TPS61097 www.ti.com .............................................................................................................................................................. SLVS872A – JUNE 2009 – REVISED JULY 2009 LOW INPUT VOLTAGE SYNCHRONOUS BOOST CONVERTER WITH LOW QUIESCENT CURRENT FEATURES 1 • • • • • • • Up to 95% Efficiency at Typical Operating Conditions Connection from Battery to Load via Bypass Switch in Shutdown Mode Typical Shutdown Current Less Than 5 nA Typical Quiescent Current Less Than 5 µA Operating Input Voltage Range From 0.9 V to 5.5 V Fixed Output Voltage Options From 1.8 V to 5.0 V Power-Save Mode for Improved Efficiency at Low Output Power • • Overtemperature Protection Small 2.8-mm x 2.9-mm 5-Pin SOT-23 Package APPLICATIONS • • • • • • • MSP430 Applications All Single-Cell, Two-Cell, and Three-Cell Alkaline, NiCd, NiMH, or Single-Cell Li-Battery Powered Products Personal Medical Products Fuel Cell and Solar Cell Powered Products PDAs Mobile Applications White LEDs DESCRIPTION The TPS61097 provide a power supply solution for products powered by either a single-cell, two-cell, or three-cell alkaline, NiCd, or NiMH, or one-cell Li-Ion or Li-polymer battery. They can also be used in fuel cell or solar cell powered devices where the capability of handling low input voltages is essential. Possible output currents depend on the input-to-output voltage ratio. The devices provides output currents up to 100 mA at a 3.3-V output while using a single-cell Li-Ion or Li-Polymer battery. The boost converter is based on a current-mode controller using synchronous rectification to obtain maximum efficiency. The maximum average input current is limited to a value of 350 mA. The output voltage can be programmed by an external resistor divider, or it is fixed internally on the chip. The converter can be disabled to minimize battery drain. During shutdown, the battery is connected to the load to enable battery backup of critical functions on the load. The device is packaged in a 5-pin SOT-23 package (DBV) measuring 2.8 mm × 2.9 mm. TPS61097-33 L VOUT 3.3 V VOUT L1 C2 VIN 0.9 V to 3.3 V VIN C1 EN GND 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 © 2009, Texas Instruments Incorporated TPS61097 SLVS872A – JUNE 2009 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com AVAILABLE DEVICE OPTIONS (1) (2) TA OUTPUT VOLTAGE DC/DC Adjustable 1.8 V –40°C to 85°C Reel of 1000 TPS61097-ADJDRSR PREVIEW 6-pin SON – DRS Reel of 1000 TPS61097-18DRSR PREVIEW Reel of 3000 TPS61097-18DBVR Reel of 250 TPS61097-18DBVT Reel of 1000 TPS61097-27DRSR Reel of 3000 TPS61097-27DBVR Reel of 250 TPS61097-27DBVT Reel of 1000 TPS61097-30DRSR Reel of 3000 TPS61097-30DBVR Reel of 250 TPS61097-30DBVT Reel of 1000 TPS61097-33DRSR Reel of 3000 TPS61097-33DBVR Reel of 250 TPS61097-33DBVT Reel of 1000 TPS61097-50DRSR Reel of 3000 TPS61097-50DBVR Reel of 250 TPS61097-50DBVT 5-pin SOT-23 – DBV 5-pin SOT-23 – DBV 6-pin SON – DRS 3.0 V 5-pin SOT-23 – DBV 6-pin SON – DRS 3.3 V 5-pin SOT-23 – DBV 6-pin SON – DRS 5.0 V (1) (2) (3) 2 TOP-SIDE MARKING 6-pin SON – DRS 6-pin SON – DRS 2.7 V ORDERABLE PART NUMBER PACKAGE (3) 5-pin SOT-23 – DBV PREVIEW PREVIEW PREVIEW PREVIEW PREVIEW PREVIEW YC4L PREVIEW PREVIEW For the most current package and ordering information, see the Package Option Addendum at the end of this document, or see the TI web site at www.ti.com. Contact the factory for availability of other fixed output voltage versions. Package drawings, thermal data, and symbolization are available at www.ti.com/packaging. