UCC28061 UCC2 8060 www.ti.com .............................................................................................................................................................. SLUS837A – JUNE 2008 – REVISED JULY 2009 Natural Interleaving™ Transition-Mode PFC Controller With Improved Audible Noise Immunity NATURAL INTERLEAVING FEATURES SYSTEM FEATURES • Phase Management Capability • FailSafe OVP with Dual Paths Prevents Output Over-Voltage Conditions Caused by Voltage-Sensing Failures • Sensorless Current Shaping Simplifies Board Layout and Improves Efficiency • Inrush Safe Current Limiting: – Prevents MOSFET conduction during inrush – Eliminates reverse recovery events in output rectifiers • • • • 1 23 400 VDC EMI Filter – + VCC 85-265VAC ZCDA GDA CS VINAC ZCDB UCC28061 GDB TSET PWMCNTL VSENSE COMP PHB • • • • • • Improved Audible Noise Performance Soft Start on Overvoltage Integrated Brownout Improved Efficiency and Design Flexibility over Traditional, Single-Phase Continuous Conduction Mode (CCM) Input Filter and Output Capacitor Current Cancellation: – Reduced current ripple for higher system reliability and smaller bulk capacitor – Reduced EMI filter size Enables Use of Low-Cost Diodes without Extensive Snubber Circuitry Improved Light-Load Efficiency Improved Transient Response Complete System-Level Protection 1-A Source/1.8-A Sink Gate Drivers APPLICATIONS Power Good to downstream converter VREF HVSEN • • • • • • 100-W to 800-W Power Supplies Gaming D to A Set Top Boxes Adapters LCD, Plasma and DLP™ TVs Home Audio Systems 5 Typical Application Circuit Capacitor Ripple Current (A) AGND PGND POUT = 600 W VOUT = 400 V 4 1-Phase TM 3 1-Phase CCM 2 2-Phase TM Interleave 1 70 120 170 220 270 Input Voltage (V) Ripple Current Reduction 1 2 3 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. DLP is a trademark of Texas Instruments. Natural Interleaving is a trademark of Texas Instuments. 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 © 2008–2009, Texas Instruments Incorporated UCC28061 SLUS837A – JUNE 2008 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com CONTENTS • • • • • • • • Ordering Information 2 Electrical Characteristics 4 Device Information 7 Functional Block Diagram 9 Typical Characteristics 10 Application Information 16 Design Example 22 Additional References 29 DESCRIPTION Optimized for consumer applications concerned with audible noise elimination, this solution extends the advantages of transition mode—high efficiency with low-cost components—to higher power ratings than previously possible. By utilizing a Natural Interleaving technique, both channels operate as masters (that is, there is no slave channel) synchronized to the same frequency. This approach delivers inherently strong matching, faster responses, and ensures that each channel operates in transition mode. Complete system-level protections feature input brownout, output over-voltage, open-loop, overload, soft-start, phase-fail detection, and thermal shutdown. The additional FailSafe over-voltage protection (OVP) feature protects against shorts to an intermediate voltage that, if undetected, could lead to catastrophic device failure. This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. ORDERING INFORMATION (1) (1) (2) 2 PART NUMBER PACKAGE (2) OPERATING TEMPERATURE RANGE, TA UCC28061D SOIC 16-Pin (D) –40°C to +125°C 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. SOIC (D) package is available taped and reeled by adding R to the above part number. Reeled quantities for UCC28061DR are 2500 devices per reel. Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 UCC28061 www.ti.com .............................................................................................................................................................. SLUS837A – JUNE 2008 – REVISED JULY 2009 ABSOLUTE MAXIMUM RATINGS (1) All voltages are with respect to GND, –40°C < TJ = TA < +125°C, and currents are positive into and negative out of the specified terminal, unless otherwise noted. UCC28061 Input voltage range VCC (2) –0.5 to +21 PWMCNTL –0.5 to +20 COMP (3), CS, PHB, HVSEN (4), VINAC (4), VSENSE (4) –0.5 to +7 ZCDA, ZCDB –0.5 to +4 Continuous input current VCC 20 Input current PWMCNTL 10 Input current range ZCDA, ZCDB, VSENSE Output current VREF –10 Continuous gate current GDA, GDB (5) ±25 Junction temperature, TJ Lead temperature, TSOL (1) (2) (3) (4) (5) UNIT V –5 to +5 mA Operating –40 to +125 Storage –65 to +150 Soldering, 10s °C +260 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 condition beyond those included under recommended operating conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods of time may affect device reliability. Voltage on VCC is internally clamped. VCC may exceed the absolute maximum input voltage if the source is current limited below the absolute maximum continuous VCC input current level. In normal use, COMP is connected to capacitors and resistors and is internally limited in voltage swing. In normal use, VINAC, VSENSE, and HVSEN are connected to resistors and are internally limited in voltage swing. Although not recommended for extended use, VINAC, VSENSE, and HVSEN can survive input currents as high as ±10 mA from high voltage sources. No GDA or GDB current limiting is required when driving a power MOSFET gate. However, a small series resistor may be required to damp ringing due to stray inductance. See Figure 12 and Figure 13 for details. DISSIPATION RATINGS (1) PACKAGE THERMAL IMPEDANCE JUNCTION-TO-AMBIENT TA = +25°C POWER RATING TA = +85°C POWER RATING SOIC 16-Pin (D) 140°C/W (1) 890 mW (1) 460 mW (1) Tested per JEDEC EIA/JESD 51-1. Thermal resistance is a strong function of board construction and layout. Air flow will reduce thermal resistance. This number is only a general guide; see TI document SPRA953 device Thermal Metrics. RECOMMENDED OPERATING CONDITIONS All voltages are with respect to GND, –40°C < TJ = TA < +125°C, and currents are positive into and negative out of the specified terminal, unless otherwise noted. MIN MAX VCC input voltage from a low-impedance source 14 21 VCC input current from a high-impedance source 8 18 VREF load current 0 –2 VINAC Input voltage 0 6 ZCDA, ZCDB series resistor TSET resistor to program PWM on-time HVSEN input voltage PWMCNTL pull-up resistor to VREF UNIT V mA V 20 80 66.5 400 0.8 4.5 V 1 10 kΩ kΩ ELECTROSTATIC DISCHARGE (ESD) PROTECTION RATING UNIT Human body model (HBM) 2000 V Charged device model (CDM) 500 V Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 3 UCC28061 SLUS837A – JUNE 2008 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com ELECTRICAL CHARACTERISTICS At VCC = 16 V, AGND = PGND = 0 V, VINAC = 3 V, VSENSE = 6 V, HVSEN = 3 V, PHB = 5 V, RTSET = 133 kΩ; all voltages are with respect to GND, all outputs unloaded, –40°C < TJ = TA < +125°C, and currents are positive into and negative out of the specified terminal, unless otherwise noted. