TPS40322 SLUSAF8 – JUNE 2011 www.ti.com Dual Output or Two-Phase Synchronous Buck Controller FEATURES DESCRIPTION • The TPS40322 is a dual-output, synchronous buck controller. It can also be configured as a single-output, two-phase controller. The 180° out-of-phase operation reduces the input current ripple and extends the input capacitor lifetime. Bi-directional master/slave synchronization function provides evenly distributed phase shift for a four-output system that reduces input ripple further and attenuates the system noise. 1 • • • • • • • • • • • • • • • • • • Dual- or Multi-phase Synchronous Buck Controller 180° Out-of-Phase Reduces Input Ripple Input Voltage Range from 3 V to 20 V Output Voltage Range: 0.6 V to 5.6 V Adjustable Frequency 100 kHz to 1 MHz Bidirectional SYNC with 0°/180° or 90°/270° Phase Shift Voltage Mode Control With Input Feed-forward Accurate Current Sharing for Multi-phase Operation Individual PowerGood Outputs Individual Enable and Programmable Soft Start, With Pre-bias Start-up ±0.5%, 600-mV Reference Output UV/OV Protection and Input Undervoltage Lockout Individual Overcurrent Limit Setting Hiccup Overcurrent Protection Accurate Inductor DCR or Resistive Current Sensing Remote Sense for Multi-phase Applications Internal N-Channel FET Drivers Integrated Bootstrap Switches Available in 5 mm × 5 mm 32-Pin QFN Package The wide input range can support 3.3-V, 5-V, and 12-V buses. The accurate reference voltage satisfies the precision voltage need of the modern ASICs and potentially reduces the output capacitance requirement. Separate PGOOD signals provide flexibility for system monitoring and sequencing. The two channels are independently controlled and each soft-start time is programmable. Voltage mode control is implemented to reduce noise sensitivity and also ensures low duty ratio conversion. . SIMPLIFIED APPLICATION CIRCUIT 26 VIN 3V to 20 V 20 31 UVLO APPLICATIONS • • • • • BP6 VDD 24 HDRV1 HDRV2 16 25 BOOT1 BOOT2 15 23 SW1 Multiple Rail Systems Telecom Base Station Switcher/Router Networking xDSL Broadband Access Server and Storage System SW2 17 22 LDRV1 LDRV2 18 21 PGND1 PGND2 19 30 ILIM1 ILIM2 11 28 CS1+ CS2+ 13 VOUT2 TPS40322 VOUT1 29 CS1– CS2– 12 27 PG1 PG2 14 4 FB1 9 DIFFO 5 COMP1 2 RT FB2 8 COMP2 7 SYNC 1 PHSET 32 EN/SS1 AGND EN/SS2 3 6 10 UDG-10215 1 Please be aware that an important notice concerning availability, standard warranty, and use in critical applications of Texas Instruments semiconductor products and disclaimers thereto appears at the end of this data sheet. PRODUCTION DATA information is current as of publication date. Products conform to specifications per the terms of the Texas Instruments standard warranty. Production processing does not necessarily include testing of all parameters. Copyright © 2011, Texas Instruments Incorporated TPS40322 SLUSAF8 – JUNE 2011 www.ti.com 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. ORDERING INFORMATION (1) (1) TEMPERATURE RANGE PINS PACKAGE ORDERING NUMBER –40°C to 125°C 32 QFN TPS40322RHB For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI website at www.ti.com. ABSOLUTE MAXIMUM RATINGS (1) Over operating free-air temperature range, all voltages are with respect to GND (unless otherwise noted) VALUE VDD SW1, SW2 (2) UNIT MIN MAX –0.3 22 V –3 27 V –5 V 30 V SW1, SW2 (<100 ns pulse width) (2) Voltage Range BOOT1, BOOT2 (2) –0.3 BP6 –0.3 7 V –2 30 V All other pins –0.3 7 V TJ Operating temperature –40 145 °C Tstg Storage temperature –55 150 °C HDRV1, HDRV2 (2) Temperature Electrostatic disharge Human Body Model (HBM) 2000 V Charged Device Model (CDM) 1500 V Soldering (1) (2) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, and functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions is not implied. Exposure to absolute maximum rated conditions for extended periods may affect device reliability. BOOT to SW and HDRV to SW are relative measurements. RECOMMENDED OPERATING CONDITIONS VVDD Input operating voltage TJ Operating junction temperature 2 MIN MAX 3 20 UNIT V –40 125 °C Copyright © 2011, Texas Instruments Incorporated TPS40322 SLUSAF8 – JUNE 2011 www.ti.com THERMAL INFORMATION TPS40322 THERMAL METRIC (1) QFN UNITS 32 PINS Junction-to-ambient thermal resistance (2) θJA (3) 37.3 θJCtop Junction-to-case (top) thermal resistance θJB Junction-to-board thermal resistance (4) 10.0 ψJT Junction-to-top characterization parameter (5) 0.4 ψJB Junction-to-board characterization parameter (6) 9.9 θJCbot Junction-to-case (bottom) thermal resistance (7) 2.7 (1) (2) (3) (4) (5) (6) (7) 28.6 °C/W For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953. The junction-to-ambient thermal resistance under natural convection is obtained in a simulation on a JEDEC-standard, high-K board, as specified in JESD51-7, in an environment described in JESD51-2a. The junction-to-case (top) thermal resistance is obtained by simulating a cold plate test on the package top. No specific JEDEC-standard test exists, but a close description can be found in the ANSI SEMI standard G30-88. The junction-to-board thermal resistance is obtained by simulating in an environment with a ring cold plate fixture to control the PCB temperature, as described in JESD51-8. The junction-to-top characterization parameter, ψJT, estimates the junction temperature of a device in a real system and is extracted from the simulation data for obtaining θJA, using a procedure described in JESD51-2a (sections 6 and 7). The junction-to-board characterization parameter, ψJB, estimates the junction temperature of a device in a real system and is extracted from the simulation data for obtaining θJA , using a procedure described in JESD51-2a (sections 6 and 7). The junction-to-case (bottom) thermal resistance is obtained by simulating a cold plate test on the exposed (power) pad. No specific JEDEC standard test exists, but a close description can be found in the ANSI SEMI standard G30-88. Copyright © 2011, Texas Instruments Incorporated 3 TPS40322 SLUSAF8 – JUNE 2011 www.ti.com ELECTRICAL CHARACTERISTICS TJ = –40°C to 125°C, VVDD = 12 V, RRT = 40 kΩ, fSW = 500 kHz (unless otherwise noted), PARAMETER TEST CONDITIONS MIN TYP MAX UNITS 20 V 200 250 µA 6 8 mA 1.21 1.24 1.27 V 13 15 17 μA 6.2 6.5 6.8 V 50 100 mV INPUT SUPPLY VDD Input voltage range IDDSDN Shutdown VENx/SSx = 0 V 3 IDDQ Quiescent, non-switching VFB = 0.65 V, ENx/SSx float UVLO UVLO Minimum turn-on voltage UVLOHYS Hysteresis current BP REGULATOR BP Regulator voltage 7 ≤ VVDD ≤ 20 V VDO Regulator dropout voltage IBP = 25 mA, VVDD = 3 V IBP Regulator continuous current limit (1) 100 VBPUVLO Regulator output UVLO 2.40 2.70 2.95 V VBPUVLO-HYS Regulator output UVLO hysteresis 180 210 250 mV 1000 kHz 550 kHz mA OSCILLATOR/ RAMP GENERATOR 100 fSW Oscillator frequency VRAMP Ramp amplitude (preak-to-peak) VVAL Valley voltage fSYNC SYNC frequency range 200 tPW(sync) SYNC input minimum pulse width 100 VH(sync) Rising edge threshold to set sync pulse VL(sync) Falling edge threshold to reset sync pulse fMASTER Master clock frequency ΔfSYNC Percent of master frequency for synchronization VPHSET RRT = 40 kΩ 450 3 V < VVDD < 20 V 500 VDD/8.5 V 0.85 V 2000 ns 2 V 0.8 200 2000 –20% 20% Master 0°/180° phase shift Slave 0°/180° phase shift 0.6 Slave 90°/270° phase shift 2.1 kHz V kHz 0.5 V 2.0 V V PWM PWM(off) Minimum PWM off-time tON(min) Minimum controllable pulse width See 90 tDEAD Output driver dead time HDRV off to LDRV on 20 35 40 ns tDEAD Output driver dead time LDRV off to HDRV on 20 35 40 ns 0°C < TJ < 70°C 597 600 603 mV –40°C < TJ < 125°C 594 600 606 20 75 (1) 130 90 ns ns ERROR AMPLIFIER AND VOLTAGE REFERENCE VFB FB input voltage IFB FB input bias current GBWP Unity gain bandwidth See (1) AVOL Open loop gain See (1) IOH IOL (1) 4 nA 24 MHz High-level output current 3 mA Low-level output current 9 mA 80 dB Specified by design. Not production