIC D 14 2500 RoHS & Green NIPDAU Level-1-260C-UNLIM 0 to 70 TL3844 TL3844DR-8 ACTIVE SOIC D 8 2500 RoHS & Green NIPDAU Level-1-260C-UNLIM 0 to 70 TL3844 Addendum-Page 2 Samples PACKAGE OPTION ADDENDUM www.ti.com 9-Nov-2021 Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (°C) Device Marking (3) (4/5) (6) TL3844P ACTIVE PDIP P 8 50 RoHS & Green NIPDAU N / A for Pkg Type 0 to 70 TL3844P TL3844PE4 ACTIVE PDIP P 8 50 RoHS & Green NIPDAU N / A for Pkg Type 0 to 70 TL3844P TL3845D ACTIVE SOIC D 14 50 RoHS & Green NIPDAU Level-1-260C-UNLIM 0 to 70 TL3845 TL3845D-8 ACTIVE SOIC D 8 75 RoHS & Green NIPDAU Level-1-260C-UNLIM 0 to 70 TL3845 TL3845DR ACTIVE SOIC D 14 2500 RoHS & Green NIPDAU Level-1-260C-UNLIM 0 to 70 TL3845 TL3845DR-8 ACTIVE SOIC D 8 2500 RoHS & Green NIPDAU Level-1-260C-UNLIM 0 to 70 TL3845 TL3845P ACTIVE PDIP P 8 50 RoHS & Green NIPDAU N / A for Pkg Type 0 to 70 TL3845P TL3845PE4 ACTIVE PDIP P 8 50 RoHS & Green NIPDAU N / A for Pkg Type 0 to 70 TL3845P (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) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of