TPS53211 SLUSAA9 – SEPTEMBER 2011 www.ti.com Single-Phase PWM Controller with Light-Load Efficiency Optimization FEATURES APPLICATIONS • • • • • 1 • • • • • • • • • • • • • • 1.5-V to 19-V Conversion Voltage Range 4.5-V to 14-V Supply Voltage Range Voltage Mode Control Skip Mode at Light Load for Efficiency Optimization High Precision 0.5% Internal 0.8-V Reference Adjustable Output Voltage from 0.8 V to 0.7×VIN Internal Soft-Start Supports Pre-biased Startup Supports Soft-Stop Programmable Switching Frequency from 250 kHz to 1 MHz Overcurrent Protection Inductor DCR Sensing for Overcurrent RDS(on) Sensing for Zero Current Detection Overvoltage and Undervoltage Protection Open Drain Power Good Indication Internal Bootstrap Switch Integrated High-Current Drivers Powered by VCCDR Small 3 mm x 3 mm, 16-Pin QFN Package • • • Server and Desktop Computer Subsystem Power Supplies DDR Memory and Termination Supply Distributed Power Supply General DC/DC Converter DESCRIPTION TPS53211 is a single phase PWM controller with integrated high-current drivers. It is used for 1.5 V up to 19 V conversion voltage. TPS53211 features a skip mode solution that optimizes the efficiency at light load condition without compromising the output voltage ripple. The device provides pre-biased startup, soft-stop, integrated bootstrap switch, power good function, EN/Input UVLO protection. It supports conversion voltages up to 19 V, and output voltages adjustable from 0.8 V to 0.7×VIN. The TPS53211 is available in the 3 mm × 3 mm, 16-pin, QFN package (Green RoHs compliant and Pb free) and is specified from –40°C to 85°C. VIN Power Enable Good 8 COMP 7 6 5 EN PGOOD UGATE FB BOOT 4 10 VSEN PHASE 3 LGATE 2 VCCDR 1 9 VOUT TPS53211 11 FBG 12 CSN CSP OSC VCC GND 13 14 15 16 PVCC UDG-11173 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 TPS53211 SLUSAA9 – SEPTEMBER 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 TA PACKAGE –40°C to 85°C Plastic QFN (RGT) ORDERABLE DEVICE NUMBER TPS53211RGTR TPS53211RGTT PINS 16 OUTPUT SUPPLY MINIMUM QUANTITY Tape and Reel 3000 Mini Reel 250 ECO PLAN Green (RoHS and no Pb/Br) ABSOLUTE MAXIMUM RATINGS (1) over operating free-air temperature range (unless otherwise noted) VCC, EN BOOT to PHASE Input voltage range (2) PHASE V 7.7 V –0.3 36 V dc –0.3 7.7 V transient < 200ns –5 7.7 V dc –3 26 V transient < 200ns –5 30 V –0.3 3.6 V –0.7 5.3 V VVCC ≤ 6.8 V –0.7 VCC-1.5 V –0.3 36 V –0.3 7.7 V –5 7.7 V COMP –0.3 3.6 V PGOOD –0.3 15 V GND –0.3 0.3 V FBG –0.3 0.3 UGATE Electrostatic discharge UNITS VVCC > 6.8 V CSP, CSN Ground pins 15 –0.3 FB, VSEN, OSC Output voltage range (3) MAX dc VCCDR BOOT MIN –0.3 UGATE to PHASE, LGATE dc transient < 200 ns Human Body Model (HBM) 1500 Charged Device Model (CDM) V 500 Storage junction temperature –55 150 °C Operating junction temperature –40 150 °C (1) (2) (3) 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. All voltage values are with respect to the network ground terminal unless otherwise noted. Voltage values are with respect to the SW terminal. THERMAL INFORMATION TPS53211 THERMAL METRIC (1) QFN UNITS 16 PINS θJA Junction-to-ambient thermal resistance 51.3 θJCtop Junction-to-case (top) thermal resistance 85.4 θJB Junction-to-board thermal resistance 20.1 ψJT Junction-to-top characterization parameter 1.3 ψJB Junction-to-board characterization parameter 19.4 θJCbot Junction-to-case (bottom) thermal resistance 6 (1) 2 °C/W For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953. Submit Documentation Feedback Copyright © 2011, Texas Instruments Incorporated TPS53211 SLUSAA9 – SEPTEMBER 2011 www.ti.com RECOMMENDED OPERATING CONDITIONS MIN VCC –0.1 VVCC+0.1 4.5 7 dc –0.1 34 dc –0.1 7 transient < 200ns –3 7 dc –1 24 transient < 200ns –3 28 –0.1 3.3 VCCDR Input voltage range BOOT to PHASE PHASE FB, VSEN, OSC