tested. Copyright © 2011, Texas Instruments Incorporated TPS40322 SLUSAF8 – JUNE 2011 www.ti.com ELECTRICAL CHARACTERISTICS (continued) TJ = –40°C to 125°C, VVDD = 12 V, RRT = 40 kΩ, fSW = 500 kHz (unless otherwise noted), PARAMETER TEST CONDITIONS MIN TYP MAX UNITS V ENABLE/SOFT START VIH High-level input voltage 0.55 0.70 1.00 VIL Low-level input voltage 0.23 0.26 0.30 V ISS Soft-start source current 8 10 12 μA VSS Soft-start voltage level 0.8 V IDISCHG Soft-start discharge current 130 μA OVERCURRENT PROTECTION IILIM ILIM program current tHICCUP Hiccup cycles to recover TJ = 25°C 9.5 10.0 10.5 6 μA Cycles CURRENT SENSE AMPLIFIER VDIFF Differential input voltage range VCM Input common mode range ACS Current sensing gain VCSOUT Current sense amplifier output fC0 Closed loop bandwidth (2) Current sense amplifier output difference between CH1 and CH2 –60 60 0 5.6 15 VCSIN = 20 mV, TJ = 25°C 270 300 V V/V 330 3 VCSIN = 20 mV to both CS1 and CS2 mV mV MHz –15 15 mV OVERVOLTAGE/UNDERVOLTAGE PROTECTION VOVP Feedback voltage limit for OVP 679 700 735 mV VUVP Feedback voltage limit for UVP 475 500 525 mV GATE DRIVERS RHDHI High-side driver pull-up resistance VBOOT – VSW = 6.5 V, IHDRV = –40 mA 0.8 1.5 2.5 Ω RHDLO High-side driver pull-down resistance VBOOT – VSW = 6.5 V, IHDRV = 40 mA 0.5 1.0 1.6 Ω RLDHI Low-side driver pull-up resistance ILDRV = –40 mA 0.8 1.5 2.5 Ω RLDLO Low-side driver pull-down resistance ILDRV = 40 mA 0.35 0.60 1.30 tHRISE High-side driver rise time CLOAD = 5 nF, See (2) 15 ns tHFALL High-side driver fall time CLOAD = 5 nF, See (2) 12 ns tLRISE Low-side driver rise time CLOAD = 5 nF, See (2) 15 ns tLFALL Low-side driver fall time CLOAD = 5 nF, See (2) 10 ns Bootstrap switch voltage drop IBOOT = 5 mA 0.1 V VIOFSET Input offset voltage VDIFFO = 0.9 V Gain Differential gain BW Close loop bandwidth (2) VDIFFO Output voltage at DIFFO pin ISRC Output source current 1 mA ISNK Output sink current 1 mA Ω BOOT SWITCH VDFWD REMOTE SENSE –2 2 mV 0.995 1.005 V/V 2.00 MHz VBP6-0.2 V POWERGOOD VOV Feedback voltage limit for PGOOD 650 675 697 mV VUV Feedback voltage limit for PGOOD 510 525 545 mV VPGD(hyst) PGOOD hysteresis voltage at FB 25 40 mV RRGD PGOOD pull down resistance 50 70 Ω IPGD(leak) PGOOD leakage current 20 µA THERMAL SHUTDOWN TSD Junction shutdown temperature See (2) 150 °C TSD(hyst) Hysteresis See (2) 20 °C (2) Specified by design. Not production tested. Copyright © 2011, Texas Instruments Incorporated 5 TPS40322 SLUSAF8 – JUNE 2011 www.ti.com TYPICAL CHARACTERISTICS 1.2355 UVLO Hysteresis Current (µA) 15.8 UVLO Turn−On Voltage (V) 1.2350 1.2345 1.2340 1.2335 1.2330 −40 −25 −10 5 20 35 50 65 80 Junction Temperature (°C) 95 15.6 15.4 15.2 15.0 14.8 14.6 14.4 −40 −25 −10 110 125 Figure 1. UVLO Turn-On Voltage vs. Junction Temperature 10.9 10.8 10.7 10.6 10.5 5 20 35 50 65 80 Junction Temperature (°C) 95 110 125 Non−Switching Quiescent Current (mA) Soft−Start Current (µA) 11.0 10.4 6.35 6.30 6.25 6.20 6.15 6.10 6.05 6.00 5 20 35 50 65 80 Junction Temperature (°C) 95 110 125 Figure 4. Non-Switching Quiescent Current vs. Junction Temperature 2.80 BP UVLO Threshold Voltage (V) 601.5 Error Amplifier Feedback Voltage (V) 6.40 5.95 −40 −25 −10 G001 Figure 3. Soft-Start Current vs. Junction Temperature 601.0 600.5 600.0 599.5 599.0 598.5 5 20 35 50 65 80 Junction Temperature (°C) 95 110 125 G001 Figure 5. Error Amplifier Feedback Voltage vs. Junction Temperature 6 110 125 6.45 11.1 598.0 −40 −25 −10 95 Figure 2. UVLO Hysteresis Current vs. Junction Temperature 11.2 10.3 −40 −25 −10 5 20 35 50 65 80 Junction Temperature (°C) Falling Rising 2.75 2.70 2.65 2.60 2.55 2.50 2.45 2.40 −40 −25 −10 5 20 35 50 65 80 Junction Temperature (°C) 95 110 125 G001 Figure 6. BP UVLO Threshold vs. Junction Temperature Copyright © 2011, Texas Instruments Incorporated TPS40322 SLUSAF8 – JUNE 2011 www.ti.com 780 290 760 High Level Input Voltage (mV) Low Level Input Voltage (mV) TYPICAL CHARACTERISTICS (continued) 300 280 270 260 250 240 230 −40 −25 −10 5 20 35 50 65 80 Junction Temperature (°C) 95 680 660 640 10.3 10.2 10.1 10.0 9.9 95 110 125 0.8 0.6 0.4 0.2 0.0 −0.2 −0.4 −40 −25 −10 Switching Frequency (kHz) 105.8 1.0000 0.9999 0.9998 0.9997 0.9996 0.9995 95 110 125 G001 105.6 105.4 105.2 105.0 104.8 104.6 104.4 104.2 110 125 G001 Figure 11. Remote Sense Gain vs. Junction Temperature Copyright © 2011, Texas Instruments Incorporated 5 20 35 50 65 80 Junction Temperature (°C) Figure 10. Remote Sense Input Offset Voltage vs. Junction Temperature 1.0001 95 G001 1.0 106.0 5 20 35 50 65 80 Junction Temperature (°C) 110 125 1.2 1.0002 0.9994 −40 −25 −10 95 1.4 G001 Figure 9. Current Limit vs. Junction Temperature 5 20 35 50 65 80 Junction Temperature (°C) Figure 8. ENx High-Level Inout Voltage vs. Junction Temperature Remote Sense Input Offset Voltage (V) ILIM1 Program Current (µA) 10.4 9.8 Remote Sense Gain 700 G001 10.5 5 20 35 50 65 80 Junction Temperature (°C) 720 620 −40 −25 −10 110 125 Figure 7. ENx Low-Level Inout Voltage vs. Junction Temperature 9.7 −40 −25 −10 740 RRT = 200 kΩ VVDD = 12 V 104.0 −40 −25 −10 5 20 35 50 65 80 Junction Temperature (°C) 95 110 125 G001 Figure 12. Frequency vs. Junction Temperature 7 TPS40322 SLUSAF8 – JUNE 2011 www.ti.com TYPICAL CHARACTERISTICS (continued) 520 Switching Frequency (kHz) Switching Frequency (kHz) 1040 1035 1030 1025 1020 5 20 35 50 65 80 Junction Temperature (°C) 95 110 125 Figure 13. Frequency vs. Junction Temperature 8 500 490 480 470 460 RRT = 20 kΩ VVDD = 12 V 1015 −40 −25 −10 510 G001 VVDD = 7 V VVDD = 12 V VVDD = 14 V VVDD = 20 V 450 −40 −25 −10 5 20 35 50 65 80 Junction Temperature (°C) RRT = 40 kΩ 95 110 125 G001 Figure 14. Frequency vs. Junction Temperature Copyright © 2011, Texas Instruments Incorporated TPS40322 SLUSAF8 – JUNE 2011 www.ti.com DEVICE INFORMATION FUNCTIONAL BLOCK DIAGRAM BP6 Linear Regulator VDD 26 AGND BG 6 BP6 VREF PWM Logic CS1+ 28 25 BOOT1 + 24 HDRV1 VREF FB1 4 EN1/SS1 3 + + – – – 23 SW1 20 BP6 22 LDRV1 10 ?A COMP1 Σ PWM1 Anti-Cross Conduction Ramp1 CS1- 29 21 PGND1 ISHARE 5 BP6 VREF FB2 8 EN2/SS2/GSNS 10 + – – – Σ + 15 BOOT2 PWM2 Ramp2 16 HDRV2 COMP2 Anti-Cross Conduction 10 ?A 7 CS2+ 13 + OC FB1 CS2- 12 FB2 ILIM1 30 OC UV OV Detect 17 SW2 BP6 18 LDRV2 UV 19 PGND2 OV ILIM2/VSNS 11 27 PG1 UVLO 31 14 PG2 DIFFO 9 SYNC 1 RT 2 R RAMP1 Ramp Generator PHSET 32 R VSNS + RAMP2 R GSNS R UDG-10216 NOTE • • • In multi-phase mode, the EN2/SS2/GSNS pin becomes the GSNS pin and the ILIM2/VSNS pin becomes the VSNS pin. The two channels are identical unless specified. The following naming conventions are used to better describe the functions. For example, COMPx refers to COMP1 and COMP2, FBx refers to FB1 and FB2. Copyright © 2011, Texas Instruments Incorporated 9 TPS40322 SLUSAF8 – JUNE 2011 UVLO ILIM1 CS1– CS1+ PG1 VDD 32 31 30 29 28 27 26 BOOT1 PHSET www.ti.com SYNC 1 25 24 RT 2 23 SW1 EN1/SS1 3 22 LDRV1 FB1 4 21 PGND1 COMP1 5 20 BP6 AGND 6 19 PGND2 7 18 LDRV2 8 17 SW2 10 11 12 13 14 15 16 CS2– CS2+ PG2 BOOT2 HDRV2 DIFFO 9 ILIM2/VSNS FB2 EN2/SS2/GSNS COMP2 TPS40322RHB HDRV1 PIN FUNCTIONS NAME PIN I/O AGND 6 – Low noise ground connection to the controller. BOOT1 25 I BOOT1 provides a bootstrapped supply for the high-side FET driver for channel 1 (CH1). Connect a capacitor (0.1 μF typical) from BOOT1 to SW1 pin. BOOT2 15 I BOOT2 provides a bootstrapped supply for the high-side FET driver for channel 2 (CH2). Connect a capacitor (0.1 μF typical) from BOOT2 to SW2 pin. BP6 20 O Output bypass for the internal regulator. Connect a low ESR bypass ceramic capacitor with a value of 3.3 μF or greater from this pin to the power ground plane. COMP1 5 O Output of the error amplifier 1 and connection node for loop feedback components. COMP2 7 O Output of the error amplifier 2 and connection node for loop feedback components. CS1– 29 I Negative terminal of current sense amplifier for CH1 CS1+ 28 I Positive