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT VCC BIAS SUPPLY VCC(shunt) VCC shunt voltage (1) IVCC = 10 mA 24 26 V IVCC(stby) VCC current, disabled VSENSE = 0 V 100 200 µA IVCC(on) VCC current, enabled VSENSE = 6 V 5 8 mA 22 UNDERVOLTAGE LOCKOUT (UVLO) VCC(on) VCC turn-on threshold 11.5 12.6 13.5 VCC(off) VCC turn-off threshold 9.5 10.35 11.5 1.85 2.25 2.65 5.82 UVLO Hysteresis V REFERENCE VREF VREF output voltage, no load IVREF = 0 mA 6.00 6.18 VREF change with load 0 mA ≤ IVREF ≤ –2 mA 1 6 VREF change with VCC 12 V ≤ VCC ≤ 20 V 1 10 5.85 6.00 6.15 5.82 6.00 6.18 V mV ERROR AMPLIFIER VSENSE input regulation voltage TA = +25°C VSENSE input regulation voltage gm VOVP VSENSE input bias current In regulation 125 300 800 COMP high voltage, clamped VSENSE = 5.8 V 4.70 4.95 5.10 COMP low voltage, saturated VSENSE = 6.2 V 0.03 0.125 VSENSE to COMP transconductance COMP = 3 V, 5.94 V < VSENSE < 6.06 V 75 96 110 COMP source current, overdriven VSENSE = 5 V, COMP = 3 V –120 –160 –190 COMP sink current VSENSE = 6.2 V, COMP = 3 V 7 20 32 VSENSE threshold for COMP offset enable, down from VREF Voltage below VREF 135 185 235 6.7 VSENSE over-voltage threshold, rising 6.25 6.45 VSENSE over-voltage hysteresis 0.1 0.2 0.4 VSENSE enable threshold, rising 1.15 1.25 1.35 VSENSE enable hysteresis 0.02 0.05 0.2 2.50 2.65 V nA V µS µA mV V OUTPUT MONITORING VPWMCNTL (1) 4 HVSEN threshold to PWMCNTL HVSEN rising 2.35 HVSEN input bias current, high HVSEN = 3 V –0.5 HVSEN input bias current, low HVSEN = 2 V 28 36 HVSEN rising threshold to over-voltage fault 4.64 4.87 5.1 HVSEN falling threshold to over-voltage fault 4.45 4.67 4.80 8 12 20 ms 1 µA 0.2 0.5 V Phase Fail filter time to PWMCNTL high PHB = 5 V, ZCDA switching, ZCDB = 0.5 V PWMCNTL leakage current high HVSEN = 2 V, PWMCNTL = 15 V PWMCNTL output voltage low HVSENS = 3 V, IPWMCNTL = 5 mA 0.5 –1 41 V µA V Excessive VCC input voltage and current will damage the device. This clamp does not protect the device from an unregulated supply. If an unregulated supply is used, a Fixed Positive Voltage Regulator such as the UA78L15A is recommended. See the Absolute Maximum Ratings table for the limits on VCC voltage and current. Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 UCC28061 www.ti.com .............................................................................................................................................................. SLUS837A – JUNE 2008 – REVISED JULY 2009 ELECTRICAL CHARACTERISTICS (continued) At VCC = 16 V, AGND = PGND = 0 V, VINAC = 3 V, VSENSE = 6 V, HVSEN = 3 V, PHB = 5 V, RTSET = 133 kΩ; all voltages are with respect to GND, all outputs unloaded, –40°C < TJ = TA < +125°C, and currents are positive into and negative out of the specified terminal, unless otherwise noted. PARAMETER TEST CONDITIONS MIN TYP MAX 15 UNIT GATE DRIVE (2) GDA, GDB output voltage high IGDA, IGDB = –100 mA 11.5 13 GDA, GDB output voltage high, clamped VCC = 20 V, IGDA, IGDB = –5 mA 12 13.5 15 GDA, GDB output voltage high, low VCC VCC = 12 V, IGDA, IGDB = –5 mA 10 10.5 11.5 GDA, GDB on-resistance high IGDA, IGDB = –100 mA 8 14 GDA, GDB output voltage low IGDA, IGDB = 100 mA 0.15 0.3 V GDA, GDB on-resistance low IGDA, IGDB = 100 mA 2 3 Ω Rise time 1 V to 9 V, CLOAD = 1 nF 18 30 Fall time 9 V to 1 V, CLOAD = 1 nF 12 25 GDA, GDB output voltage UV IGDA, IGDB = 2.5 mA 1.6 2 V Ω ns V ZERO CURRENT DETECTOR ZCDA, ZCDB voltage threshold, falling 0.8 1.0 1.2 ZCDA, ZCDB voltage threshold, rising 1.5 1.68 1.88 3.0 3.4 ZCDA, ZCDB clamp, high IZCDA = +2 mA, IZCDB = +2 mA 2.6 ZCDA, ZCDB input bias current ZCDA = 1.4 V, ZCDB = 1.4 V –0.5 ZCDA, ZCDB clamp, low IZCDA = –2 mA, IZCDB = –2 mA –0.4 ZCDA, ZCDB delay to GDA, GDB outputs (2) Respective gate drive output rising 10% from zero crossing input falling to 1 V V 0.5 µA –0.2 0 V 45 100 ns µA CURRENT SENSE CS input bias current –150 –250 CS current limit rising threshold At rising threshold –0.18 –0.20 –0.22 CS current limit falling threshold –0.005 –0.015 –0.029 60 100 ns 0.5 µA V CS current limit response time (2) From CS exceeding threshold –0.05 V to GDx dropping 10% VINAC input bias current VINAC = 2 V –0.5 VINAC brownout threshold VINAC falling 1.34 1.39 1.44 V VINAC brownout current VINAC = 1 V 5 7 9 µA VINAC brownout filter time VINAC fails to exceed the brownout threshold for the brownout filter time 340 440 540 ms MAINS INPUT BROWNOUT (2) Refer to Figure 12, Figure 13, Figure 14, and Figure 15 in the Typical Characteristics for typical gate drive waveforms. Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 5 UCC28061 SLUS837A – JUNE 2008 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com ELECTRICAL CHARACTERISTICS (continued) At VCC = 16 V, AGND = PGND = 0 V, VINAC = 3 V, VSENSE = 6 V, HVSEN = 3 V, PHB = 5 V, RTSET = 133 kΩ; all voltages are with respect to GND, all outputs unloaded, –40°C < TJ = TA < +125°C, and currents are positive into and negative out of the specified terminal, unless otherwise noted. PARAMETER TEST CONDITIONS MIN TYP MAX UNIT PULSE-WIDTH MODULATOR KTL KTLS T(min) On-time factor, phases A and B VINAC = 3.2 V, VSENSE = 5.8 V (3) 3.6 4.0 4.4 On-time factor, single-phase, A VINAC = 3.2 V, VSENSE = 5.8 V, PHB = 0 V (3) 7.2 8 8.9 Phase B to phase A on-time matching VSENSE = 5.8 V, VINAC = 3.2 V –6% Zero-crossing distortion correction additional on time COMP = 0.25 V, VINAC = 1 V PHB threshold falling, to single-phase operation PHB threshold rising, to two-phase operation Minimum switching period RTSET = 133 kΩ (3) 1.7 2.2 2.5 PWM restart time ZCDA = ZCDB = 2 V (4) 165 200 265 6% 1.2 2 2.7 12.6 20 29 To GDB output shutdown VINAC = 1.5 V 0.7 0.8 0.9 To GDB output running VINAC = 1.5 V 0.9 1.0 1.1 COMP = 0.25 V, VINAC = 0.1 V µs/V µs V µs THERMAL SHUTDOWN (3) (4) (5) 6 Thermal shutdown temperature TJ, temperature rising (5) +160 Thermal restart temperature TJ, temperature falling (5) +140 °C Gate drive on-time is proportional to VCOMP – 125 mV. The on-time proportionality factor, KT, is different in two-phase and single-phase modes. The on-time factor, KT, scales linearly with the value of RTSET. The minimum switching period is proportional to RTSET. An output on-time is generated at both GDA and GDB if both ZCDA and ZCDB negative-going edges are not detected for the restart time. In single-phase mode, the restart time applies for the ZCDA input and the GDA output. Thermal shutdown occurs at temperatures higher than the normal operating range. Device performance above the normal operating temperature is not specified or assured. Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 UCC28061 www.ti.com .............................................................................................................................................................. SLUS837A – JUNE 2008 – REVISED JULY 2009 DEVICE INFORMATION UCC28061D SOIC 16-Pin (D) Top View ZCDB 1 16 ZCDA VSENSE 2 15 VREF TSET 3 14 GDA PHB 4 13 PGND COMP 5 12 VCC AGND 6 11 GDB VINAC 7 10 CS HVSEN 8 9 PWMCNTL TERMINAL FUNCTIONS TERMINAL DESCRIPTION NAME NO. I/O AGND 6 — Analog ground: Connect analog signal bypass capacitors, compensation components, and analog signal returns to this pin. Connect the analog and power grounds at a single point to isolate high-current noise signals of the power components from interference with the low-current analog circuits. O Error amplifier output: The error amplifier is a transconductance amplifier, so this output is a high-impedance current source. Connect voltage regulation loop compensation components from this pin to AGND. The on-time seen at the gate drive outputs is proportional to the voltage at this pin minus an offset of approximately 125 mV. During soft-start events (undervoltage, brownout, disable or output over voltage), COMP is pulled low. Normal operation only resumes after the soft-start event clears and COMP has been discharged below 0.5 V, making sure that the circuit restarts with a low COMP voltage and a short on-time. Do not connect COMP to a low-impedance source that would interfere with COMP falling below 0.5 V. Current sense input: Connect the current sense resistor and the negative terminal of the diode bridge to this pin. Connect the return of the current sense resistor to the AGND pin with a separate trace. As input current increases, the voltage on CS goes more negative. This cycle-by-cycle over-current protection limits input current by turning off both gate driver (GDx) outputs when CS is more negative than the CS rising threshold (approximately –200 mV). The GD outputs remain low until CS falls to the CS falling threshold (approximately –15 mV). Current sense is blanked for approximately 100 ns following the falling edge of either GD output. This blanking filters noise that occurs when current switches from a power FET to a boost diode. In