Texas Instruments. System Power Design for Wall-Powered Application. Dec, 18 th -22 th, 2006 Kevin Lin HPA Asia Market Development

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1 Texas Instruments System Power Design for Wall-Powered Application Dec, 18 th -22 th, 2006 Kevin Lin HPA Asia Market Development

2 Utility AC Line-Powered Systems Consumer Industrial Communication Computing Portfolio Strength in... AC/DC, isolated DC/DC Power factor correction Point-of-load DC/DC Plug-in power modules Hot swap/poe Power distribution FET gate drive Digital power Full System Solutions 2

3 Texas Instruments Power History TI has Built the leading Power Management Business 3

4 Content AC-DC PFC Introduction & Design Considerations Isolated PWM Solutions Introduction DC-DC Buck Design Software Introduction

5 What is Power Factor Correction? Power Factor = Real Power Apparent Power Displacement PF = cos( φ) Linear Load Without Active PFC (PF= 0.80) Line Voltage -V in Distortion PF = I I 1 total Non-linear Load Without Active PFC (PF= 0.55) Line Voltage -V in Line Current -I in PF cos( φ) = 1 + THD Line Current -I in 5

6 Benefits for PFCP Circuits Look at Available System Power: Assume 15A Breaker, 98% η Rectifier, PF=0.55 (Typical Rectifier w/o PFC) P = 120 Vrms 15 A = 970 W If PF = 0.99 Available Power = 1746 W Increases Available Line Power of 80% Power Factor Correction is Widely Used Without Active PFC (PF= 0.55) With Active PFC (PF= 1.0) Increases Current Available from Line Reduces 3rd Harmonic Distortion European Market Requirement EN is following standard Enables Universal Line Operation w/o Mech-Switches No need for switches to handle 120V vs V line voltage Easier to Meet Hold-up Time Requirements Energy is stored at a higher voltage of bulk capacitor Can make Second Stage Design Easier Line Current -I in Line Voltage -V in 6

7 Power Factor Correction V i i V Simple Structure No Regulation Large Harmonics Low Power Factor Relative Complex Regulated Output Low Harmonics High Power Factor 7

8 Boost Topology for PFC Vin L I L I Q Q1 I D C V OUT Most Popular Topology Vout > Vin Ideal for Universal Line Inductor Current = Input Current Many Control ICs Available (a) CCM IL_pk_ccm IL_valley_ccm Switch Current Diode Current t D = V out t on Ts = ; V (V in L + = D V V L ); V in out = = (1 V in D) (V 1 (1 - D) out V in ) IL_pk_crm Switch Current Diode Current (b) CRM t 8

9 PFC Design Considerations Trade-Off in between Performance and Total System Cost Optimum control method Average Current Mode (ACM) Simpler inexpensive control Transition Mode or Critical Mode (DCM) High-efficiency & performance Zero Voltage Transition Mode (ZVT) To Meet System Operation Requirement Higher PF and lower THD features input current harmonics shall comply with IEC PFC bulk capacitor design hold up time; Iripple & voltage rating Appropriate DC filtering capacitor bypass current ripple noise Power sequencing techniques for PFC & PWM stages Safety and EMI requirements (conduction & radiation) System-Board Space & Development Time Limitation Layout & placement issue guideline Thermal dissipation management Stability and Reliability Protection features (OVP, SCP, UVP, OCP, OTP) 9

10 Transition Mode (TM/ DCM) PFC t on Constant On Time Control No Reverse Recovery Current on Boost Diode MOSFET ZVS Turn On is Possible Smaller Inductor Value Variable Switching Frequency Large Ripple Current Requires Larger Input Filter High Current Stress and High Conduction Loss on MOSFET 10

11 TM PFC Operation Principle I pk I L t on In each Switching Cycle I avg = I pk 1 2 V L Input Voltage is Sinusoidal, Inductor Average Current is also Sinusoidal if Ton is Constant = in t on 11