terminal of current sense amplifier for CH1 CS2– 12 I Negative terminal of current sense amplifier for CH2 CS2+ 13 I Positive terminal of current sense amplifier for CH2 DIFFO 9 O Output of the differential amplifier. When the device is configured for dual channel mode, the DIFFO pin must be either floating or tied to BP6 I Logic level input which starts or stops CH1. Letting this pin float turns CH1 on. Pulling this pin low disables CH1. This is also the soft-start programming pin. A capacitor connected from this pin to AGND programs the soft-start time. The capacitor is charged with an internal current source of 10 μA. The resulting voltage ramp of this pin is also used as a second non-inverting input to the error amplifier 1 after a 0.8 V (typical) level shift downwards. EN1/SS1 3 DESCRIPTION EN2/SS2/GSNS 10 I Logic level input which starts or stops CH2. Letting this pin float turns CH2 on. Pulling this pin low disables CH2. This is also the soft-start programming pin. A capacitor connected from this pin to AGND programs the soft-start time. The capacitor is charged with an internal current source of 10 μA. The resulting voltage ramp of this pin is also used as a second non-inverting input to the error amplifier 2 after a 0.8 V (typical) level shift downwards.In multi-phase mode, this pin becomes GSNS as the negative terminal of a remote sense amplifier. FB1 4 I Inverting input to the error amplifier. During normal operation, the voltage on this pin is equal to the internal reference voltage. FB2 8 I Inverting input to the error amplifier. During normal operation, the voltage on this pin is equal to the internal reference voltage. Connecting the FB2 pin to the BP6 pin enables multi-phase mode and disables the error amplifier 2. HDRV1 24 O Bootstrapped gate drive output for the high-side N-channel MOSFET for CH1. A 2-Ω resistor is recommended for a noisy environment. 10 Copyright © 2011, Texas Instruments Incorporated TPS40322 SLUSAF8 – JUNE 2011 www.ti.com PIN FUNCTIONS (continued) NAME PIN I/O DESCRIPTION HDRV2 16 O Bootstrapped gate drive output for the high-side N-channel MOSFET for CH2. A 2-Ω resistor is recommended for a noisy environment. ILIM1 30 I Used to set the overcurrent limit for CH1 with 10 μA of current flowing through a resistor from this pin to AGND. ILIM2/VSNS 11 I Used to set the overcurrent limit for CH2 with 10 μA of current flowing through a resistor from this pin to AGND. In multi-phase mode, this pin becomes VSNS as the positive terminal of a remote sense amplifier. LDRV1 22 O Gate drive output for the low-side synchronous rectifier (SR) N-channel MOSFET for CH1. LDRV2 18 O Gate drive output for the low-side synchronous rectifier (SR) N-channel MOSFET for CH2. PG1 27 O Open drain power good indicator for CH1 output voltage. PG2 14 O Open drain power good indicator for CH2 output voltage. PGND1 21 - Power ground 1. Separate power ground for CH1 and CH2 in the PCB layout could potentially reduce channel to channel interference. PGND2 19 - Power ground 2. Separate power ground for CH1 and CH2 in the PCB layout could potentially reduce channel to channel interference. PHSET 32 I Used to set master or slave mode and phase angles. The master emits a 50% duty clock to the slave. The slave synchronizes to the external clock and select the phase shift angle. RT 2 I Connect a resistor from this pin to AGND to set the oscillator frequency. SW1 23 I Connect to the switched node on converter CH1. It is the return for the CH 1 high-side gate driver. SW2 17 I Connect to the switched node on converter CH2. It is the return for the CH 2 high-side gate driver. SYNC 1 I/O UVLO 31 I A resistor divider from VIN determines the input voltage that the controller starts. VDD 26 I Power input to the controller. A low ESR bypass ceramic capacitor of 0.1 μF or greater should be connected closely from this pin to AGND. In master mode, a 2x free running frequency clock is sent out on SYNC pin. In slave mode, sync to an external clock which is ±20% of the free running MASTER_CLOCK frequency. The MASTER_CLOCK frequency is 2x of the free running frequency (set by RT) and operates at 50% duty cycle. Copyright © 2011, Texas Instruments Incorporated 11 TPS40322 SLUSAF8 – JUNE 2011 www.ti.com FUNCTIONAL DESCRIPTION General Description/Control Architecture The TPS40322 is a flexible synchronous buck controller. It can be used as a dual-output controller, or as a multi-phase single-output controller. It operates with a wide input range from 3 V to 20 V and generates accurate regulated output as low as 600 mV. In dual output mode, voltage mode control with input feed-forward architecture is implemented. With this architecture, the benefits are less noise sensitivity, no control instability issues for small DCR applications, and a smaller minimum controllable on-time, often desired for high conversion ratio applications. In two-phase single-output mode, a current-sharing loop is implemented to ensure a balance of current between phases. Because the induced error current signal to the loop is much smaller when compared to the PWM ramp amplitude, the control loop is modeled as voltage mode with input feed-forward. DESIGN NOTE • When the device is operating in dual output mode, DIFFO must be floating or tied to BP6. Voltage Reference The 600-mV bandgap cell is internally connected to the non-inverting input of the error amplifier. The reference voltage is trimmed with the error amplifier in a unity gain configuration to remove amplifier offset from the final regulation voltage. The 0.5-% tolerance on the reference voltage allows the user to design a very accurate power supply. Output Voltage Setting The output voltages of the TPS40322 are set by using external feedback resistor dividers as shown in Figure 15. The regulated output voltage (VOUT) is determined by Equation 1. RA VOUTx COMPx + RBIAS VREF UDG-11111 Figure 15. Setting the Output Voltage æ RA ö VOUT = 0.6 V ´ ç 1 + ÷ è RBIAS ø 12 (1) Copyright © 2011, Texas Instruments Incorporated TPS40322 SLUSAF8 – JUNE 2011 www.ti.com Input Voltage Feed-Forward The TPS40322 uses input voltage feed-forward to maintain a constant power stage gain as the input voltage varies and provides very good response to input voltage transient disturbances. The simple constant power stage gain of the controller greatly simplifies feedback loop design because the loop characteristics remain constant as the input voltage changes, unlike a typical buck converter without voltage feed-forward. For modeling purposes, the gain from the COMP pin to the average voltage at the input of the L-C filter is typically 8.5 V/V. Current Sensing The TPS40322 uses a differential current sense design to sense the output current. The sense element can be either the series resistance of the power stage filter inductor or a separate current sense resistor. When using the inductor series resistance as shown in Figure 16, an R-C filter must be used to remove the large AC component voltage across the inductor so that only the component of the voltage that remains is across the resistance of the inductor. (See Figure 16) The values of R1 and C1 for an ideal design can be calculated using Equation 2. The time constant of the R-C filter should equal the time constant of the inductor itself. If the time constants are equal, the voltage across C1 equals the current in the inductor multiplied by the inductor resistance. The inductor ripple current is reflected in the voltage across C1. Typically a capacitor with a value of 0.1-µF is recommended for C1. Please refer to the LAYOUT CONSIDERATIONS section for proper placement of the sensing elements. VIN L1 L DCR R1 VOUT1 C1 + VC R1´ C1 = L1 DCR (2) – CS1– CS1+ UDG-11112 Figure 16. Inductor DCR Current Sensing Copyright © 2011, Texas Instruments Incorporated 13 TPS40322 SLUSAF8 – JUNE 2011 www.ti.com Overcurrent