most cases, no additional current sense filtering is required. If filtering is required, the filter series resistance must be under 100 Ω to maintain accuracy. To prevent excessive negative voltage on the CS pin during inrush conditions, connect the current sensing resistor to the CS pin through a low value external resistor. COMP 5 CS 10 I GDA 14 O GDB 11 O Channel A and channel B gate drive output: Connect these pins to the gate of the power FET for each phase through the shortest connection practical. If it is necessary to use a trace longer than 0.5 inch (12.6 mm) for this connection, some ringing may occur due to trace series inductance. This ringing can be reduced by adding a 5-Ω to 10-Ω resistor in series with GDA and GDB. High voltage output sense: The UCC28061 incorporates FailSafe OVP so that any single failure does not allow the output to boost above safe levels. Output over-voltage is monitored by both VSENSE and HVSEN and shuts down the PWM if either pin exceeds the appropriate over-voltage threshold. Using two pins to monitor for over-voltage provides redundant protection and fault tolerance. HVSEN can also be used to enable a downstream power converter when the voltage on HVSEN is within the operating region. Select the HVSEN divider ratio for the desired over-voltage and power-good thresholds. Select the HVSEN divider impedance for the desired power-good hysteresis. During operation, HVSEN must never fall below 0.8 V. Dropping HVSEN below 0.8 V puts the UCC28061 into a special test mode, used only for factory testing. A bypass capacitor from HVSEN to AGND is recommended to filter noise and prevent false over-voltage shutdown. HVSEN 8 I PGND 13 — Power ground for the integrated circuit: Connect this pin to AGND through a separate short trace to isolate gate driver noise from analog signals. I Phase B enable: This pin turns on/off channel B of the boost converter. The commanded on-time for channel A is immediately doubled when channel B is disabled, which helps to keep COMP voltage constant during the phase management transient. The PHB pin allows the user to add external phase management circuitry if they desire. To disable phase management, connect the PHB pin to the VREF pin. PHB 4 Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 7 UCC28061 SLUS837A – JUNE 2008 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com TERMINAL FUNCTIONS (continued) TERMINAL NO. I/O PWMCNTL 9 O PWM enable logic output: This open-drain output goes low when HVSEN is within the HVSEN good region and the ZCDA and ZCDB inputs are switching correctly if operating in two-phase mode (see PHB Pin). Otherwise, PWMCNTL is high impedance. TSET 3 I Timing set: PWM on-time programming input. Connect a resistor from TSET to AGND to set the on-time versus COMP voltage and the minimum period at the gate drive outputs. VCC 12 — Bias supply input: Connect this pin to a controlled bias supply of between 14 V and 21 V. Also connect a 0.1-µF ceramic bypass capacitor from this pin to PGND with the shortest possible board trace. This supply powers all circuits in the device and must be capable of delivering 6 mA dc plus the transient power MOSFET gate charging current. VINAC 7 I Input ac voltage sense: For normal operation, connect this pin to a voltage divider across the rectified input power mains. When the voltage on VINAC remains below the brownout threshold for more than the brownout filter time, the device enters a brownout mode and both output drives are disabled. Select the input voltage divider ratio for the desired brownout threshold. Select the divider impedance for the desired brownout hysteresis. VREF 15 O Voltage reference output: Connect a 0.1-µF ceramic bypass capacitor from this pin to AGND. VREF turns off during VCC undervoltage and VSENSE disable to save supply current and increase efficiency. This 6 VDC reference can be used to bias other circuits requiring less than 2 mA of total supply current. I Output dc voltage sense: Connect this pin to a voltage divider across the output of the power converter. The error amplifier reference voltage is 6 V. Select the output voltage divider ratio for the desired output voltage. Connect the ground side of this divider to ground through a separate short trace for best output regulation accuracy and noise immunity. VSENSE can be pulled low by an open-drain logic output or 6-V logic output in series with a low-leakage diode to disable the outputs and reduce VCC current. If VSENSE is disconnected, open-loop protection provides an internal current source to pull VSENSE low, turning off the gate drivers. I Zero current detection inputs: These inputs expect to see a negative edge when the inductor current in the respective phases go to zero. The inputs are clamped at 0 V and 3 V. Signals should be coupled through a series resistor that limits the clamping current to less than ±3 mA. Connect these pins through a current limiting resistor to the zero crossing detection windings of the appropriate boost I inductor. The inductor winding must be connected so that this voltage drops when inductor current decays to zero. When the inductor current drops to zero, the ZCD input must drop below the falling threshold, approximately 1 V, to cause the gate drive output to rise. When the power MOSFET turns off, the ZCD input must rise above the rising threshold, approximately 1.7 V, to arm the logic for another falling ZCD edge. VSENSE ZCDA ZCDB 8 DESCRIPTION NAME 2 16 1 Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 UCC28061 www.ti.com .............................................................................................................................................................. SLUS837A – JUNE 2008 – REVISED JULY 2009 BLOCK DIAGRAM Overcurrent CS HVSENOV OV TSD OC Burst Operation SinglePhase 10 OC -0.2V/-0.015V + 1.4V + 440ms Delay VINAC STOPA STOPB Brownout 7 Thermal ShutDown TJ 12.6V 10.35V + UV + TSD 160C 7mA 12 VCC 14 GDA 11 GDB 13 PGND 8 HVSEN 24V STOPA 13.5V Crossover Notch Reduction TSET 3 ZCDA 16 PGND Interleave Control ZCA 13.5V + 1.68V/1V ZCDB Phase A On Time Control Phase B On Time Control ZCB 1 + 1.68V/1V 222mV + STOPB VREF 6V 15 Brownout UV EN OV UV HVSEN OV + 4.87V EN + gm VSENSE + 2 0.8V 4.95V 96ms 2.5V + Single Phase EN 1.25V 36mA + Phase Fail Detector 6.45V OV Phase OK + 300nA 5 4 6 9 COMP PHB AGND PWMCNTL Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 9 UCC28061 SLUS837A – JUNE 2008 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com TYPICAL CHARACTERISTICS At VCC = 16 V, AGND = PGND = 0 V, VINAC = 3 V, VSENSE = 6 V, HVSEN = 3 V, PHB = 5 V, RTSET = 133 kΩ; all voltages are with respect to GND, all outputs unloaded, TJ = TA = +25°C, and currents are positive into and negative out of the specified terminal, unless otherwise noted. BIAS SUPPLY CURRENT vs BIAS SUPPLY VOLTAGE BIAS SUPPLY CURRENT vs TEMPERATURE 5.5 6.0 5.0 5.8 4.5 IVCC - Bias Supply Current - mA IVCC - Bias Supply Current - mA Operating 4.0 3.5 3.0 2.5 VCC Turn-Off VCC Turn-On 2.0 1.5 1.0 5.6 5.4 5.2 5.0 4.8 4.6 4.4 4.2 0.5 4.0 0 0 2 4 6 8 10 12 14 16 18 20 -40 -20 0 20 40 60 80 100 120 TJ - Temperature - °C VVCC - Bias Supply Voltage - V Figure 1. Figure 2. BIAS SUPPLY CURRENT vs TEMPERATURE ERROR AMPLIFIER TRANSFER FUNCTION 40 140 20 Transconductance 96 mS 0 ICOMP - Output Current - mA IVCC - Bias Supply Current - mA 120 100 80 60 40 20 -20 Input Regulation Voltage 0 mA at 6.0 V -40 -60 -80 COMP Offset Enable 165 mV Down from Regulation Voltage -100 -120 -140 -160 Disabled Source Current Overdriven -160 mA 0 -180 -40 -20 0 20 40 60 80 100 120 5.5 TJ - Temperature - °C 5.6 5.7 5.8 5.9 6.0 6.1 6.2 6.3 6.4 6.5 VVSENSE - Input Voltage - V Figure 4. Figure 3. 