12 Switching Performance Estimation V ds I L V ds I L Because of Transition Mode Operation, No Reverse Recovery Loss Low cost, Standard Diode can be Used Because of Resonance between Boost Inductor and MOSFET Junction Capacitor, Less Turn on Loss can be Realized ZVS can be Achieved if Input Voltage is Less than Half of the Output Voltage Less Turn On Loss is Expected Comparing with CCM Mode 12

13 UCC3818A - 16 Pin CCM PFC Controller Input Voltage Input Sine Voltage Waveform Sine Waveform V IN I IN L IN D1 ID1 V O Output Bus Voltage I O Output Bus Voltage V O AC LINE Current Follow & Commend Real Current Waveform Real Current Waveform I IN R SENSE + R IMO Current Follow & Commend R I R F IMPROVED NOISE IMMUNITY + E/A C Z Q1 GATE DRIVE + PWM V S C O PWM Command PWM Commend LOAD C P LPF I AC V FF MULT TEXT K M SQUARE K G I MO Input Feed Forward Input Feed Forward DIV K D D N V VA E/A + V REF Regulation & Constant Power Regulation & Constant Power 13

14 Average Current vs. TM Mode Smaller Ripple Current Smaller RMS Current Smaller EMI Filter Constant Switching Frequency Suitable for High Power Level Large Switching Loss because of Diode Reverse Recovery Current High Cost Components to Maintain High Efficiency No Reverse Recovery Loss Low Cost Solution Soft Switching Possible Large Current Ripple, Increasing Conduction Loss and Switching Loss Large EMI Filter Variable Switching Frequency Normally Limited to Low Power Level 14

15 UCC Transition Mode PFC Controller Slew Rate Comparator for Improved Transient Response Zero Power Detect to Prevent Over Voltage Conditions under Light Load Over Voltage Protection Open Feedback Protection and Enable Circuits Low Startup & Operating Current 750mA Source/ Sink Peak Gate Drive to Reduce Switching Losses UCC38051 Implements Lower UVLO Start-up Voltage for Compatibility (Typical application: AC Adapters) SOIC/ PDIP Package LCD-TV Power Board AC-DC Open Frame Power Mid to High Power AC Adapters Line Voltage Follow Over Voltage Protection 750mA Source/Sink EVM and Sample ES: Now RTP: Now Slew Rate Comparator ZCS Detection Open Feedback Loop Protection 15

16 UC A - 8 Pin CCM (ACM) PFC Controller Complete 8-pin Power Factor Solution Reduced External Components 500mA Source/ Sink Peak Gate Drive to Reduce Switching Losses Traditional Multiplier Line Voltage Compensation Internal 63KHz Synchronizable Oscillator Average Current Mode Control with Improved Noise Immunity Over Voltage Protection Comparator 8-pin PDIP (P) and (SOIC) (D) packages Traditional Multiplier Line Voltage Follow ATX PC Power LCD-TV and PDP-TV Hi-Power Adapters Maximum Vcc: 40V Average Current Mode 500mA Source/Sink EVM and Sample ES: Now RTP: Now Internal 63KHz Oscillator Over Voltage Protection 16

17 UCC PFC/ PWM Combo Controllers + D1 PRIMARY SECONDARY RECT + VOUT - Feature PFC & PWM Stages Benefit VAC UCC2851X PWRGND GT2 GT1 VCC BIAS - REF Combined PFC and PWM Power Stages in One Chip Trailing Edge/Leading Edge Modulation Built-In Sequencing for Reduced complexity and Cost Minimize Ripple Current in Boost Capacitor SS2 ISENSE2 8 PKLMT VERR 7 3A Sink / 2A Source Gate Drives MOSFET Switching Efficiency Z CAOUT ISENSE1 MOUT IAC GND CT_BUFF D_MAX VSENSE PWM V-LOOP Multiple UVLO Options Optimizes Start-up and Turn-off behaviors for Differing Biasing Schemes and Load Transient Requirements Z VFF VREF REF RT 2 VAOUT 1 Z PFC Stage Transconductance Amplifier Enhanced Transient Response Improved Multiplier Improved Power Factor and THD PWM Stage End Applications: Desktop and Server Computer Power Converters Distribution Power System Front Ends Programmable Max Duty Cycle 1x:2x PFC:PWM Frequency Protects Downstream Power Stage Flexibility for Different PWM Topologies 17