Protection The TPS40322 has dedicated ILIM pins for each channel for use when operating in dual-output mode. When operating in multi-phase mode, both channels share the same overcurrent level set by ILIM1. The overcurrent level is set with a resistor connected from the ILIMx pin to analog ground. The sensed current signal is amplified by the CS amplifier with a gain of 15, and then compared with the established overcurrent level to determine if there is an OC fault. This design is shown in Figure 17. IOUT L1 L DCR VOUT1 SW1 R1 C1 CS1+ CS1– ACS=15 + ILIM1 10 A + OC RILIM UDG-11114 Figure 17. Overcurrent Protection Equation 3 shows the current limit resistance (RLIM) calculation for desired overcurrent limit. æ æ IRIPPLE ö ö ç IOC + ç ÷ ´ DCR ´ A CS 2 ÷ø ø è è RLIM = IILIM where • • • • • IOC is the desired DC over current limit level IRIPPLE is the inductor peak-peak ripple current DCR is the inductor DC resistance ACS is the current sensing amplifier gain (typically 15) IILIM is the internal source current out of ILIMx pin (typically 10 µA) (3) The TPS40322 implements cycle-by-cycle current limit when the inductor peak current has exceeded the set limit. When the controller counts three consecutive clock cycles of an overcurrent condition, the high-side and low-side MOSFETs are turned off and the controller enters a hiccup mode. After six soft-start cycles, normal switching is attempted. If the overcurrent has cleared, normal operation resumes, otherwise the sequence repeats. 14 Copyright © 2011, Texas Instruments Incorporated TPS40322 SLUSAF8 – JUNE 2011 www.ti.com Multi-Phase Mode and Current Sharing Loop The TPS40322 can be configured to operate in single-output multi-phase mode for high-current applications. With proper selection of the external MOSFETs, this device can support up to 50-A of load current in a multi-phase configuration. As shown in Figure 18, to configure TPS40322 as multi-phase mode, FB2 is tied to BP6. In this mode, COMP1 must be connected to COMP2 to ensure current sharing between the two phases. For high-current applications, the remote sense amplifier is used to compensate for the parasitic offset to provide an accurate output voltage. The EN2/SS2 and ILIM2 pins are designed for multiple functions. They are used as VSNS and GSNS for remote sensing in a multi-phase mode. DIFFO, which is the output of the remote sensing amplifier, is connected to the resistor divider of the feedback network. Power Stage RPARASITIC L O A D COMP2 COMP1 FB2 RPARASITIC BP6 R GSNS ILIM2/VSNS R + VSNS EN2/SS2/GSNS R R DIFFO + VREF FB1 COMP1 UDG-11113 Figure 18. Multi-phase Mode Configuration When the device operates in multi-phase mode, a current sharing loop as shown in Figure 19 is designed to maintain the current balance between phases. Both phases share the same comparator voltage (COMP1). The sensed current in each phase is compared first in a current share block, then an error current and fed into COMP. The resulted error voltage is compared with the voltage ramp to generate the PWM pulse. Copyright © 2011, Texas Instruments Incorporated 15 TPS40322 SLUSAF8 – JUNE 2011 www.ti.com IO1 L1 DCR L SW1 VOUT R1 C1 CS1+ CS1– ISNS2 ISNS1 ISHARE Block + FB1 + VREF – + PWM1 COMP1 PWM2 + – + ISNS2 ISHARE Block ISNS1 CS2+ CS2– C2 R2 IO2 L DCR SW2 L2 VOUT UDG-11115 Figure 19. Multi-phase Mode Current Share Loop 16 Copyright © 2011, Texas Instruments Incorporated TPS40322 SLUSAF8 – JUNE 2011 www.ti.com Startup and Shutdown Startup Sequence When the ENx/SSx pin is pulled below 0.3 V, the respective channel is disabled. When ENx/SSx is released, the controller starts automatically and an internal 40-µA current source begins to charge the external soft-start capacitor. When the voltage across the soft-start capacitor is over 0.7 V, the internal BP regulator is enabled. The ENx/SSx voltage is clamped to 1.3 V while waiting for signals indicating that BP6, VDD, and the oscillator clock are good. After all the signals are confirmed, ENx/SSx is discharged to 0.4 V with a 140-µA current source, and then charged again with the internal 10-µA current source. The operation is described by the waveform shown in Figure 20. VSS_INT is an internal signal level shifted from ENx/SSx and then connected to the non-inverting terminal of the error amplifier. The soft-start time is determined by the internal charge current and the external capacitance. The actual output ramp-up time is the time for the internal current source to charge the capacitor through a 600 mV range. There is some initial lag time due to the offset (800 mV typical) from the actual ENx/SSx pin voltage to VSS_INT. The soft-start sequence takes place in a closed loop fashion, meaning that the error amplifier controls the output voltage constantly during the soft-start period and the feedback loop is never open (as occurs in duty cycle limit soft-start designs). The error amplifier has two non-inverting inputs, one connected to the 600-mV reference voltage, and the other connected to the offset VSS_INT. The error amplifier controls the FB pin to the lower of these two voltages. As the voltage on the ENx/SSx pin ramps up past approximately 1.4 V (800 mV offset voltage plus the 600 mV reference voltage), the 600 mV reference voltage becomes the dominant input and the converter has reached its final regulation voltage. Equation 4 shows how to calculate the soft start capacitance. Voltage (V) VEN1/SS1 t ´I CSS = SS SS 600mV where 1.3 • 0.8 VSS_INT 0.4 • • CSS is the soft start capacitance connected to ENx/SSx pin tSS is the desired soft-start time ISS is the internal soft-start current (typically 10 µA) (4) Time Figure 20. EN/SS Start-Up Waveform Pre-Biased Output Start-Up The TPS40322 contains a circuit that prevents current from being pulled from the output during the start-up sequence in a pre-biased output condition. There are no PWM pulses until the internal soft-start voltage rises above the error amplifier input (FBx pin), if the output is pre-biased. Once the soft-start voltage exceeds the error amplifier input, the device slowly initiates synchronous rectification by starting the synchronous rectifier with a narrow on-time. It then increments that on-time on a cycle-by-cycle basis until it coincides with the time dictated by (1-D), where D is the duty cycle of the converter. This approach prevents the sinking of current from a pre-biased output, and ensures the output voltage start-up and ramp-to-regulation sequences are smooth and controlled. DESIGN NOTE During the soft-start sequence, when the PWM pulse width is shorter than the minimum controllable on-time, which is generally caused by the PWM comparator and gate driver delays, pulse skipping may occur and the output might show larger ripple voltage. Copyright © 2011, Texas Instruments Incorporated 17 TPS40322 SLUSAF8 – JUNE 2011 www.ti.com Shutdown During the shutdown sequence, BP6 is controlled by ENx/SSx. If both of ENx/SSx pins are pulled low, BP6 is turned off regardless of the input voltage remaining higher than programmed UVLO threshold. Switching Frequency and Master/Slave Synchronization The switching frequency is set by the value of the resistor connected from the RT pin to AGND. The RT resistor value is calculated in Equation 5. RRT = 20 ´ 109 fSW where • • RRT is the the resistor from RT pin to AGND, in Ω fSW is the desired switching frequency, in Hz (5) The TPS40322 device can also synchronize to an external clock that is ±20% of the master clock frequency which is two times the free running frequency. Each TPS40322 can be set by the PHSET pin as either master or slave. The master produces a 50% duty cycle clock to the slave. The slave synchronizes to the external clock with 50% duty cycle and selects the phase shift angle as shown in Table 1. Figure 21 shows an example on synchronizing two TPS40322 devices to generate an evenly