CSP, CSN VVCC > 6.8 V –0.1 5 VVCC ≤ 6.8 V –0.1 VVCC–2 –0.1 34 –0.1 7 UGATE UGATE to PHASE, LGATE MAX 14 EN BOOT TYP 4.5 dc V –3 7 COMP –0.1 3.3 PGOOD –0.1 12 GND –0.1 0.1 FBG –0.1 0.1 Junction temperature range, TJ –40 125 °C Operating free-air temperature, TA –40 85 °C Output voltage range Ground pins Copyright © 2011, Texas Instruments Incorporated transient < 200 ns UNITS Submit Documentation Feedback V 3 TPS53211 SLUSAA9 – SEPTEMBER 2011 www.ti.com ELECTRICAL CHARACTERISTICS (1) over operating free-air temperature range, VCC = 12V, PGND = GND (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX 4.25 4.4 UNIT INPUT SUPPLY VVCC VCC supply voltage Nominal input voltage range 4.5 VPOR VCC POR threshold Ramp up; EN =’HI’ 4.1 VPORHYS VCC POR hysteresis VCCDR POR hysteresis ICC_STBY Standby current EN pin is low. VVCC= 12 V RBoot Rds(on) of the boot strap switch 12 200 V V mV 60 µA Ω 10 DRIVER SUPPLY VCCDR VCCDR Supply voltage Nominal input voltage range VPORDR VCCDR POR threshold Ramp up; EN =’HI’ VPORHYSDR VCCDR POR hysteresis VCCDR POR hysteresis ICCDR_STBY Standby current EN pin is low. VVCC = 12 V VVREF VREF Internal precision reference voltage TOLVREF VREF tolerance Close loop trim. 0°C ≤ TJ ≤ 70°C 4.5 3.15 7.0 3.32 3.50 220 V V mV 100 µA REFERENCE 0.8 –0.5% V 0.5% ERROR AMPLIFIER UGBW (2) Unity gain bandwidth 14 MHz AOL (2) Open loop gain 80 dB IFB(int) FB Input leakage current IEA(max) Output sinking and sourcing current SR (2) Slew rate Sourced from FB pin 10 nA 2.5 mA 5 V/µs ENABLE VENH EN logic high VENL EN logic low IEN EN pin current 2.2 V 600 mV 12 µA SOFT START tSS_delay Delay after EN asserting EN = ‘HI’ to “switching enabled” 1024/fSW ms tPGDELAY PGOOD startup delay time PG delay after soft-start begins 1560/fSW ms Ramp amplitude 4.5V < VVCC < 12 V RAMP 2 V PWM tMIN(on) (2) Minimum ON time DMAX (2) Maximum duty cycle 40 fSW = 1 MHz ns 70% SWITCHING FREQUENCY fSW(typ) Typical switching frequency ROSC = 61.9 kΩ fSW(min) Minumum switching frequency ROSC = 250 kΩ fSW(max) Maximum switching frequency ROSC = 14 kΩ fSW(tol) Switching frequency tolerance ROSC > 12.4 kΩ 360 400 440 kHz 250 kHz 1 MHz –20% 20% OVERCURRENT VOC_TH (1) (2) 4 CSP-CSN threshold for DCR sensing TA = 25°C 17 20 23 mV See PS pin description for levels. Ensured by design. Not production tested. Submit Documentation Feedback Copyright © 2011, Texas Instruments Incorporated TPS53211 SLUSAA9 – SEPTEMBER 2011 www.ti.com ELECTRICAL CHARACTERISTICS(1) (continued) over operating free-air temperature range, VCC = 12V, PGND = GND (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT GATE DRIVERS RHDHI (3) High-side driver sourcing resistance (VBOOT – VPH) forced to 5 V, high state 1 Ω RHDLO High-side driver sinking resistance (VBOOT – VPH) forced to 5 V, low state 0.5 Ω RLDHI Low-side driver sourcing resistance (VCCDR– GND) = 5 V, high state 0.7 Ω RLDLO Low-side driver sinking resistance VCCDR– GND = 5 V, low state 0.33 Ω 87% 89% 113% 116% POWER GOOD VPGDL PG lower threshold Measured at VSEN w/r/t VREF VPGDU PG upper threshold Measured at VSEN w//rt VREF VPGHYS PG hysteresis Measured at VSEN w/r/t VREF tOVPGDLY PG delay time at OVP Time from VSEN out of +12.5% of VREF to PG low 2.3 µs tUVPGDLY PG delay time at UVP Time from VSEN out of –12.5% of VREF to PG low 2.3 µs VINMINPG Minimum VCC voltage for valid PG at Measured at VVCC with 1 mA (or 2 mA) sink startup. current on PG pin at startup. 