18 Power Factor Correction Controllers Specialized PFC Controllers Zero Voltage Switching PFC (Telecom Rectifiers, >1kW High Power) UC3855A/B ZVT, Higher Frequency UCC3819/A Tracking Boost PFC Avg. I-Mode Transition Mode ZVT PFC+PWM Combination Controllers (Desktops, Flyback, Boost) UCC PFC+PWM, LEM/TEM UCC PFC+PWM, LEM/TEM, Prog.MaxDC UCC28521 UCC28528 PFC+PWM, TEM/TEM, Prog.MaxDC General Purpose Average Current Mode CCM PFC UC3854A/B Improved 16-pin CCM UCC3817/18; UCC3817A/18A BiCMOS UC3854A, LEM UC2853A 8-pin CCM <65KHZ UCC28018/19 UCC28018/19 8-pin 8-pin CCM CCM PFC PFC UCC28070 UCC28070 Interleaved Interleaved CCM CCM PFC PFC Transition Mode or Boundary Mode (Adapters, Lighting Ballasts) UCC28050/51 Improved Transient Resp., Industry Std. Pinout UCC28060 UCC28060 Interleaved Interleaved TM TM PFC PFC Existing Products

19 AC-DC PFC Introduction & Design Considerations Isolated PWM Solutions Introduction DC-DC Buck Design Software Introduction 19

20 Isolated PWM Solutions by Topologies (1) 20

21 Isolated PWM Solutions by Topologies (2) 21

22 Analysis of Isolated PWM Topologies Topology Flyback 1 Switch Forward 2 Switch Forward Half-Bridge Push-Pull Full Bridge Power Level <120 W 150 W to 350 W 400 W to 800 W 300 W to 600 W 50 W to 300 W >800 W Low parts count Single magnetic Wide input-voltage range Low output power Benefits Drawbacks Cost Medium output power Good cross regulation with coupled inductor Potential for >50% duty-cycle Medium output power Power switch = V IN Coupled inductor Clamped transformer reset Medium output power Power switch = V IN Coupled inductor Max duty-cycle < 100% Good core utilization Coupled inductor Both switches ground referenced Small output inductor Max duty-cycle < 100% Resonant switching can improve efficiency Power switch = V IN Coupled inductor Very high output power Max duty-cycle < 100% Efficient transformer design Poor efficiency at high power levels High peak currents Cross regulation problems High-voltage power switch Limited input range Power switch = 2 V IN Transformer reset Limited input range High-side drive circuit required 50% duty-cycle limit Larger inductor value Limited input range High-side drive Volt-second balance of transformer Center-tapped secondary Power switch = 2 V IN Limited input range Center-tapped primary Volt-second balance 4-power switches Top FET drive Volt-second balance Lowest Moderate Moderate Moderate Moderate High 22

23 Quasi-Resonant Operation for Valley Switching + V IN I S V O V GS I MAG L MAG C DS t I P t V DS GATE DRIVE C DS Flyback Conversion I PRI t Switching frequency delay turn-on until both Fsmax and V DS turn-on when resonates to minimum voltage and I DS = 0 Switching frequency clamps variable within a range of 40 khz to 130 khz at maximum for higher line and/or lighter load conditions Turn-off by peak current PWM control I SEC V DS Leakage Inductance energy N x V O t V IN t 23