distributed shift to reduce input ripple. Table 1. Phase Shift Angle Selection PHSET CONNECTION MODE RANGE (V) PHASE ANGLE (°) CH1 CH2 AGND < 0.5 Master 0 180 Floating 0.6 to 2 Slave 0 180 High > 2.1 Slave 90 270 XXXX XXXX TPS40322 Master PHSET PWM1 PWM1 0° PWM2 PWM2 180° PWM1 PWM1 90° PWM2 PWM2 270° SYNC TPS40322 Slave SYNC BP6 PHSET UDG-11117 Figure 21. Synchronizing Two TPS40322 Devices 18 Copyright © 2011, Texas Instruments Incorporated TPS40322 SLUSAF8 – JUNE 2011 www.ti.com Overvoltage and Undervoltage Fault Protection The TPS40322 has output overvoltage protection and undervoltage protection capability. The comparators that regulate the overvoltage and undervoltage conditions use the FBx pin as the output sensing point so the filtering effect of the compensation network connected from COMPx to FBx has an effect on the speed of detection. As the output voltage rises or falls below the nominal value, the error amplifier attempts to force FBx to match its reference voltage. When the error amplifier is no longer able to do this, the FB pin begins to drift and trip the overvoltage threshold (VOVP) or the undervoltage threshold (VUVP) as described in the ELECTRICAL CHARACTERISTICS table. When an undervoltage fault is detected, the TPS40322 enters hiccup mode and resumes normal operation when the fault is cleared. When an overvoltage fault is detected, the TPS40322 turns off the high-side MOSFET and latches on the low-side MOSFET to discharge the output current to the regulation level (within the power good window) When operating in dual-channel mode, both channels have identical but independent protection schemes which means one channel would not be affected when the other channel is in fault mode. When operating in multi-phase mode, only the FB1 pin is detected for overvoltage and undervoltage fault. Therefore both channels take action together during a fault. Input Undervoltage Lockout (UVLO) A dedicated UVLO pin allows the user to program the desired input turn-on threshold voltage. The diagram is shown in Figure 22. The desired input turn-on threshold can be calculated using Equation 6. The input turn off hysteresis can be calculated using Equation 7. 15 mA VIN æ (RON1 + RON2 ) ö VIN _ UVLO = 1.24 V ´ ç ÷ ç ÷ RON2 è ø (6) VIN _ HYS = 15 mA ´ RON1 (7) RON 1 UVLO + VIN_OK RON 2 TPS40322 UDG-11118 Figure 22. Input UVLO Diagram Power Good The TPS40322 provides an indication that output is good for each channel. This is an open-drain signal and pulls low when any condition exists that would indicate that the output of the supply might be out of regulation. These conditions include: • Feedback voltage (VFB) is more than ±12.5% from nominal • Soft-start is active Thermal Shutdown If the junction temperature of the device reaches the thermal shutdown limit of 150°C, the PWMs and the oscillators are turned off and HDRVs and LDRVs are driven low. When the junction cools to the required level (130°C typical), the PWM initiates soft start as during a normal power-up cycle. Copyright © 2011, Texas Instruments Incorporated 19 TPS40322 SLUSAF8 – JUNE 2011 www.ti.com LAYOUT CONSIDERATIONS Power Stage A synchronous BUCK power stage has two primary current loops. The input current loop carries high AC discontinuous current while the output current loop carries high DC continuous current. The input current loop includes the input capacitors, the main switching MOSFET, the inductor, the output capacitors and the ground path back to the input capacitors. To maintain the loop as small as possible, it is generally good practice to place some ceramic capacitance directly between the drain of the main switching MOSFET and the source of the synchronous rectifier (SR) through a power ground plane directly under the MOSFETs. The output current loop includes the SR MOSFET, the inductor, the output capacitors, and the ground return between the output capacitors and the source of the SR MOSFET. As with the input current loop, the ground return between the output capacitor ground and the source of the SR MOSFET should be routed under the inductor and SR MOSFET to minimize the power loop area. The SW node area should be as small as possible to reduce the parasitic capacitance and minimize the radiated emissions. The gate drive loop impedance (HDRV-gate-source-SW and LDRV-gate-source- GND) should be kept to as low as possible. The HDRV and LDRV connections should widen to 20 mils as soon as possible out from the device pin. Device Peripheral The TPS40322 provides separate signal ground (AGND) and power ground (PGND1 and PGND2) pins. It is required to properly separate the circuit grounds. The return path for the pins associated with the power stage should be through PGND. The other pins (especially for those sensitive pins such as FB1, FB2, RT, ILIM1, and ILIM2) should be through the low noise AGND. The AGND and PGND planes are suggested to be connected at the output capacitor with single 20-mil trace. A minimum 0.1-µF ceramic capacitor must be placed as close to the VDD pin and AGND as possible with at least 15-mil wide trace from the bypass capacitor to the AGND. A minimum value of 3.3-µF ceramic capacitor should be connected from BP6 to PGND, placed as close to the BP6 pin as possible. When DCR sensing method is applied, the sensing resistor should be placed close to the SW node and connected to the inductor with a Kelvin connection. The sensing traces from the power stage to the chip should be away from the switching components. The sensing capacitor should be placed very close to the CS+ and CS- pins for each output. The frequency setting resistor should be placed as close to RT pin and AGND as possible. In multi-phase mode, the ILIM2/VSNS and EN2/SS2/GSNS pins should be directly connected to the point of load where the voltage regulation is required. A parallel pair of 10-mil traces connects the regulated voltage back to the chip. They should be away from the switching components. The PowerPAD™ should be electrically connected to AGND. PowerPAD™ Layout The PowerPAD™ package provides low thermal impedance for heat removal from the device. The PowerPAD™ derives its name and low thermal impedance from the large bonding pad on the bottom of the device. The circuit board must have an area of solder-tinned-copper underneath the package. The dimensions of this area depend on the size of the PowerPAD™ package. Thermal vias connect this area to internal or external copper planes and should have a drill diameter sufficiently small so that the via hole is effectively plugged when the barrel of the via is plated with copper. This plug is needed to prevent wicking the solder away from the interface between the package body and the solder-tinned area under the device during solder reflow. Drill diameters of 0.33 mm (13 mils) works well when 1-oz. copper is plated at the surface of the board while simultaneously plating the barrel of the via. If the thermal vias are not plugged when the copper plating is performed, then a solder mask material should be used to cap the vias with a diameter equal to the via diameter plus 0.1 mm minimum. This capping prevents the solder from being wicked through the thermal vias and potentially creating a solder void under the package. Refer to PowerPAD™ Thermally Enhanced Package (TI LIterature Number SLMA002) for more information on the PowerPAD™ package. 