1 V VPGPD PG pull-down voltage Pull down voltage with 4 mA sink current IPGLK PG leakage current Hi-Z leakage current, apply 6.5 V in off state 110% 3.5% 0.2 0.4 V 7.8 12 16.2 µA 110% 113% 116% 87% 89% OUTPUT OVERVOLTAGE AND UNDERVOLTAGE PROTECTION VOVth OVP threshold Measured at the VSEN wrt. VREF. VUVth UVP threshold Measured at the VSEN wrt. VREF. tOVPDLY OVP delay time Time from VSEN out of +12.5% of VREF to OVP fault 2.3 µs tUVPDLY (3) UVP delay time Time from VSEN out of –12.5% of VREF to UVP fault 80 µs THERMAL SHUTDOWN THSD (3) THSDHYS (3) (3) Thermal shutdown Latch off controller, attempt soft-stop Thermal shutdown hysteresis Controller starts again after temperature has dropped 130 140 150 40 °C °C Ensured by design. Not production tested. Copyright © 2011, Texas Instruments Incorporated Submit Documentation Feedback 5 TPS53211 SLUSAA9 – SEPTEMBER 2011 www.ti.com DEVICE INFORMATION VCCDR 1 LGATE 2 GND VCC OSC CSP TPS53211 16 PINS (TOP VIEW) 16 15 14 13 12 CSN 11 FBG TPS53211 BOOT 4 9 FB 5 6 7 8 COMP VSEN EN 10 PGOOD 3 UGATE PHASE PIN FUNCTIONS PIN DESCRIPTION I/O NAME NO. BOOT 4 I Supply input for high-side drive (boot strap pin). Connect capacitor from this pin to SW pin COMP 8 O Error amplifier compensation terminal. Type III compensation method is generally recommended for stability. CSN 12 I Current sense negative input. CSP 13 I Current sense positive input EN 7 I Enable. FB 9 I Voltage feedback. Use for OVP, UVP and PGD determination. FBG 11 G Feedback ground for output voltage sense. GND 16 G Logic ground and low-side gate drive return. PHASE 3 O Output inductor connection to integrated power devices. LGATE 2 O Low-side gate drive output. OSC 14 O Frequency programming input. PGOOD 6 O Power good output flag. Open drain output. Pull up to an external rail via a resistor. UGATE 5 O High-side gate drive output. VCC 15 I Supply input for analog control circuitry. VCCDR 1 I/O VSEN 10 I 6 Bias voltage for integrated drivers. Output voltage sense Submit Documentation Feedback Copyright © 2011, Texas Instruments Incorporated TPS53211 SLUSAA9 – SEPTEMBER 2011 www.ti.com FUNCTIONAL BLOCK DIAGRAM VCCDR VSEN LDO + VCCDR UVLO FBG BOOT + 0.8 V 0.8 V x 87% UV/OV Threshold Generation UV UV Control Logic + 0.8 V x 113% HDRV UGATE OV PHASE OV FB XCON PWM PWM LL One-Shot Overtemp VOUT Discharge + + E/A COMP 0.8 V Ramp + LDRV LGATE SS OSC Enable Control GND VCC UVLO OCP Logic VCC TPS53211 OSC EN Copyright © 2011, Texas Instruments Incorporated CSP CSN PGOOD UDG-11172 Submit Documentation Feedback 7 TPS53211 SLUSAA9 – SEPTEMBER 2011 www.ti.com TYPICAL CHARACTERISTICS 430 Switching Frequency (kHz) 5 Supply Current (mA) 4 3 2 1 0 −40 −25 −10 5 20 35 50 65 80 Junction Temperature (°C) 95 390 380 5 20 35 50 65 80 Junction Temperature (°C) 95 110 125 G000 Figure 2. Switching Frequency vs. Junction Temperature 120 Measured at VSEN w/r/t VREF 115 Powergood Threshold (%) Powergood Hysteresis (%) 400 G000 10 8 7 6 5 4 3 2 PGOOD Lower Hysteresis PGOOD Upper Hysteresis 1 0 −40 −25 −10 5 20 35 50 65 80 Junction Temperature (°C) 95 Submit Documentation Feedback 110 105 Lower Threshold Upper Threshold 100 95 90 85 110 125 Figure 3. Power Good Hysteresis vs. Junction Temperature 8 410 370 −40 −25 −10 110 125 Figure 1. VCC Current vs. Junction Temperature 9 420 G000 80 −40 −25 −10 5 20 35 50 65 80 Junction Temperature (°C) 95 110 125 G000 Figure 4. Power Good Threshold vs. Junction Temperature Copyright © 2011, Texas Instruments Incorporated TPS53211 SLUSAA9 – SEPTEMBER 2011 www.ti.com DETAILED DESCRIPTION Introduction The TPS53211 is a single-channel synchronous buck controller with integrated high-current drivers. The TPS53211 is used for 1.5 V up to 19 V conversion voltage, and provides output voltage from 0.8 V to 0.7 VIN. It operates with programmable switching frequency ranging from 250 kHz to 1 MHz. This device employs a skip mode solution that optimizes the efficiency at light-load condition without compromising the output voltage ripple. The device provides pre-bias startup, integrated bootstrap switch, power good function, EN/Input UVLO protection. The TPS53211 is available in the 3 mm by 3mm 16-pin QFN package and is specified from –40°C