10 Sink Current 25 mA Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 UCC28061 www.ti.com .............................................................................................................................................................. SLUS837A – JUNE 2008 – REVISED JULY 2009 TYPICAL CHARACTERISTICS (continued) At VCC = 16 V, AGND = PGND = 0 V, VINAC = 3 V, VSENSE = 6 V, HVSEN = 3 V, PHB = 5 V, RTSET = 133 kΩ; all voltages are with respect to GND, all outputs unloaded, TJ = TA = +25°C, and currents are positive into and negative out of the specified terminal, unless otherwise noted. ERROR AMPLIFIER TRANSCONDUCTANCE vs TEMPERATURE ERROR AMPLIFIER OUTPUT CURRENT vs OUTPUT VOLTAGE 11 110 5.94 V < VSENSE < 6.06 V 10 9 ICOMP - Output Current - mA gm - Transconductance - ms 105 100 95 90 8 7 6 5 4 3 2 85 1 VSENSE = 6.1 V 80 0 -40 -20 0 20 40 60 80 100 120 0 1 TJ - Temperature - °C Figure 5. ERROR AMPLIFIER INPUT BIAS CURRENT vs INPUT VOLTAGE 3 4 5 CURRENT SENSE INPUT BIAS CURRENT vs TEMPERATURE 150 ICS - Current Sense Input Bias Current - mA 440 400 IVSENSE - Input BiasCurrent - nA 2 VCOMP - Output Voltage - V Figure 6. 360 320 280 240 200 160 120 80 40 145 140 135 130 125 0 0 0.6 1.2 1.8 2.4 3.0 3.6 4.2 4.8 5.4 6.0 -40 VVSENSE - Input Voltage - V Figure 7. -20 0 20 40 60 80 100 120 TJ - Temperature - °C Figure 8. Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 11 UCC28061 SLUS837A – JUNE 2008 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com TYPICAL CHARACTERISTICS (continued) At VCC = 16 V, AGND = PGND = 0 V, VINAC = 3 V, VSENSE = 6 V, HVSEN = 3 V, PHB = 5 V, RTSET = 133 kΩ; all voltages are with respect to GND, all outputs unloaded, TJ = TA = +25°C, and currents are positive into and negative out of the specified terminal, unless otherwise noted. ZERO CURRENT DETECT CLAMP CURRENT vs HIGH INPUT VOLTAGE ZERO CURRENT DETECT CLAMP CURRENT vs LOW INPUT VOLTAGE 5 0 -0.5 IZCD - Clamp Current - mA IZCD - Clamp Current - mA 4 3 2 -1.0 -1.5 -2.0 -2.5 1 -3.0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 -3.5 -0.4 4.0 -0.3 BROWNOUT FILTER DELAY TIME vs TEMPERATURE 0.2 0.3 0.4 GATE DRIVE RISING vs TIME 500 14 3.0 VCC = 20 V and 12 V CLOAD = 4.7 nF 490 12 480 2.5 470 10 460 Gate Drive Output - V Brownout Filter Delay Time - ms 0.1 VZCD - Input Voltage - V Figure 10. Figure 9. 450 440 430 420 410 400 390 2.0 GD Voltage: VCC = 20 V VCC = 12 V 8 GD Source Current: VCC = 20 V VCC = 12 V 6 1.5 1.0 4 0.5 2 0 0 -0.5 380 370 360 350 -2 -1.0 0 -40 -20 0 20 40 60 80 100 50 120 TJ - Temperature - °C Figure 11. 12 0 -0.2 -0.1 VZCD - Input Voltage - V Gate Drive Source Current - A 0 100 150 200 250 300 350 Time - ns Figure 12. Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 UCC28061 www.ti.com .............................................................................................................................................................. SLUS837A – JUNE 2008 – REVISED JULY 2009 TYPICAL CHARACTERISTICS (continued) At VCC = 16 V, AGND = PGND = 0 V, VINAC = 3 V, VSENSE = 6 V, HVSEN = 3 V, PHB = 5 V, RTSET = 133 kΩ; all voltages are with respect to GND, all outputs unloaded, TJ = TA = +25°C, and currents are positive into and negative out of the specified terminal, unless otherwise noted. GATE DRIVE FALLING vs TIME GATE DRIVE RISING vs TIME AND DELAY FROM ZCD INPUT 10 8 1.5 6 1.0 4 0.5 2 0 GD Voltage: VCC = 20 V VCC = 12 V 0 6 2.5 2.0 GD Sink Current: VCC = 20 V VCC = 12 V 40 5 10 GD Output: TJ = -40°C TJ = +25°C TJ = +125°C 4 3 6 2 4 1 2 0 60 80 100 120 -1 140 -2 50 -25 0 100 Time - ns Figure 13. 300 RLOAD = 2.7 kW 12 300 10 200 8 6 GD Output: TJ = -40°C TJ = +25°C TJ = +125°C 4 -100 2 -200 0 -300 -2 14 Gate Drive Voltage - V 400 Gate Drive Output - V Current Sense Input - mV 250 15 14 CLOAD = 4.7 nF 0 200 GATE DRIVE OUTPUT HIGH vs VCC 500 CS Input Voltage 150 Time - ns Figure 14. GATE DRIVE FALLING vs TIME AND DELAY FROM CS INPUT 100 8 ZCD Input Voltage -1.0 20 12 0 -0.5 -2 0 14 CLOAD = 4.7 nF Gate Drive Source Current - A ZCD Input - V 12 Gate Drive Output - V 7 3.0 VCC = 20 V and 12 V CLOAD = 4.7 nF Gate Drive Output - V 14 TJ = -40°C 13 TJ = +25°C TJ = +125°C 12 11 10 9 -25 0 50 100 150 200 Time - ns 250 300 8 10 11 12 13 14 15 16 17 18 19 20 VVCC - Bias Supply Voltage - V Figure 16. Figure 15. Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 13 UCC28061 SLUS837A – JUNE 2008 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com TYPICAL CHARACTERISTICS (continued) At VCC = 16 V, AGND = PGND = 0 V, VINAC = 3 V, VSENSE = 6 V, HVSEN = 3 V, PHB = 5 V, RTSET = 133 kΩ; all voltages are with respect to GND, all outputs unloaded, TJ = TA = +25°C, and currents are positive into and negative out of the specified terminal, unless otherwise noted. GATE DRIVE OUTPUT IN UVLO vs SINK CURRENT GATE DRIVE HIGH VOLTAGE vs TEMPERATURE 2.5 15 14 13 TJ = -40°C Gate Drive Voltage - V Gate Drive Voltage - V 2.0 1.5 TJ = +25°C 1.0 TJ = +125°C 0.5 Clamped VCC ³ 15 V 12 11 Unclamped VCC = 12 V 10 9 8 7 6 RLOAD = 2 kW 0 5 0 1 2 3 4 5 6 7 8 9 10 -40 -20 0 ON-TIME FACTOR vs TIME SETTING RESISTOR 10 9 9 8 60 60 100 120 RTSET = 266 kW KTL 7 6 5 4 3 2 KTL - On-Time Factor - ms/V KT - On-Time Factor - ms/V 40 ON-TIME FACTOR PHASE A AND B vs TEMPERATURE 8 7 6 5 RTSET = 133 kW 4 3 2 RTSET = 66 kW 1 1 0 0 60 80 100 120 140 160 180 200 220 240 260 280 -40 RTSET - Time Setting Resistor - kW Figure 19. 14 20 TJ - Temperature - °C Figure 18. Gate Drive Sink Current - mA Figure 17. Submit Documentation Feedback -20 0 20 40 60 80 100 120 TJ - Temperature - °C Figure 20. Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 UCC28061 www.ti.com .............................................................................................................................................................. SLUS837A – JUNE 2008 – REVISED JULY 2009 TYPICAL CHARACTERISTICS (continued) At VCC = 16 V, AGND = PGND = 0 V, VINAC = 3 V, VSENSE = 6 V, HVSEN = 3 V, PHB = 5 V, RTSET = 133 kΩ; all voltages are with respect to GND, all outputs unloaded, TJ = TA = +25°C, and currents are positive into and negative out of the specified terminal, unless otherwise noted. ON-TIME FACTOR vs PHASE SHIFT PWM RESTART TIME vs TEMPERATURE 300 110 GDA 108 GDB RTSET = 266 kW 275 RTSET = 133 kW 106 KT/KT0 - % PWM Restart Time - ms 250 104 RTSET = 66 kW 102 100 98 96 225 200 175 150 94 KT0 = 92 2(KTA ´ KTB) 125 KTA + KTB 100 90 150 160 170 180 190 200 -40 210 -20 0 20 40 60 80 100 120 TJ - Temperature - °C Figure 22. Phase Shift of GDA Relative to GDB - Degrees Figure 21. ADDITIONAL ON-TIME vs VINAC ZERO-CROSSING DISTORTION CORRECTION 100 RTSET = 266 kW Additional On-Time - ms RTSET = 133 kW RTSET = 66 kW 10 1 0.1 0 0.5 1.0 1.5 2.0 2.5 3.0 VVINAC - Input AC Voltage Sense - V Figure 23. Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 15 UCC28061 SLUS837A – JUNE 2008 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com APPLICATION INFORMATION Theory of Operation The UCC28061 contains the control circuits for two boost pulse-width modulation (PWM) power converters. The boost PWM power converters ramp current in the boost inductors for a time period proportional to the voltage on the error amplifier output. Each power converter then turns off the power MOSFET until current in the boost inductor decays to 0, as sensed on the zero current detection inputs (ZCDA and ZCDB). Once the inductor current decays to 0, the power converter starts another cycle. This on/off cycling produces a triangle wave of current, with peak current set by the on-time and power mains input voltage, as shown in Equation 1. VINAC (t) ´ TON IPEAK (t) = L (1) The average line current is exactly equal to half of the peak line current, as shown in Equation 2. VINAC (t) ´ TON IAVG (t) = 2´L (2) With TON and L being essentially constant during an ac line period, the resulting triangular current waveform during each switching cycle has an average value proportional to the instantaneous value of the rectified ac line voltage. This architecture results in a resistive input impedance characteristic at the