20 Copyright © 2011, Texas Instruments Incorporated TPS40322 SLUSAF8 – JUNE 2011 www.ti.com TPS40322 Design Example 1 Dual-Output Configuration from 12-V Nominal to 1.2-V and 1.8-V DC-to-DC Converter Using the TPS40322 The following example illustrates the design process and component selection for a dual output synchronous buck converter using the TPS40322 controller. The design goal parameters are listed in Table 2. Table 2. TPS40322 Dual Output Design Example Specification PARAMETER TEST CONDITION MIN NOM 8 12 MAX UNIT INPUT CHARACTERSTICS VIN Input voltage VIN(ripple) Input ripple IOUT1 = IOUT2 = 10 A 15 V 0.25 V OUTPUT 1 CHARACTERSTICS Output voltage IOUT1(min) ≤ IOUT1 ≤ IOUT1(max) Line regulation VIN(min) ≤ VIN ≤ VIN(max) 0.5% Load regulation IOUT1(min) ≤ IOUT1 ≤ IOUT1(max) 0.5% VRIPPLE1 Output ripple IOUT1 = IOUT1(max) VOVER1 Output overshoot ΔIOUT1 = 5 A 40 VUNDER1 Output undershoot ΔIOUT1 = 5A 40 IOUT1 Output current VIN(min) ≤ VIN ≤ VIN(max) ISCP1 Short circuit current trip point VOUT1 1.2 V 24 0 mV mV mV 10 15 A A OUTPUT 2 CHARACTERSTICS VOUT2 Output voltage IOUT2(min) ≤ IOUT2 ≤ IOUT2(max) Line regulation VIN(min) ≤ VIN ≤ VIN(max) 0.5% 0.5% Load regulation IOUT2(min) ≤ IOUT2 ≤ IOUT2(max) VRIPPLE2 Output ripple IOUT2 = IOUT2(max) VOVER2 Output overshoot ΔIOUT2 = 5 A VUNDER2 Output undershoot ΔIOUT2 = 5 A IOUT2 Output current VIN(min) ≤ VIN ≤ VIN(max) ISCP2 Short circuit current trip point 1.8 V 36 40 mV 40 0 mV mV 10 A 15 A 2 ms GENERAL CHARACTERSTICS tSS Soft-start time VIN = 12 V η Efficiency VIN = 12 V, IOUT1= IOUT2 = 10 A fSW Switching frequency 88% 500 kHz Design Procedure Equations and calculations are shown regarding VOUT1. VOUT2 values can be calculated using similar equations. Selecting a Switching Frequency To maintain acceptable efficiency and meet minimum on-time requirements, a 500kHz switching frequency is selected. Inductor Selection (L1) Synchronous BUCK power inductors are typically sized for approximately 20% - 40% peak-to-peak ripple current (IRIPPLE). Given a target ripple current of 30%, the required inductor size, at maximum rated output current, can be calculated using Equation 8. VIN(max) - VOUT1 VOUT1 1 15 V - 1.2 V 1.2 V 1 L1 » ´ ´ = ´ ´ = 0.736 mH 0.3 ´ IOUT1 VIN(max) fSW 0.3 ´ 10 A 15 V 500kHz (8) Selecting a standard, readily available inductor, with a rated inductance is 0.88 µH at 10 A, IRIPPLE1 = 2.5 A Copyright © 2011, Texas Instruments Incorporated 21 TPS40322 SLUSAF8 – JUNE 2011 www.ti.com The RMS current through the inductor is approximated by the equation: 2 1 ´I 12 RIPPLE1 (I ( ) ) + ( IL1(rms ) = L1 avg 2 ) 2 = (IOUT1 )2 + (112 ´ IRIPPLE1 ) 2 = 102 + (112 ´ 2.5 ) = 10.026 A (9) Output Capacitor Selection (C10 through C16) The selection of the output capacitor is typically driven by the output transient response requirement. Equation 10and Equation 11 over-estimate the voltage deviation to account for delays in the loop bandwidth and can be used to determine the required output capacitance: 2 VOVER1 < DIOUT1 DI DI ´ L1 (DIOUT1 ) ´ L1 ´ Dt = OUT1 ´ OUT1 = COUT1 COUT1 VOUT1 VOUT1 ´ COUT1 (10) 2 VUNDER1 < (DIOUT1 ) ´ L1 DIOUT1 DI DI ´ L1 ´ Dt = OUT1 ´ OUT1 = COUT1 COUT1 VIN - VOUT1 (VIN - VOUT1 )´ COUT1 (11) When VIN(min) > 2 x VOUT1, use the overshoot equation, VOVER1, to calculate minimum output capacitance. When VIN(min) < 2 x VOUT1 use Equation 11, VUNDER1, to calculate minimum output capacitance. In this design example, VIN(min) is much larger than 2 x VOUT1 so Equation 12 is used to determine the required minimum output capacitance. COUT1(min) = (DIOUT1 )2 ´ L1 VOUT ´ VOVER1 = 52 ´ 0.88 mH = 458 mF 1.2 ´ 40mV (12) With a minimum capacitance, the maximum allowable ESR is determined by the maximum ripple voltage and is approximated by Equation 13. æ ö IRIPPLE1 æ ö 2.5 A VRIPPLE1 - ç ÷ 24mV - ç ÷ VRIPPLE1 - VRIPPLE(cap) è 8 ´ COUT1 ´ fSW ø = è 8 ´ 458 mF ´ 500kHz ø = 9mW = ESRMAX = IRIPPLE1 IRIPPLE1 2.5 A (13) Two 220-µF, 4-V, aluminum electrolytic capacitors were chosen for load response requirements. Additionally two 0805 10-µF, X7R, along with two 0603, 3.3-µF X5R, and one 1-µF, X5R ceramic capacitors are selected for low ESR and high frequency decoupling. Peak Current Rating of Inductor With the output capacitance known, it is possible to calculate the charge current during start-up and determine the minimum saturation current rating for the inductor. The start-up charging current is approximated using Equation 14. ´ COUT1 1.2 V ´ (2 ´ 220 mF + 2 ´ 10 mF + 2 ´ 3.3 mF + 1mF ) V = = 0.281A ICHARGE = OUT1 tSS 2ms 1 IL1(peak ) = IOUT1(max) + ( 2 ´ IRIPPLE1 (14) 1 )+ ICHARGE = 10 A + ( 2 ´ 2.5A )+ 0.281A = 11.53 A (15) Table 3. Inductor Requirements Summary PARAMETER VALUE UNITS 0.88 µH RMS current (thermal rating) 10.026 A Peak current (saturation rating) 11.53 A L1 Inductance IL1_RMS IL1_PEAK 22 Copyright © 2011, Texas Instruments Incorporated TPS40322 SLUSAF8 – JUNE 2011 www.ti.com A 744314110 from Wurth-Midcom with 1.1-µH zero current inductance is selected. Inductance for this part is 0.88-µH at 10 A bias. This 15-A, 3.15 mΩ inductor exceeds the minimum inductor ratings in a 7 mm x 7 mm package. Input Capacitor Selection (C3 through C6) The input voltage ripple is divided between the capacitance and ESR of the input capacitor. For this design VRIPPLE(cap) = 200 mV and VRIPPLE(esr) = 50 mV. The minimum capacitance and maximum ESR are estimated using Equation 16. IOUT1 ´ VOUT1 10 A ´ 1.2 V = = 15 mF CIN1(min) = VRIPPLE(cap) ´ VIN(min) ´ fSW 200mV ´ 8 V ´ 500kHz (16) ESRMAX = VRIPPLE(esr) 1 ´I 2 RIPPLE1 IOUT1 + ( = ) 50mV = 4.44mW 11.25 A (17) The RMS current in the input capacitors is estimated using Equation 18. IRMS(cin1) = IOUT1 ´ D ´ (1 - D ) = 10 A ´ 0.15 ´ (1 - 0.15) = 3.57 A (18) V D = OUT1 VIN(min) (19) To achieve these goals, two 0805, 10-µF capacitors, one 0605, 1.0-µF capacitor and one 0402, 0.1-µF X5R ceramic capacitor are combined at the input. MOSFET Selection (Q1) Texas Instruments CSD86330, 20-A power block device was chosen. This device incorporates the high-side and low-side MOSFETs in a single 3 mm x 3 mm package. The high-side MOSFET has an on-resistance (RDS(on)) of 8.8 mΩ, while the low-side on-resistance (RDS(on)) is 4.6 mΩ, both at 4.5 V gate voltage. A 5.11-Ω gate resistor is used on the HDRV pin on each device for added noise immunity. ILIM Resistor (R2) The output current is sensed across the DCR of the L1 output inductor. An RC combination having a time constant equal to that of the L1 inductance and the DCR is used to extract the current information as a voltage. A standard capacitor value of 0.1-µF is used. The resistor, R13, can be calculated using Equation 20. L1 0.88 mH = = 2.8kW R13 = C ´ VDCR 0.1mF ´ 3.15mW (20) A standard 3.09-kΩ resistor was selected. This design limits the maximum voltage drop across the current sense inputs, VCS(max), to 60 mV. If the voltage drop across the DCR of the inductor is greater than VCS(max), after allowing for 30% overshoot spikes and a 20% variation in the DCR value, then a resistor is added to divide the voltage down to 60 mV. The divider resistor, R15, is calculated by Equation 21. R13 ´ VCS(max ) R15 = VDCR - VCS(max ) ) ( where VDCR = (DCR ´ 1.2 )´ IL(peak ) ´ 1.3 ( ) (22) (22) The TPS40322 uses the negative drop across the low-side FET at the end of the “OFF” time to measure the inductor current. Allowing for 20% over the minimum current limit for transient recovery and 20% rise in RDS(on)Q2 for self-heating of the MOSFET, the voltage drop across the low-side FET at current limit is given by Equation 23. Copyright © 2011, Texas Instruments Incorporated 23 TPS40322 SLUSAF8 – JUNE 2011 www.ti.com éæ ù éæ ù I 2.5 A ö ö VOC = êç IOUT1 + RIPPLE1 ÷ ´ 1.2ú ´ (DCR ´ 1.2 ) = êç 10 A + ÷ ´ 1.2ú ´ (3.15mW ´ 1.2 ) = 51.05mV 2 2 ø ø ëè û ëè û (23) The current limit resistor is calculated using the minimum ILIM programming current, IILIM(min), the maximum current sense amplifier gain, ACS(max), and taking into account the current sense amplifier minimum input offset voltage, VOS(min). (V = OC RILIM ) ´ A CS(max ) - VOS(min ) IILIM(min) 51.05mV ´ 16 V )- (-3mV ) ( V = = 86.29kW » 86.6kW 9.5 mA (24) Feedback Divider (R10, R14) The TPS40322 controller uses a full operational amplifier with an internally fixed 0.600-V reference. Tha value for R10 is selected between 10-kΩand 50-kΩ for a balance of feedback current and noise