24 UCC QR Green Mode Controller Full Green Mode Capability in 8-Pins; Multi-Mode Operation Provides Advanced Energy Saving Capability Low Standby Current for System No-Load Power Consumption to 150mW Low Frequency (40KHz); Burst Mode for Better Efficiencies at No-Load Operation Programmable Over Voltage Protection, Line and Load; Over-Current Hiccup Restart Mode Green Mode STATUS Pin Disables PFC Function during Light Load for Energy Savings (Can Disable PFC) Over Voltage Protection +1ATrueDrive Gate Drive Output Bias Supplies for LCD-Monitors, LCD-TV, PDP-TV, Set Top Boxes AC/DC Adapters & Off-line Battery Chargers Energy efficient power supplies up to 200W ES: Now RTP: Now Quasi-Resonant Mode Operation Green Mode STATUS Pin for PFC Disable Pinless Demagnetizing Sense Circuit ZCS Detection Soft Start Programmable Low Standby Current; No-Load Power Consumption to 150mW +1A Sink/ 0.75A Source Gate Drive Current Feedback 24

25 Benefits of Active Clamp Topology Applicable to Forward and Flyback Topologies - Higher efficiency Active Clamp Applied to Either High Side or Low Side Higher Max Duty Cycle Advantages - Possible to go beyond 50% duty cycle that reduces Lossless Transformer Reset - Magnetizing energy can be recycled Natural average ZVS switching (Zero Voltage current Switching) for Highest Efficiency ->50% Wider Duty input Cycle voltage range and higher turn ratio -Recycles Current Inductive stresses Energy on the primary side and voltage Reduced stresses EMI on the sec side can be reduced significantly Easy to Adapt Self-Driven Synchronous Rectification Switch Voltage is Clamped to Control Level, Disadvantages Resulting in Lower Stress Switching Device Additional MOSFET Switch Required for Active Reset Gate Drive Circuitry somewhat Complex - Precision Lower switching Max Duty losses Cycle Clamp is Critical - Advanced Higher frequency PWM Control operation Technique Required - Lower EMI/RFI ZVS of the Main Switching is Possible, Leading to Transformer Waveform Allows for Easy Implementation of Sync-Rectification on the Secondary Side. 25

26 Active Clamp Reset Technique (a) (b) (c) (d) 26

27 Why there is no ZVS when Main Switch turns-on? If the secondary side leakage is small the magnetizing energy necessary to turn D1 on will be diverted through D3 (Q3) during the reverse recovery of D4 (or Q4 reverse conduction) After the reverse recovery of D4, the magnetizing energy will continue discharging through the loop shown in blue Since there is no energy to turn D1 ON, ZVS of Q1 does not take place. 27

28 UCC2891/2/3/4/7 Active Clamp Controllers Product UCC2891 UCC2892 UCC2893 UCC2894 UCC2897 Control CMC CMC CMC CMC CMC Gate Drive (Sink/Source) ±2A TrueDrive ±2A TrueDrive ±2A TrueDrive ±2A TrueDrive ±2A TrueDrive HV Startup Circuit (110V) SYNC LINE Auxiliary Monitor Output (UV) - (UV,OV) (110V) (UV) - (UV,OV) (110V) (Bidir) CS1 Threshold CS2 Threshold Slope Comp Max. Osc. Freq. P-Ch 0.75V - 1MHz P-Ch 1.27V - 1MHz N-Ch 0.75V - 1MHz N-Ch 1.27V - 1MHz (UV,OV) P-Ch 0.5V 0.75V UCC3580 VMC +1A / -0.5A - - P-Ch or N-Ch 1MHz - - N/A 400kHz Performance / Efficiency: ±2-A TrueDrive Gate Drives Flexibility: Telecom bus compatible Built-in 110V Start-up Circuit Prog. Internal Slope Comp Bidirectional Oscillator Synchronization -40 C to +125 C Operation Protection: Incorporates 0.5V Cycle by Cycle Current Limit 0.75V Second Level Hiccup Mode Threshold Accurate Input Line UV and OV Protection Monitors 28