line frequency and a near-unity power factor. The outputs of the two PWMs operate 180° out-of-phase so that power-line ripple current for the two PWMs is greatly reduced from the ripple current of each individual PWM. This design reduces ripple current at the input and output, allowing the reduction in size and cost of input and output filters. Optimal phase balance occurs if the individual power stages and the on-times are well-matched. Mismatches in inductor values do not affect the phase relationship. On-Time Control, Maximum Frequency Limiting, and Restart Timer Gate drive on-time varies with the error amplifier output voltage by a factor called KT, as shown in Equation 3. TON = KT (VCOMP - 125 mV) (3) Where: VCOMP is the output of the error amplifier, and 125 mV is a modulator offset. To provide smooth transition between two-phase and single-phase operation, KT increases by a factor of two in single-phase mode: • KTLS = 2 × KTL; active in single-phase operation The clamped maximum output of the error amplifier is limited to 4.95 V. This value, less the 125 mV modulator offset, limits on-time to Equation 4. TON(max) = KT ´ 4.825 V (4) This on-time limit sets the maximum power that can be delivered by the converter at a given input voltage level. The switching frequency of each phase is limited by minimum period timers. If the current decays to 0 before the minimum period timer elapses, turn-on is delayed, resulting in discontinuous phase current. The restart timer ensures starting under all circumstances by restarting both phases if either phase ZCD input has not transitioned high-to-low for approximately 200 µs. To prevent the circuit from operating in continuous conduction mode (CCM), the restart time does not trigger turn-on until both phase currents return to 0. 16 Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 UCC28061 www.ti.com .............................................................................................................................................................. SLUS837A – JUNE 2008 – REVISED JULY 2009 The on-time factors (KTH, KTHS, KTL, KTLS) and the minimum switching period TMIN are proportional to the time setting resistor RTSET, the resistor from the TSET pin to ground, and they can be calculated by Equation 5 through Equation 6: ms RTSET KTL = ´ 4.0 V 133 kW (5) RTSET TMIN = ´ 2.2ms; Minimum Switching Period 133 kW (6) The proper value of RTSET results in the clamped maximum on-time, TON(max), required by the converter operating at the minimum input line and maximum load. Natural Interleaving Under normal operating conditions, the UCC28061 regulates the relative phasing of the channel A and channel B inductor currents to be very close to 180°, minimizing the ripple currents seen at the line source and output capacitor. The phase control function differentially modulates the on-times of the A and B channels based on the phase and frequency relationship. This natural interleaving method allows the converter to achieve 180° phase shift and transition mode operation for both phases without the requirements on boost inductor tolerance. As a result, the current sharing of the A and B channels are proportional to the inductor tolerance. The best current sharing is achieved when both inductors are exactly the same value. Phase Management At light load, it can improve efficiency to shut down one phase. Although conduction losses increase in one-phase operation, switching losses decrease. At certain power levels, the reduction of switching losses is greater than the increase in conduction losses. Turning off one phase at light load is especially valuable for meeting light-load efficient standards. To operate in two-phase (normal) mode, pull PHB high or connect PHB to VREF. To operate in one-phase mode, connect PHB to ground. Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 17 UCC28061 SLUS837A – JUNE 2008 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com Zero Crossing Detection and Valley Switching In transition-mode PFC circuits, the MOSFET turns on when the boost inductor current crosses 0. Because of the resonance between the boost inductor and the parasitic capacitor at the MOSFET drain node, part of the energy stored in the MOSFET junction capacitor can be recovered, reducing switching losses. Furthermore, when the rectified input voltage is less than half of the output voltage, all the energy stored in the MOSFET junction capacitor can be recovered and zero-voltage switching (ZVS) can be realized. By adding an appropriate delay, the MOSFET can be turned on at the valley of its resonating drain voltage (valley switching). In this way, the energy recovery can be maximized and switching loss is minimized. The RC time constant is generally derived empirically, but a good starting point is a value equal to 25% of the resonant period of the drain circuit. The delay can be realized by a simple RC filter, as shown in Figure 24. Because the ZCD pin is internally clamped, a more accurate delay can also be realized by using Figure 25. R R1 ZCD ZCD CT C CT Figure 24. Simple RC Delay Circuit C R2 Figure 25. More Accurate Time Delay Circuit Brownout Protection As the power line RMS voltage decreases, RMS input current increases to maintain the output voltage constant for a specific load. Brownout protection prevents the RMS input current from exceeding a safe operating level. Power line RMS voltage is sensed at VINAC. When the voltage applied to VINAC fails to exceed the brownout threshold for the brownout filter time, a brownout condition is detected and both gate drive outputs immediately pull low. During brownout, COMP is actively pulled low. Gate drive outputs remain low until the voltage on VINAC rises above the brownout threshold. After a brownout, the power stage soft-starts as COMP rises. The brownout detection threshold and its hysteresis are set by the voltage divider ratio and resistor values. Brownout protection is based on VINAC peak voltage; the threshold and hysteresis are also based on line peak voltage. The peak VINAC voltage can be easily translated into RMS value. Suggested resistor values for the voltage divider are 3 MΩ ±1% from the rectified input voltage to VINAC and 46.4 kΩ ±1% from VINAC to ground. These resistors set the typical thresholds for RMS line voltages, as shown in Table 1. Table 1. Brownout Thresholds THRESHOLD BROWNOUT (RMS) Falling 65 V Rising 79.8 V Failsafe OVP—Output Over-Voltage Protection FailSafe OVP prevents any single failure from allowing the output to boost above safe levels. Redundant paths for output voltage sensing provide additional protection against output over-voltage. Over-voltage protection is implemented through two independent paths: VSENSE and HVSEN. The converter shuts down if either input senses an over-voltage condition. The output voltage can still maintain a safe level with either loop failure. The device is re-enabled when both sense inputs fall back into the normal range. At that time, the gate drive outputs resume switching under PWM control. Output over-voltage does not cause soft-start and the COMP pin is not discharged during an output over-voltage event. 