immunity. With the R10 resistor set to 20-kΩ, the output voltage is programmed with a resistor divider given by Equation 25. VFB ´ R10 0.600 V ´ 20.0kW R14 = = = 20kW VOUT1 - VFB 1.2 V - 0.600 V (25) Compensation: (R11, R12, C17, C19, C21) Using the TPS40k Loop Stability Tool for an 85-kHz bandwidth and 50° of phase margin with an R10 value of 20.0 kΩ, and measuring the theoretical results in the laboratory and modifying accordingly for system optimization yields the following values. • C21 = 10 pF • C17 = 220 pF • C19 = 470 pF • R12 = 4.42 kΩ • R11 = 82.5 kΩ Boot-Strap Capacitor (C7) To ensure proper charging of the high-side FET gate, limit the ripple voltage on the boost capacitor to < 100 mV. QG1 7nC CBOOST = = = 70nF » 100nF VBOOT(ripple ) 100mV (26) General Device Components Synchronization (SYNC Pin) The SYNC pin can be left open for independent dual outputs. RT Resistor (R6) The desired switching frequency is programmed by the current through RRT to GND. the value of RRT is calculated using Equation 27. RRT = 209 209 = = 40kW » 40.2kW fSW 500kHz (27) Differential Amplifier Out (DIFFO Pin) In dual output configuration the DIFFO pin is not used and must remain open (unconnected). EN/SS Timing Capacitors (C8) The soft-start capacitor provides smooth ramp of the error amplifier reference voltage for controlled start-up. The soft-start capacitor is selected using Equation 28. 24 Copyright © 2011, Texas Instruments Incorporated TPS40322 SLUSAF8 – JUNE 2011 www.ti.com t ´I 2ms ´ 10 mA CSS = SS SS = » 33nF VFB 0.6 V (28) Power Good (PG1, PG2 Pins) PG1 and PG2 can each be pulled up to BP6 through a 100-kΩ resistor, or remain not-connected. For sequencing the start-up of output 1 before output 2, connect PG1 to EN2/SS2; for sequencing the startup of output 2 before output 1, connect PG2 to EN1/SS1. Phase Set (PHSET Pin) The PHSET pin can be connected to ground or connected to the BP6 pin for connections to ground (GND). UVLO Programming Resistors (R1 and R3) The UVLO hysteresis level is programmed by R1 with Equation 29 and Equation 30. VUVLO(on ) - VUVLO(off ) 8 V - 7 V = = 66.7kW » 68.1kW RUVLO(hys ) = IUVLO 15 mA RUVLO(set ) > RUVLO(hys ) ´ VUVLO(max) (VUVLO(on _ min) - VUVLO(max) ) = 68.1kW 1.25 V = 12.6kW » 12.7kW 8.0 ( V - 1.25 V ) (29) (30) VDD Bypass Capacitor (C2) As shown in the ELECTRICAL CHARACTERISTICS table, a 0.1-µF, 50-V, X7R capacitor has been selected for VDD bypass. VBP6 Bypass Capacitor (C18) Per the TPS40322 datasheet, select a 3.3-µF (or greater) low ESR capacitor for BP6. For this design a 3.3-µF, X5R ceramic capacitor was chosen Schematic Figure 23 shows the dual output converter schematic for this design example Copyright © 2011, Texas Instruments Incorporated 25 TPS40322 SLUSAF8 – JUNE 2011 + + + + + www.ti.com Figure 23. Design Example 1, Dual Output Converter Schematic 26 Copyright © 2011, Texas Instruments Incorporated TPS40322 SLUSAF8 – JUNE 2011 www.ti.com Typical Performance Characteristics 95 95 VOUT = 1.2 V 90 85 80 80 Efficiency (%) 85 70 65 60 50 0 1 2 3 4 5 6 7 Output Current (A) 8 9 65 55 50 10 VIN = 8 V VIN = 12 V VIN = 15 V VOUT = 1.8 V 0 1 2 G001 Figure 24. Efficiency vs Load Current (8 V to 15 V to 1.2 V at 10 A, Design Example 1) 3 4 5 6 7 Output Current (A) 8 9 10 G001 Figure 25. Efficiency vs Load Current (8 V to 15 V to 1.8 V at 10 A, Design Example 1) 100 225.0 100 225.0 80 180.0 80 180.0 60 135.0 60 135.0 40 90.0 40 90.0 20 45.0 20 45.0 0 0.0 0 0.0 −20 −40 −60 100 Gain Phase 1000 10000 Frequency (Hz) 100000 −45.0 −20 −90.0 −40 −135.0 1000000 Figure 26. Design Example 1 Loop Response VIN = 12 V, VOUT1 = 1.2 V, IOUT1 = 10 A, 80-kHz Bandwidth, 50° Phase Margin Copyright © 2011, Texas Instruments Incorporated Phase (°) Gain (dB) 70 60 VIN = 8 V VIN = 12 V VIN = 15 V 55 75 −60 100 Phase (°) 75 Gain (dB) Efficiency (%) 90 −45.0 −90.0 Gain Phase 1000 10000 Frequency (Hz) 100000 −135.0 1000000 Figure 27. Design Example 1 Loop Response VIN = 12 V, VOUT2 = 1.8 V, IOUT2 = 10 A, 80-kHz Bandwidth, 50° Phase Margin 27 TPS40322 SLUSAF8 – JUNE 2011 www.ti.com Figure 28 shows the switching waveform, VIN = 12 V, IOUT1 = IOUT2 = 10 A, Ch.1 = HDRV1, Ch.2 = LDRV1, Ch.3 = VOUT1 ripple. The high-frequency noise is caused by parasitic inductive and capacitive elements interacting with the high energy, rapidly switching power elements resulting in ringing at the transition points. Capacitive filtering at the load input will successfully attenuate these noise spikes. Figure 28. Design Example 1 Switching Waveform 28 Copyright © 2011, Texas Instruments Incorporated TPS40322 SLUSAF8 – JUNE 2011 www.ti.com Table 4. Design Example 1, Dual-Output List of Materials REFERENCE DESIGNATOR QTY DESCRIPTION PART NUMBER MFR C1 1 Capacitor, Aluminum, 100 µF, 35 V, ±20%, 0.328 x 0.328 inch EEV-FK1V101GP Panasonic - ECG C2, C7, C20, C26, C39 5 Capacitor, Ceramic, 0.1 µF, 50 V, X7R, ±10%, 0603 Std Std C3, C35 2 Capacitor, Ceramic, 0.1 µF, 25 V, X5R, ±10%, 0402 Std Std C4, C36 2 Capacitor, Ceramic, 1.0 µF, 25 V, X7R, ±10%, 0603 Std Std C5, C6, C37, C38 4 Capacitor, Ceramic, 10 µF, 25 V, X5R, ±10%, 0805 Std Std C8, C25 2 Capacitor, Ceramic, 33 nF, 16 V, X7R, ±10%, 0603 Std Std C9, C19, C22, C34 4 Capacitor, Ceramic, 470 pF, 25 V, C0G, NP0, ±5%, 0603 Std Std C10, C27 2 Capacitor, Ceramic, 1.0 µF, 6.3 V, X5R, ±10%, 0402 Std Std C11, C12, C18, C28, C29 5 Capacitor, Ceramic, 3.3 µF, 10 V, X5R, ±10%, 0603 C1608X5R1A335K TDK Corporation C13, C14, C30, C31 4 Capacitor, Ceramic, 10 µF, 6.3 V, X7R, ±10%, 0805 Std Std C15, C16, C32, C33 4 Capacitor, Polymer Aluminum, 220 µF, 4 V, ±20%, 5m ESR EEF-SE0G221ER Panasonic - ECG C17, C23 2 Capacitor, Ceramic, 220 pF, 50 V, C0G, NP0, ±5%, 0603 Std Std C21, C24 2 Capacitor, Ceramic, 10 pF, 50 V, C0G, NP0, ±5%, 0603 Std Std C40 1 Capacitor, Ceramic, 1.0 nF, 25 V, C0G, NP0, ±5%, 0603 Std Std L1, L2 2 Inductor, Power Choke, 1.1 µH, ±20%, 3.15mΩ, 7.0 x 6.9 mm 744314110 Wurth Elektronik Q1, Q2 2 MOSFET, Synchronous Buck NexFET Power Block, QFN-8 POWER CSD86330Q3D Texas Instruments R1 1 Resistor, Chip, 68.1 kΩ, 1/10W, ±1%, 0603 Std Std R2, R21 2 Resistor, Chip, 86.6 kΩ, 1/10W, ±1%, 0603 Std Std R3 1 Resistor, Chip, 12.7 kΩ, 1/10W, ±1%, 0603 Std Std R4, R5, R22 3 Resistor, Chip, 1.00 Ω, 1/10W, ±1%, 0603 Std Std R6 1 Resistor, Chip, 40.2 kΩ, 1/10W, ±1%, 0603 Std Std R7, R24 2 Resistor, Chip, 49.9 Ω, 1/10W, ±1%, 0603 Std Std R8, R17 2 Resistor, Chip, 5.11 Ω, 1/8W, ±1%, 0805 Std Std R9, R16 2 Resistor, Chip, 0 Ω, 1/10W, ±1%, 0603 Std Std R10, R14, R19, R27 4 Resistor, Chip, 20.0 kΩ, 1/10W, ±1%, 0603 Std Std R11, R18 2 Resistor, Chip, 82.5 kΩ, 1/10W, ±1%, 0603 Std Std R12, R23 2 Resistor, Chip, 1.62 kΩ, 1/10W, ±1%, 0603 Std Std R13 1 Resistor, Chip, 3.09 kΩ, 1/10W, ±1%, 0603 Std Std R15 1 Resistor, Chip, 29.4 kΩ, 1/10W, ±1%, 0603 Std Std R20, R30 2 Resistor, Chip, 5.11 Ω, 1/10W, ±1%, 0603 Std Std R25 1 Resistor, Chip, 10.0 kΩ, 1/10W, ±1%, 0603 Std Std R26 1 Resistor, Chip, 3.24 kΩ, 1/10W, ±1%, 0603 Std Std R28, R29 2 Resistor, Chip, 100 kΩ, 1/10W, ±1%, 0603 Std Std 1 IC, TPS40322 Dual Synchronous Buck Controller, QFN-32 TPS40322RHB Texas Instruments U1 Copyright © 2011, Texas Instruments Incorporated 29 TPS40322 SLUSAF8 – JUNE 2011 www.ti.com TPS40322 Design Example 2 Two-Phase Single Output Configuration from 12-V nominal to 1.2-V DC-to-DC Converter Using the TPS40322 The following example shows the schematic, waveforms, and components for a two-phase single output synchronous buck converter using the TPS40322 controller. The design goal parameters are given in Table 5. Table 5. TPS40322 Design Example Specification PARAMETER TEST CONDITION MIN NOM 4.5 MAX VIN Input voltage 15 VOUT Output voltage IOUT(min) ≤ IOUT ≤ IOUT(max) Line regulation VIN(min) ≤ VIN ≤ VIN(max) 0.5% 0.5% 1.2 Load regulation IOUT(min) ≤ IOUT ≤ IOUT(max) VRIPPLE Output ripple IOUT1 = IOUT1(max) VOVER Output overshoot ΔIOUT1 = 5 A 40 VUNDER Output undershoot