to 85°C. Switching Frequency Setting The clock frequency is programmed by the value of the resistor connected from the OSC pin to ground. The switching frequency is programmable from 250 kHz to 1 MHz. The relation between the frequency and the OSC resistance is given by Equation 1. fSW = 200 + 106 (ROSC ´ 78.5 ) + 150 where • • ROSC is the resistor connected from the OSC pin to ground in kΩ fSW is the desired switching frequency in kHz (1) Soft-Start Function The soft-start function reduces the inrush current during the start-up. A slow rising reference voltage is generated by the soft-start circuitry and sent to the input of the error amplifier. When the soft-start ramp voltage is less than 800 mV, the error amplifier uses this ramp voltage as the reference. When the ramp voltage reaches 800 mV, a fixed 800 mV reference voltage is utilized for the error amplifier. The soft-start function is implemented only when VCC and VCCDR are above the respective UVLO thresholds and the EN pin is released. When the soft-start begins, the device initially waits for 1024 clock cycles and then starts to ramp up the reference. After the reference voltage begins to rise, the PGOOD signal goes high after a 1560 clock-cycle delay. UVLO Function The TPS53211 provides UVLO protection for the input supply (VCC) and driver supply (VCCDR). If the supply voltage is lower than UVLO threshold voltage minus the hysteresis, the device shuts off. When the voltage rises above the threshold voltage, the device restarts. The typical UVLO rising threshold is 4.25 V for VCC and 3.32 V for VCCDR. Hysteresis of 200 mV for VCC and 220 mV for VCCDR are also provided to prevent glitch. Overcurrent Protection The TPS53211 continuously monitors the current flowing through the inductor. The inductor DCR current sense is implemented by comparing and monitoring the difference between the CSP and CSN pins. DCR current sensing requires time constant matching between the inductor and the sensing network: L = R´C DCR (2) TPS53211 has two level OC thresholds: 20 mV and 30 mV for the voltage between the CSP and CSN pins. If the voltage between the CSP and CSN pins exceeds the 20 mV current limit threshold, an OC counter starts to increment to count the occurrence of the overcurrent events. The converter shuts down immediately when the OC counter reaches four (4). The OC counter resets if the detected current is lower than the OC threshold after an OC event. Normal operation can only be restored by cycling the VCC voltage. If the voltage between the CSP and CSN pins is higher than 30 mV, the device latches off immediately. Normal operation can be restored only by cycling the VCC voltage. Copyright © 2011, Texas Instruments Incorporated Submit Documentation Feedback 9 TPS53211 SLUSAA9 – SEPTEMBER 2011 www.ti.com The TPS53211 has thermal compensation to adjust the OCP threshold in order to reduce the influence of inductor DCR variation due to temperature change. The OCP level has a change rate of 0.35%/°C. Overvoltage and Undervoltage Protection The TPS53211 monitors the VSEN pin voltage to detect the overvoltage and undervoltage conditions. A resistor divider with the same ratio as on the FB input is recommended for the VSEN input. The overvoltage and undervoltage thresholds are set to ±13% of VOUT. When the VSEN voltage is greater than 113% of the reference, the overvoltage protection is activated. The high-side MOSFET turns off and the low-side MOSFET turns on. Normal operation can be restored only by cycling the VCC pin voltage. When the VSEN voltage is lower than 87% of the reference voltage, the undervoltage protection is triggered and the PGOOD signal goes low. After 80 µs, the controller is latched off with both the upper and lower MOSFETs turned off. After both the undervoltage and overvoltage