29 PWM Controllers (50W >1KW) Soft-Switching, ZVT, ZVS (Phase-Shifted Full-Bridge, Resonant, Active-Clamp Forward) Dual- Complementary Outputs (Push-Pull, Half-Bridge, Full Bridge, Current-Fed/Voltage-Fed Push-Pull, Two Independent Flybacks/Forwards) Secondary Side Control; Post Regulation (Forward, Buck, Synchronous Buck) General Purpose Single Ended PWM (Forward, Flyback, Buck, Boost, SEPIC, Cuk) Green-Mode PWM and Off-line Bias Regulators (Flyback, Forward, QR Flyback) UC w/ Drivers UC Resonant Mode Controllers UC3846 UC3856 UC3825 UC3524A UC3525A UC3526A UC3849 Avg.I-Mode w/ LS UC3824 UC UC3842A-5A UC3879 w/o Drivers UC3827 I/V-Fed P-P UCC3580 V-Mode Act-Clamp UC28025 UCC Independent Channels, 50%DC UCC3583 UC3854 SSPR UCC3839 Avg.I-Mode UCC UCC3813 4/5Vref, SS, LEB UCC3895 Adv. Φ-Shift UCC3806 UCC I-Mode Act- Clamp, HVStart UCC Slope Comp UCC3808/A 8-pin P-P UC3827 I/V-Fed P-P UCC3960/61 Primary Side Start-up UCC3807 UCC3809 Prog. Max DC UCC3888/89 Off-line Bias Regulators UC3825A/B UCC2897 Adv. I-Mode Act-Clamp, HVStart UCC28220/1 Interleaved Fwd/Flyback Prog MaxDC >50% UCC28089 Push-Pull Osc UCC2540 Sec. Side Sync- Buck, PGD UCC3580 SR Control UCC3884 Freq. Foldback, V*S Clamp UCC38C42-45 BiCMOS 3842A- 45A UCC3581 Micro Power Green PWM Voltage Mode Current Mode Resonant Mode UCC2541 UCC2541 Sec. Sec. Side Side Sync-Buck Sync-Buck w/ w/ Osc., Osc., PGD PGD UCC28600 UCC28600 QR QR Green Green Mode Mode PWM PWM Existing Products

30 AC-DC PFC Introduction & Design Considerations Isolated PWM Solutions Introduction DC-DC Buck Design Software Introduction

31 TPS5430/31 - High-Vin Non-Sync. Converter 5.5~36V (5.5~23V) Input Range; 8pin Power Pad SOIC Integrated 110mΩ Rds(on) High Side Switch for 3A Continuous Output Current Adjustable Output Voltages down to 1.22V with 1.5% Accuracy Internal Compensation Allows Lower External Part Count Internal Slow-start, Under-voltage Lockout, Current limit, Thermal shutdown and Enable Consumer: LCD-TV, PDP-TV, P-DVD Player, Car-TV, IP-STB, Video Phone Industrial: Point-of-Load Regulation for 3.3/5V Logic Telecom CPE Side and Automotive Power Supplies 5.5V~36V (5.5~23V) Input Voltage Range 110mΩ Rds(on) Continuous 3A Output Down to 1.22V & Reference with 1.5% Accuracy Voltage Feed Forward Internal Bootstrap Diode Switching Frequency Fsw: 500KHz Enable ON/OFF Control Internal Compensation & Slow Start 31

32 Design Tool (Software) Introduction Designer Software Tool: TI Web power.ti.com Design Software Includes: Completed Circuitry, Components Value and Database Power Specification & Key Parts Stress Analysis Loop Response & System Stability Analysis Efficiency Curve & Bill of Material PCB & Power PAD Layout Guideline TPS40K Design Software SWIFT Design Software 32

33 Link to TI Power Website: power.ti.com Web: power.ti.com Quick Search Selection Guides Product Information Download Software New Products 33

34 Thanks for Your Time! TI + Contract Manufacturer Support TI Customer Service Organization TI Field Applications Engineers TI Distributors Customer TI Manufacturing Reps TI Sales Engineers Factory Applications Website: power.ti.com