ΔIOUT1 = 5A 40 IOUT Output current VIN(min) ≤ VIN ≤ VIN(max) tSS Soft-start time VIN = 12 V η Efficiency VIN = 12 V, IOUT1= IOUT2 = 10 A fSW Switching frequency 30 mV mV mV 10 2 V V 12 0 UNIT A ms 88% 500 kHz Copyright © 2011, Texas Instruments Incorporated TPS40322 SLUSAF8 – JUNE 2011 www.ti.com + + + + + + + + + + Figure 29 shows the two-phase converter schematic described in design example 2. Figure 29. Design Example 2, Two-Phase Converter Schematic Copyright © 2011, Texas Instruments Incorporated 31 TPS40322 SLUSAF8 – JUNE 2011 www.ti.com Design Example 2 Characterization 1.1955 SW2 (10 V/div) 1.1950 Output Voltage (V) 1.1945 1.1940 SW1 (10 V/div) 1.1935 1.1930 1.1925 IL1 (5 A/div) IL2 (5 A/div) 1.1920 VOUT = 30 A 1.1915 0 Figure 30. Steady-State Switching and Current Sharing 2 4 6 8 10 Input Voltage (µV) 12 14 16 G001 Figure 31. Line Regulation 1.2030 1.2020 Output Voltage (V) 1.2010 1.2000 1.1990 1.1980 1.1970 1.1960 0 5 10 15 20 Input Current (A) 25 30 G001 Figure 32. Load Regulation 32 Copyright © 2011, Texas Instruments Incorporated TPS40322 SLUSAF8 – JUNE 2011 www.ti.com Table 6. TPS40322 Design Example 2, Two-Phase, Single Output Bill of Materials REFERENCE DESIGNATOR QTY DESCRIPTION PART NUMBER MFR C1, C2, C3, C31, C32, C33 6 Capacitor, Ceramic, 22 µF, 25V, X5R, ±20%, 1210 Std Std C4, C18, C28, C30 4 Capacitor, Ceramic, 1 µF, 50V, X7R, ±10%, 0603 Std Std C5, C6, C7, C22, C29 5 Capacitor, Ceramic, 0.1 uF, 50V, X7R, ±10%, 0603 Std Std C8, C21 2 Capacitor, Ceramic, 6.8 nF, 50V, X7R, ±10%, 0805 Std Std C9 1 Capacitor, Ceramic, 2.2 nF, 16V, X7R, ±10%, 0603 Std Std C10, C11, C12, C13, C23, C24, C25, C26 8 Capacitor, Polymer Aluminum, 220 µF, 4V, ±20%, 5m ESR EEFSE0G221R Panasonic - ECG C14, C27 2 Capacitor, Ceramic, 22 µF, 6.3 V, X5R, ±10%, 0805 Std Std C15 1 Capacitor, Ceramic, 8.2 nF, 16 V, X7R, ±10%, 0603 Std Std C16 1 Capacitor, Ceramic, 330 pF, 16 V, X7R, ±10%, 0603 Std Std C17 1 Capacitor, Ceramic, 22 nF, 50 V, X7R, ±10%, 0603 Std Std C19, C20 2 Capacitor, Ceramic, 4.7 µF, 16 V, X7R, ±10%, 0805 Std Std C38, C39 2 Capacitor, Aluminum, 100 µF, 25 V, ±20%, F8 ECE-V1EA101XP Panasonic - ECG L1, L2 2 Inductor, SMT, 0.47 µH, ±20%, 1.2 mΩ, 0.512 x 0.571" IHLP5050FDERR47M01 Vishay/Dale Q1, Q4 2 MOSFET, N-channel, 30 V, 30 A, 8mΩ, 5-LFPAK RJK0305 Renesas Electronics Q2, Q3 2 MOSFET, N-channel, 30 V, 60 A, 2.1 mΩ, 5-LFPAK RJK0328 Renesas Electronics R1 1 Resistor, Chip, 42 kΩ, 1/10W, ±1%, 0603 Std Std R2 1 Resistor, Chip, 100 kΩ, 1/10W, ±1%, 0603 Std Std R3, R19 2 Resistor, Chip, 4.7 kΩ, 1/10W, ±1%, 0603 Std Std R4 1 Resistor, Chip, 38.5 kΩ, 1/10W, ±1%, 0603 Std Std R5 1 Resistor, Chip, 49.9 Ω, 1/10W, ±1%, 0603 Std Std R6, R8, R16 3 Resistor, Chip, 10 kΩ, 1/10W, ±1%, 0603 Std Std R7, R27, R28, R29, R30 5 Resistor, Chip, 0 Ω, 1/10W, ±1%, 0603 Std Std R9 1 Resistor, Chip, 511 Ω, 1/10W, ±1% Std Std R10, R17 1 Resistor, Chip, 1.00 Ω, 1/8W, ±1%, 0805 Std Std R11, R18 2 Resistor, Chip, 5.11 Ω, 1/10W, ±1% 0603 603 Std R12, R13 2 Resistor, Chip, 51 Ω, 1/10W, ±1%, 0603 Std Std R14 1 Resistor, Chip, 3.32 kΩ, 1/10W, ±1%, 0603 Std Std R15 1 Resistor, Chip, 40 kΩ, 1/10W, ±1%, 0603 Std Std R26, R31 2 Resistor, Chip, 2 Ω, 1/10W, ±1%, 0603 Std Std R20, R21, R22, R23, R24, R25, 0 not used Std Std U1 1 Dual synchronous buck controller, QFN-32 TPS40322RHB Texas Instruments Copyright © 2011, Texas Instruments Incorporated 33 PACKAGE OPTION ADDENDUM www.ti.com 20-Jun-2011 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Qty Eco Plan (2) Lead/ Ball Finish MSL Peak Temp (3) TPS40322RHBR ACTIVE QFN RHB 32 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS40322RHBT ACTIVE QFN RHB 32 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR Samples (Requires Login) (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. In no event shall TI's liability arising out of such information exceed the total purchase price of the TI part(s) at issue in this document sold by TI to Customer on an annual basis. Addendum-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 17-Jun-2011 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant TPS40322RHBR QFN RHB 32 3000 330.0 12.4 5.3 5.3 1.5 8.0 12.0 Q2 TPS40322RHBT QFN RHB 32 250 180.0 12.4 5.3 5.3 1.5 8.0 12.0 Q2 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 17-Jun-2011 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) TPS40322RHBR QFN RHB 32 3000 346.0 346.0 29.0 TPS40322RHBT QFN RHB 32 250 190.5 212.7 31.8 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. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where mandated by government requirements, testing of all parameters of each product is not necessarily performed. TI assumes no liability for applications assistance or customer product design. Customers are responsible for their products and applications using TI components. To minimize the risks associated with customer products and applications, customers should provide adequate design and operating safeguards. TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right, or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information published by TI regarding third-party products or services does not constitute a license from TI to use such products or services or a warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual property of the third party, or a license from TI under the patents or other intellectual property of TI. Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive business practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional restrictions. Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not responsible or liable for any such statements. TI products are not authorized for use in safety-critical applications (such as life support) where a failure of the TI product would reasonably be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governing such use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may be provided by TI. Further, Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products in such safety-critical applications. TI products are neither designed nor intended for use in military/aerospace applications or environments unless the TI products are specifically designated by TI as military-grade or "enhanced plastic." Only products designated by TI as military-grade meet military specifications. Buyers acknowledge and agree that any such use of TI products which TI has not designated as military-grade is solely at the Buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use. TI products are neither designed nor intended for use in automotive applications or environments unless the specific TI products are designated by TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designated products in automotive applications, TI will not be responsible for any failure to meet such requirements. Following are URLs where you can obtain information on other Texas Instruments products and application solutions: Products Applications Audio www.ti.com/audio Communications and Telecom www.ti.com/communications Amplifiers amplifier.ti.com Computers and Peripherals www.ti.com/computers Data Converters dataconverter.ti.com Consumer Electronics www.ti.com/consumer-apps DLP® Products www.dlp.com Energy and Lighting www.ti.com/energy DSP dsp.ti.com Industrial www.ti.com/industrial Clocks and Timers www.ti.com/clocks Medical www.ti.com/medical Interface interface.ti.com Security www.ti.com/security Logic logic.ti.com Space, Avionics and Defense www.ti.com/space-avionics-defense Power Mgmt power.ti.com Transportation and Automotive www.ti.com/automotive Microcontrollers microcontroller.ti.com Video and Imaging www.ti.com/video RFID www.ti-rfid.com Wireless www.ti.com/wireless-apps RF/IF and ZigBee® Solutions www.ti.com/lprf TI E2E Community Home Page e2e.ti.com Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265 Copyright © 2011, Texas Instruments Incorporated