events, the device is latched off. Normal operation can be restored only by cycling the VCC pin voltage. Power Good The TPS53211 monitors the output voltage through the VSEN. During start up, the power good signal delay after the reference begins to rise is 1560 clock cycles. After this delay, if the output voltage is within ±9.5% of the target value, PGOOD signal goes high. At steady state, if the VSEN voltage is within 113% and 87% of the reference voltage, the power good signal remains high. If VSEN voltage is outside of this limit, PGOOD pin is pulled low by the internal open drain output. The PGOOD output is an open drain and requires an external pull-up resistor. Over-Temperature Protection The TPS53211 continuously monitors the die temperature. If the die temperature exceeds the threshold value (140˚C typical), the device shuts off. When the device temperature lowers to 40˚C below the over-temperature threshold, it restarts and return to normal operation. 10 Submit Documentation Feedback Copyright © 2011, Texas Instruments Incorporated TPS53211 SLUSAA9 – SEPTEMBER 2011 www.ti.com APPLICATION INFORMATION The following example illustrates the design process and component selection for a single output synchronous buck converter using TPS53211. The schematic of a design example is shown in Figure 5. The specifications of the converter are listed in Table 1. Table 1. Specification of the Single Output Synchronous Buck Converter PARAMETER VIN Input voltage VOUT Output voltage VRIPPLE Output ripple IOUT Output current fSW Switching frequency TEST CONDITION MIN 10.8 IOUT = 20 A TYP MAX UNIT 12 13.2 V 1.05 V 1% of VOUT V 20 A 400 kHz VIN Power Enable Good 8 COMP 7 6 5 EN PGOOD UGATE FB BOOT 4 10 VSEN PHASE 3 11 FBG LGATE 2 12 CSN VCCDR 1 9 VOUT TPS53211 CSP OSC VCC GND 13 14 15 16 PVCC UDG-11173 Figure 5. Typical 12-V Input Application Circuit Output Inductor Selection Determine an inductance value that yields a ripple current of approximately 20% to 40% of maximum output current. The inductor ripple current is determined by Equation 3: IL(ripple ) = (VIN - VOUT )´ VOUT 1 ´ L ´ fSW VIN (3) The inductor requires a low DCR to achieve good efficiency, as well as enough room above peak inductor current before saturation. Copyright © 2011, Texas Instruments Incorporated Submit Documentation Feedback 11 TPS53211 SLUSAA9 – SEPTEMBER 2011 www.ti.com Output Capacitor Selection The output capacitor selection is determined by output ripple and transient requirement. When operating in CCM, the output ripple has three components: VRIPPLE = VRIPPLE(C) + VRIPPLE(ESR) + VRIPPLE(ESL) (4) VRIPPLE(C) = IL(ripple) 8 ´ COUT ´ fSW (5) VRIPPLE(ESR) = IL(ripple) ´ ESR VRIPPLE(ESL) (6) V ´ ESL = IN L (7) When a ceramic output capacitor is chosen, the ESL component is usually negligible. In the case when multiple output capacitors are used, the total ESR and ESL should be the equivalent of the all output capacitors in parallel. When operating in DCM, the output ripple is dominated by the component determined by capacitance. It also varies with load current and can be expressed as shown in Equation 8. 2 VRIPPLE(DCM) = (a ´ IL(ripple) - IOUT ) 2 ´ fSW ´ COUT ´ IL(ripple) where a= • α is the DCM On-Time coefficient and can be expressed as tON(dcm ) tON(ccm ) (8) IL VOUT a x IL(ripple) VRIPPLE IOUT t1 axT UDG-11174 Figure 6. DCM VOUT Ripple Calculation 12 Submit Documentation Feedback Copyright © 2011, Texas Instruments Incorporated TPS53211 SLUSAA9 – SEPTEMBER 2011 www.ti.com Input Capacitor Selection The selection of input capacitor should be determined by the ripple current requirement. The ripple current generated by the converter needs to be absorbed by the input capacitors as well as the input source. The RMS ripple current from the converter can be expressed as: IIN(ripple ) = IOUT ´ D ´ (1 - D ) where • V D = OUT VIN D is the duty cycle and can be expressed as (9) To minimize the ripple current drawn from the input source, sufficient input decoupling capacitors should be placed close to the device. The ceramic capacitor is recommended due to the inherent low ESR and low ESL. The input voltage ripple can be calculated as below when the total input capacitance is determined: ´D I VIN(ripple ) = OUT fSW ´ CIN (10) Output Voltage Setting Resistors Selection The output voltage is programmed by the voltage-divider resistor, R1 and R2 shown in Figure 7. R1 is connected between FB pin and the output, and R2 is connected between the FB pin and FBG. The recommended value for R1 is between 1 kΩ and 5 kΩ. Determine R2 using Equation 11. æ ö 0.8 R1 = ç ÷ ´ R1 ç (VOUT - 0.8 ) ÷ è ø (11) Compensation Design The TPS53211 employs voltage mode control. To effectively compensation the power stage and ensures fast transient response, Type III compensation is typically used. The control to output transfer function can be described in Equation 12. 1 + s ´ COUT ´ ESR GCO = 4 ´ æ ö L + COUT ´ (ESR + DCR) ÷ + s2 ´ L ´ COUT 1+ s ´ ç è DCR + RLOAD ø (12) The output LC filter introduces a double pole, calculated in Equation 13. 1 fDP = 2 ´ p ´ L ´ COUT (13) The ESR zero of can be calculated calculated in Equation 14 1 fESR = 2 ´ p ´ ESR ´ COUT Copyright © 2011, Texas Instruments Incorporated (14) Submit Documentation Feedback 13 TPS53211 SLUSAA9 – SEPTEMBER 2011 www.ti.com Figure 7 shows the configuration of Type III compensation and typical pole and zero locations. Equation 15 through Equation 17 describe the compensator transfer function and poles and zeros of the Type III network. (1 + s ´ C1 ´ (R1 + R3 ))(1 + s ´ R4 ´ C2 ) GEA = æ C ´C ö (s ´ R1 ´ (C2 + C3 ))´ (1 + s ´ C1 ´ R3 )´ ç 1 + s ´ R4 C 2 + C3 ÷ è 2 3 ø (15) 1 fZ1 = 2 ´ p ´ R 4 ´ C2 (16) 1 1 fZ2 = @ 2 ´ p ´ (R1 + R3 ) ´ C1 2 ´ p ´ R1 ´ C1 (17) C3 C1 C2 R4 Gain (dB) R1 R3 COMP VREF R2 + UGD-11176 fZ1 fZ2 fP2 fP3 Frequency UDG-11175 Figure 7. Type III Compensation Network Configuration Figure 8. Type III Compensation Network Waveform fP1 = 0 (18) 1 fP2 = 2 ´ p ´ R3 ´ C1 (19) fP3 = 1 1 @ æ C2 ´ C3 ö 2 ´ p ´ R 4 ´ C3 2 ´ p ´ R4 ´ ç ÷ è C2 + C3 ø (20) The two zeros can be placed near the double pole frequency to cancel the response from the double pole. One pole can be used to cancel ESR zero, and the other non-zero pole can be placed at half switching frequency to attenuate the high frequency noise and switching ripple. Suitable values can be selected to achieve a compromise between high phase margin and fast response. A phase margin higher than 45 degrees is required for stable operation. 14 Submit Documentation Feedback Copyright © 2011, Texas Instruments Incorporated PACKAGE OPTION ADDENDUM www.ti.com 12-Oct-2011 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Qty Eco Plan (2) Lead/ Ball Finish MSL Peak Temp (3) TPS53211RGTR ACTIVE QFN RGT 16 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS53211RGTT ACTIVE QFN RGT 16 250 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. 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Addendum-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 14-Jul-2012 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 TPS53211RGTR QFN RGT 16 3000 330.0 12.4 3.3 3.3 1.1 8.0 12.0 Q2 TPS53211RGTT QFN RGT 16 250 180.0 12.4 3.3 3.3 1.1 8.0 12.0 Q2 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 14-Jul-2012 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) TPS53211RGTR QFN RGT 16 3000 367.0 367.0 35.0 TPS53211RGTT QFN RGT 16 250 210.0 185.0 35.0 Pack Materials-Page 2 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46C and to discontinue any product or service per JESD48B. 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