18 Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 UCC28061 www.ti.com .............................................................................................................................................................. SLUS837A – JUNE 2008 – REVISED JULY 2009 Over-Current Protection Under certain conditions (such as inrush, brownout recovery, and output overload), the PFC power stage sees large currents. It is critical that the power devices be protected from switching during these conditions. The conventional current sensing method uses a shunt resistor in series with the MOSFET source to sense the converter current, resulting in multiple ground points and high power dissipation. Furthermore, since no current information is available when the MOSFETs are off, the source resistor current sensing method requires repeated turn-ons of the MOSFETs during over-current conditions. As a result, the converter may temporarily operate in continuous current mode (CCM) and experience failures induced by excessive reverse recovery currents in the boost diode. The UCC28061 uses a single resistor to continuously sense the total inductor (input) current. This way, turn-on of the MOSFETs is completely avoided when the inductor currents are excessive. The drive to the MOSFETs is inhibited until total inductor current drops to near zero, precluding reverse recovery induced failures (these failures are most likely to occur when the ac line recovers from a brownout condition). Following an over-current condition, both MOSFETs are turned on in phase when the input current drops to near 0. Because two phase currents are temporarily operating in phase, set the over-current protection threshold to more than twice of each phase maximum current ripple value in order to allow a return to normal operation after an over-current event. Phase Fail Protection The UCC28061 detects failure of one phase by monitoring the sequence of ZCD pulses. During normal two-phase operation, if one ZCD input remains idle for longer than approximately 14 ms while the other ZCD input switches normally, PWMCNTL goes high, indicating that the power stage is not operating correctly. During normal single-phase operation, phase failure is not monitored. On the UCC28061, phase failure is not monitored if COMP is below approximately 222 mV. Distortion Reduction Because of the resonance between the capacitance present across the drain-source of the switching MOSFET and the boost inductor, conventional transition mode power factor correction circuits may not be able to absorb power from the input line when the input voltage is around 0 V. This limitation results in waveform distortion and increased harmonic distortion. To reduce line current distortion to the lowest possible level, the UCC28061 increases switching MOSFET on-time when input voltage is around 0 V to increase the power absorption and compensate for this effect. Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 19 UCC28061 SLUS837A – JUNE 2008 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com Improved Error Amplifier The voltage error amplifier is a transconductance amplifier. Voltage loop compensation is connected from the error amplifier output, COMP, to analog ground, AGND. The recommended compensation network is shown in Figure 26. REF COMP + VSENSE CZ CP 4.95 V RZ Figure 26. Typical Error Amplifier Compensation To improve the transient response, the error amplifier output current is increased by 100 µA when the error amp input is below 5.8 V, as shown in Figure 27. This increase allows faster charging of the compensation components following sudden load current increases (also refer to Figure 4 in the Typical Characteristics). 100mA OV PWM Shutdown + 6.45V + 5.8V VSENSE +g 6V m COMP Soft Start 0.5V + Brownout UV EN OV R Q S Q Figure 27. Error Amplifier Block Diagram Showing Speed-Up and Latched Soft-Start The UCC28061 asserts soft start when output over-voltage is detected, pulling COMP to ground. This improves response to a change from heavy load to light load. 20 Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 UCC28061 www.ti.com .............................................................................................................................................................. SLUS837A – JUNE 2008 – REVISED JULY 2009 Open-Loop Protection If the feedback loop is disconnected from the device, a current source internal to the UCC28061 pulls the VSENSE pin voltage towards ground. When VSENSE falls below 1.20 V, the device is disabled. When disabled, supply current decreases, and both gate drive outputs and COMP are actively pulled low. The device is re-enabled when VSENSE rises above 1.25 V. At that time, the gate drive outputs begin switching under PWM control. The device can be externally disabled by grounding the VSENSE pin with an open-drain or open-collector driver. When disabled, device supply current drops and COMP is actively pulled low. When VSENSE is released, the device soft-starts. This disable method forces the device into standby mode and minimizes its power consumption. This feature is particularly useful when standby power is a key design aspect. If the feedback loop is disconnected from ground, the VSENSE voltage goes high. When VSENSE rises above the over-voltage protection threshold, both gate drive outputs go low, and COMP is actively pulled low. The device is re-enabled when VSENSE falls back into range. At that time, the gate drive outputs begin switching under PWM control. The VSENSE pin is internally clamped to protect the device from damage under this condition. Soft-Start The PWM gradually ramps from zero on-time to normal on-time as the compensation capacitor from COMP to AGND charges from a low level to the final value. This process implements a soft-start, with a time constant set by the output current of the error amplifier and the value of the compensation capacitors. In the event of a brownout, logic disable, or VCC undervoltage fault, COMP is actively pulled low so the PWM soft-starts after this event is cleared. The UCC28061 also asserts soft start when output over-voltage is detected. Even if a fault event happens very briefly, soft-start fully discharges the compensation components before resuming operation, ensuring soft-starting. See Figure 27 for details. Light-Load Operation As load current decreases, the error amplifier commands less input current by lowering the COMP voltage. If PHB (normally connected to COMP) falls below 0.8 V at low input line (or 1.1 V at high input line), channel B stops switching and channel A on-time doubles to compensate. If COMP falls below 150 mV, channel A also stops switching and the loop enters a hysteretic control mode. The PWM skips cycles to maintain regulation. Instead of skipping cycles, the UCC28061 allows on-time reduction smoothly to zero as load decreases. However, maximum switching frequency is limited, so at very light load, discountinuous operation is possible. Command for the Downstream Converter In the UCC28061, the PWMCNTL pin is used to coordinate the PFC stage with a downstream converter. Through the HVSEN pin, the output voltage is sensed. When the output voltage is within the desired range, the PWMCNTL pin is pulled to ground internally and can be used to enable a downstream converter. The enable threshold and hysteresis can be adjusted independently through the voltage divider ratio and resistor values. The HVSEN pin is also used for the FailSafe over-voltage protection. When designing the voltage divider, make sure this FailSafe over-voltage protection level is set above normal operating levels. VCC Undervoltage Protection VCC must rise above the undervoltage threshold for the PWM to begin functioning. If VCC drops below the threshold during operation, both gate drive outputs and COMP are actively pulled low. VCC must rise above the threshold for PWM function to restart. VCC VCC is connected to a bias supply of between 13 V and 21 V. When powered from a poorly-regulated supply, an external zener diode is recommended to prevent excessive current into VCC. Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 21 UCC28061 SLUS837A – JUNE 2008 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com DESIGN EXAMPLE An example of the UCC28061 PFC controller in a two-phase transition mode interleaved PFC pre-regulator is shown in Figure 28. Bridge F1 – + D3 16V CIN CF4 L1 CA 2.2 mF 22 pF RZA VCC ZCDA CS GDA 10 nF COMP ZCDB 22 pF COUT RG2 Q2 5W HVSEN CB RT CP RLOAD RA VINAC GDB VSENSE 2.2 mF CZ RC D2 16 V 50 kW VREF L2 20 kW TSET PWMCNTL RZ Q1 5W RZB PWMCNTL RP PHB RG1 20 kW CF5 UCC28061 RS VOUT D1 R 100 W RF AGND PGND CF2 RB CF3 RD RE Figure 28. Typical Transition Mode Interleaved PFC Pre-Regulator Design Goals The specifications for this design were chosen based on the power requirements of a 300-W LCD TV. These specifications are shown in Table 2. Table 2. Design Specifications PARAMETER MIN TYP VIN RMS input voltage 85 (VIN_MIN) VOUT Output voltage fLINE Line frequency PF Power factor at maximum load 0.90 η Full load efficiency 0.92 fMIN Minimum switching frequency UNIT 265 (VIN_MAX) VRMS 390 47 POUT 22 MAX 45 Submit Documentation Feedback V 63 Hz 300 W kHz Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 UCC28061 www.ti.com .............................................................................................................................................................. SLUS837A – JUNE 2008 – REVISED JULY 2009 Recommended PCB Device Layout CF4 Interleaved transition-mode PFC system architecture dramatically reduces input and output ripple current, allowing the circuit to use smaller and less expensive filters. To maximize the benefits of interleaving, the input and output filter capacitors should be located after the two phase currents are combined together. Similar to other power management devices, when laying out the printed circuit board (PCB) it is important to use star grounding techniques and keep filter capacitors as close to device ground as possible. To minimize the interference caused by capacitive coupling from the boost inductor, the device should be located at least 1 in (25.4 mm) away from the boost inductor. It is also recommended that the device not be placed underneath magnetic elements. Because of the precise timing requirement, the timing setting resistor RT should be put as close as possible to the TSET pin and returned to the analog ground. See Figure 29 for a recommended component layout and placement. Figure 29. Recommended PCB Layout NOTE: PHB and VREF Pins are connected by a Jumper on the back of the board. Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 23 UCC28061 SLUS837A – JUNE 2008 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com Inductor Selection The boost inductor is selected based on the inductor ripple current requirements at the peak of low line. Selecting the inductor requires calculating the boost converter duty cycle at the peak of low line (DPEAK_LOW_LINE), as shown in Equation 7. VOUT - VIN_MIN Ö2 390 V - 85 V Ö2 DPEAK_LOW_LINE = = » 0.69 VOUT 390 V (7) The minimum switching frequency of the converter (fMIN) under low line conditions occurs at the peak of low line and is set between 25 kHz and 50 kHz to avoid audible noise. For this design example, fMIN was set to 45 kHz: h ´ VIN_MIN2 x DPEAK_LOW_LINE 0.92(85 V)2 0.69 L1 = L2 = = » 340 mH POUT ´ fMIN 300 W ´ 45 kHz (8) The inductor for this design would have a peak current (ILPEAK) of 5.4 A, as shown in Equation 9, and an RMS current (ILRMS) of 2.2 A, as shown in Equation 10. 300 W Ö2 POUT Ö2 ILPEAK = = » 5.4 A VIN_MIN ´ h 85 V ´ 0.92 (9) ILRMS = ILPEAK Ö6 = 5.4 A » 2.2 A Ö6 (10) This converter uses constant on-time (TON) and zero-current switching (ZCS) to set up the converter timing. Auxiliary windings off of L1 and L2 detect when the inductor currents are 0. Selecting the turns ratio in Equation 11 ensures that there is at least 2 V at the peak of high line to reset the ZCD comparator after every switching cycle. The turns-ratio of each auxiliary winding is: VOUT - VIN_MAX Ö2 NP 390 V - 265 V Ö2 = = »8 2V 2V NS (11) ZCD Resistor Selection (RZA, RZB) The minimum value of the ZCD resistors is selected based on the internal zener clamp maximum current rating of 3 mA, as shown in Equation 12. VOUT NS 390 V RZA = RZB ³ = » 16.3 kW NP ´ 3 mA 8 ´ 3 mA (12) In this design the ZCD resistors were set to 20 kΩ, as shown in Equation 13. RZA = RZB = 20 kW 24 Submit Documentation Feedback (13) Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 UCC28061 www.ti.com .............................................................................................................................................................. SLUS837A – JUNE 2008 – REVISED JULY 2009 HVSENSE The HVSENSE pin programs the PWMCNTL output of the UCC28061. The PWMCNTL open-drain output can be used to disable a downstream converter while the PFC output capacitor is charging. PWMCNTL starts in high impedance and pulls to ground when the HVSENSE increases above 2.5 V. Setting the point where PWMCNTL becomes active requires a voltage divider from the boost voltage to the HVSEN pin to ground. Equation 14 to Equation 18 show how to set the PWMCNTL pin to activate when the output voltage is within 90% of its nominal value. VOUT_OK = VOUT ´ 0.90 » 351 V (14) Resistor RE sets up the high side of the voltage divider and programs the hysteresis of the PWMCNTL signal. For this example, RE was selected to provide 108 V of hysteresis, as shown in Equation 15. Hysteresis 108 V RE = = = 3 MW 36 mA 36 mA (15) Resistor RF is used to program the PWMCNTL active threshold, as shown in Equation 16. RF = 2.5 V VOUT_OK - 2.5 V RE = - 36 mA 2.5 V = 31.185 kW » 31.6 kW 351 V - 2.5 V - 36 mA 3 MW (16) This PWMCNTRL output remains active until a minimum output voltage (VOUT_MIN) is reached, as shown in Equation 17. 2.5 V (RE + RF) 2.5 V (3 MW + 31.6 kW) VOUT_MIN = = » 240 V 31.6 kW RF (17) According to the resistor value, the FailSafe OVP threshold should be set according to Equation 18: 4.87 V (RE + RF) 4.87 V (3 MW + 31.6 kW) VOV_FAILSAFE = = » 467 V 31.6 kW RF Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 (18) 25 UCC28061 SLUS837A – JUNE 2008 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com Output Capacitor Selection The output capacitor (COUT) is selected based on holdup requirements as shown in Equation 19. POUT 1 300 W 1 2 h 2 fLINE 0.92 47 Hz COUT ³ = » 147 mF 2 2 2 2 VOUT - (VOUT_MIN) (390 V) - (240 V) (19) Two 100-µF capacitors were used in parallel for the output capacitor: COUT = 200 mF (20) For this size capacitor, the output voltage ripple (VRIPPLE) is approximately 11 V, as shown in Equation 21: VRIPPLE = 2 ´ POUT 1 2 ´ 300 W = » 14V h VOUT ´ 4 p ´ fLINE ´ COUT 0.92 ´ 390V ´ 4 p ´ 47 Hz ´ 200 m F (21) In addition to hold-up requirements, a capacitor must be selected so that it can withstand the low-frequency RMS current (ICOUT_100 Hz) and the high-frequency RMS current (ICOUT_HF); see Equation 22 to Equation 24. High-voltage electrolytic capacitors generally have both a low- and a high-frequency RMS current rating on the product data sheets. POUT 300 W ICOUT_100Hz = = = 0.591 A 390 V ´ 0.92 ´ Ö2 VOUT ´ h ´ Ö2 (22) 2 ICOUT_HF = POUT 2 Ö2 4 Ö2 VIN_MIN 2 ´ h ´ VIN_MIN 9p VOUT - (ICOUT_100 Hz)2 (23) 2 ICOUT_HF = 300 W ´ 2 Ö2 2 ´ 0.92 ´ 85 V 4 Ö2 ´ 85 V 9p ´ 390 V - (0.591 A)2 » 0.966 A (24) 26 Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 UCC28061 www.ti.com .............................................................................................................................................................. SLUS837A – JUNE 2008 – REVISED JULY 2009 Selecting an RS for Peak Current Limiting The UCC28061 peak limit comparator senses the total input current and is used to protect the MOSFETs during inrush and over-load conditions. For reliability, the peak current limit (IPEAK) threshold in this design is set for 120% of the nominal inrush current that is observed during power-up, as shown in Equation 25. 2POUT Ö2 (1.2) 2 ´ 300 W Ö2 ´ 1.2 = IPEAK = » 13 A h ´ VIN_MIN 0.92 ´ 85 V (25) A standard 15-mΩ metal-film current-sense resistor is used for current sensing, as shown in Equation 26. The estimated power loss of the current sense resistor (PRS) is less than 0.25 W during normal operation, as shown in Equation 27. 200 mV 200 mV RS = = » 15 mW IPEAK 13 A (26) PRS = 2 POUT VIN_MIN ´ h 2 RS = 300 W 85 V ´ 0.92 ´ 15 mW » 0.22 W (27) The most critical parameter in selecting a current-sense resistor is the surge rating. The resistor needs to withstand a short-circuit current larger than the current required to open the fuse (F1). I2t (ampere squared seconds) is a measure of thermal energy resulting from current flow required to melt the fuse, where I2t is equal to RMS current squared times the duration of the current flow in seconds. A 4-A fuse with an I2t of 14 A2s was chosen to protect the design from a short-circuit condition. To ensure the current-sense resistors have a high enough surge protection, a 15-MΩ, 500-mW, metal-strip resistor was chosen for the design. The resistor has a 2.5-W surge rating for 5 seconds. This result translates into 833 A2s and has a high enough I2t rating to survive a short-circuit before the fuse opens, as described in Equation 28. 2.5 W I2t = ´ 5 s = 833 A2s 0.015 W (28) Power Semiconductor Selection (Q1, Q2, D1, D2): The selection of Q1, Q2, D1, and D2 are based on the power requirements of the design. Application note SLUU138, UCC38050 100-W Critical Conduction Power Factor Corrected (PFC) Pre-Regulator, explains how to select power semiconductor components for transition-mode PFC pre-regulators. The MOSFET maximum-pulsed drain current (Q1, Q2) is shown in Equation 29: IDM ³ IPEAK = 13 A (29) The MOSFET RMS current calculation (Q1, Q2) is shown in Equation 30: IDS = IPEAK 2 4 Ö2 VIN_MIN 13 A 1 = 6 2 9p ´ VOUT 4 Ö2 ´ 85 V 1 6 9p ´ 390 V » 2.3 A (30) To meet the power requirements of the design, IRFB11N50A 500-V MOSFETs were chosen for Q1 and Q2. The boost diode RMS current (D1, D2) is shown in Equation 31: ID = IPEAK 4 Ö2 VIN_MIN 2 9p ´ VOUT = 13 A 2 4 Ö2 ´ 85 V 9p ´ 390 V » 1.4 A (31) To meet the power requirements of the design, MURS306T3 600-V diodes from On Semiconductor were chosen for the design for D1 and D2. Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 27 UCC28061 SLUS837A – JUNE 2008 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com Brownout Protection Resistor RA and RB are selected to activate brownout protection at 75% of the specified minimum operated input voltage. Resistor RA programs the brownout hysteresis comparator, which was selected to provide 21 V of hysteresis. RA and RB are shown in Equation 32 and Equation 33. In this design example, brownout becomes active when the input drops below 64 VRMS and deactivates when the input reaches 79 VRMS. Hysteresis 21 V RA = = » 3 MW 7 mA 7 mA (32) 1.4 V ´ RA 1.4 V ´ 3 MW RB = = » 47 kW 85 V ´ 0.75 Ö2 - 1.4 V VIN_MIN ´ 0.75 Ö2 - 1.4 V (33) Converter Timing Select the timing resistor, RTSET, for the correct on-time (TON) based on KTL, as shown in Equation 34. To ensure proper operation, the timing must be set based on the highest boost inductance (L1MAX). In this design example, the boost inductor could be as high as 390 µH, based on line and load conditions, as shown in Equation 35. h ´ (VIN_MIN)2 1 fMIN = VIN_MIN ´ Ö2 0.92 ´ (85 V)2 1 - VOUT = POUT ´ L1MAX 133 kW 1 RTSET = 300 W ´ 390 mH VIN_MIN ´ Ö2 VOUT 4.85 V ´ 4 ms ´ fMIN 133 kW 1 = 85 V ´ Ö2 390 V 85 V ´ Ö2 390 V 4.85 V ´ 4 ms ´ 39.2 kHz = 39.2 kHz (34) » 121 kW (35) This result sets the maximum frequency clamp (fMAX), as shown in Equation 36, which improves efficiency at light load. 133 kW 133 kW fMAX = » 550 kHz = 2 ms ´ R T 2 ms ´ 121 kW (36) Programming VOUT Resistor RC is selected to minimize error because of VSENSE input bias current and minimize loading on the power line when the PFC is disabled. Construct resistor RC from two or more resistors in series to meet high-voltage requirements. RC was also selected to be of a similar value of RA and RE to simplify the bill of materials and reduce design costs. Based on the resistor values shown in Equation 37 to Equation 39, the primary output over-voltage protection threshold should be as shown in Equation 40: RC = 3 MW (37) VREF = 6 V RD = (VOUT - VREF) VOVP = 6.45 V 28 (38) VREF ´ RC = RC + RD RD 6 V ´ 3 MW » 47 kW (390 V - 6V) (39) 3 MW + 47 kW = 6.45 V = 418 V 47 kW (40) Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 UCC28061 www.ti.com .............................................................................................................................................................. SLUS837A – JUNE 2008 – REVISED JULY 2009 Loop Compensation Resistor RZ is sized to attenuate low-frequency ripple to less than 2% of the voltage amplifier output range. This value ensures good power factor and low input current harmonic distortion. The transconductance amplifier gain is shown in Equation 41: gm = 96 mS (41) The voltage divider feedback gain is shown in Equation 42 and Equation 43: VREF 6V H= = » 0.015 390 V VOUT (42) 100 mV 100 mV RZ = = = 6.313 kW » 6.34 kW 11 V ´ 0.015 ´ 96 mS VRIPPLE ´ H ´ gm (43) CZ is then set to add 45° of phase margin at 1/5th of the switching frequency, as shown in Equation 44: 1 1 CZ = = = 2.67 mF fLINE 47 Hz 2p ´ ´ 6.34 kW 2p ´ ´ RZ 5 5 (44) CP is sized to attenuate high-frequency noise, as shown in Equation 45: 1 1 CP = = = 1.12 nF fMIN 45 kHz 2p ´ ´ 6.34 kW 2p ´ ´ RZ 2 2 (45) The standard values of Equation 46 and Equation 47 should be chosen for CZ and CP. CZ = 2.2 mF (46) CP = 1 nF (47) ADDITIONAL REFERENCES Related Parts Table 3 lists several TI parts that have characteristics similar to the UCC28061. Table 3. Related Parts DEVICE DESCRIPTION UCC28051 PFC controller for low to medium power applications UCC28019 8-pin continuous conduction mode (CCM) PFC controller UCC28060 Natural Interleaving™ Dual-Phase Transition-Mode PFC Controller References These references, design tools, and links to additional references, including design software, may be found at www.power.ti.com: • Evaluation Module, UCC28060EVM 300W interleaved PFC Pre-regulator, SLUU280 from Texas Instruments • Application Note, UCC38050 100-W Critical Conduction Power Factor Corrected (PFC) Pre-regulator, SLUU138 from Texas Instruments Package Outline and Recommended PCB Footprint The mechanical packages at the end of this data sheet outline the mechanical dimensions of the 16-pin D (SOIC) package and provide recommendations for PCB layout. Submit Documentation Feedback Copyright © 2008–2009, Texas Instruments Incorporated Product Folder Link(s): UCC28061 29 PACKAGE OPTION ADDENDUM www.ti.com 28-Mar-2012 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Qty Eco Plan (2) Lead/ Ball Finish MSL Peak Temp (3) Samples (Requires Login) UCC28061D ACTIVE SOIC D 16 40 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM Add to cart UCC28061DG4 ACTIVE SOIC D 16 40 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM Add to cart UCC28061DR ACTIVE SOIC D 16 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM Add to cart UCC28061DRG4 ACTIVE SOIC D 16 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM Add to cart (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. 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OTHER QUALIFIED VERSIONS OF UCC28061 : Addendum-Page 1 PACKAGE OPTION ADDENDUM www.ti.com 28-Mar-2012 • Automotive: UCC28061-Q1 NOTE: Qualified Version Definitions: • Automotive - Q100 devices qualified for high-reliability automotive applications targeting zero defects Addendum-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 29-Apr-2009 TAPE AND REEL INFORMATION *All dimensions are nominal Device UCC28061DR Package Package Pins Type Drawing SOIC D 16 SPQ Reel Reel Diameter Width (mm) W1 (mm) 2500 330.0 16.4 Pack Materials-Page 1 A0 (mm) B0 (mm) K0 (mm) P1 (mm) 6.5 10.3 2.1 8.0 W Pin1 (mm) Quadrant 16.0 Q1 PACKAGE MATERIALS INFORMATION www.ti.com 29-Apr-2009 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) UCC28061DR SOIC D 16 2500 333.2 345.9 28.6 Pack Materials-Page 2 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. 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