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated TPS61097 www.ti.com .............................................................................................................................................................. SLVS872A – JUNE 2009 – REVISED JULY 2009 ABSOLUTE MAXIMUM RATINGS over operating free-air temperature range (unless otherwise noted) (1) VI Input voltage range Isc Short-circuit current TJ Junction temperature range Tstg Storage temperature range ESD Electrostatic discharge rating (1) (2) VIN, L, VOUT, EN, FB –0.3 V to 7 V 400 mA –40°C to 150°C –65°C to 150°C Human-Body Model (HBM) (2) 2000 V 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. ESD testing is performed according to the respective JESD22 JEDEC standard. DISSIPATION RATINGS TABLE PACKAGE THERMAL RESISTANCE θJA POWER RATING TA ≤ 25°C DERATING FACTOR ABOVE TA = 25°C DRS TBD°C/W TBD mW TBD mW/°C DBV 255°C/W 390 mW -3.92 mW/°C RECOMMENDED OPERATING CONDITIONS MIN MAX 0.9 5.5 Adjustable output voltage 1.8 5.5 V Operating free air temperature range –40 85 °C Operating junction temperature range –40 125 °C VIN Supply voltage at VIN VOUT TA TJ Copyright © 2009, Texas Instruments Incorporated Submit Documentation Feedback UNIT V 3 TPS61097 SLVS872A – JUNE 2009 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com ELECTRICAL CHARACTERISTICS over recommended free-air temperature range and over recommended input voltage range (typical at an ambient temperature range of 25°C) (unless otherwise noted) DC/DC STAGE PARAMETER TEST CONDITIONS MIN VIN Input voltage VOUT TPS61097-ADJ output voltage range VFB TPS61097-ADJ feedback voltage VIN = 1.2 V , IOUT = 10 mA 1.16 TPS61097-18 VIN = 1.2 V , IOUT = 10 mA 1.75 TPS61097-27 VIN = 1.2 V , IOUT = 10 mA TPS61097-30 VIN = 1.2 V , IOUT = 10 mA TPS61097-33 VOUT ISW TYP MAX UNIT 0.9 5.5 V 1.8 5.0 V 1.20 1.24 V 1.80 1.85 2.62 2.70 2.78 2.91 3.00 3.09 VIN = 1.2 V , IOUT = 10 mA 3.20 3.30 3.40 TPS61097-50 VIN = 2.4 V , IOUT = 10 mA 4.85 5.00 5.15 Switch current limit VOUT = 3.3 V 200 350 475 Rectifying switch on resistance VOUT = 3.3 V 1.0 Ω Main switch on resistance VOUT = 3.3 V 1.0 Ω Bypass switch on resistance VIN = 1.2 IOUT = 100 mA 3.4 Ω Line regulation VIN < VOUT, VIN = 1.2 V to 1.8 V, IOUT = 10 mA 0.5% Load regulation VIN < VOUT, IOUT = 10 mA to 50 mA, VIN = 1.8 V 0.5% IQ Quiescent current ISD Shutdown current VIN VOUT VIN Leakage current into L VIN < VOUT IO = 0 mA, VEN = VIN = 1.2 V, VOUT = 3.4V VEN = 0 V, VIN = 1.2 V, IOUT = 0 mA VEN = 0 V, VIN = 1.2 V, VL = 1.2 V V mA 1 2.5 µA 4 6.5 µA 0.005 0.15 µA 0.01 1 µA TYP MAX 0.01 0.1 µA 0.65 V CONTROL STAGE PARAMETER EN input current VIL Logic low level, EN falling edge VIH Logic high level, EN rising edge Overvoltage protection threshold VUVLO 4 TEST CONDITIONS MIN EN = 0 V or EN = VIN 0.78 TPS61097-ADJ 5.5 UNIT V 6.5 7 V Overtemperature protection 150 °C Overtemperature hysteresis 20 °C Undervoltage lock-out threshold for turn off Submit Documentation Feedback VIN decreasing 0.5 0.7 Copyright © 2009, Texas Instruments Incorporated TPS61097 www.ti.com .............................................................................................................................................................. SLVS872A – JUNE 2009 – REVISED JULY 2009 PIN ASSIGNMENTS 4 VOUT 6 GND 2 EN 3 L 5 NC 4 VOUT VIN 1 GND 2 EN 6 W 3 1 IE EN VIN EV 2 L ADJUSTABLE OUTPUT VOLAGE DRS PACKAGE (TOP VIEW) PR GND 5 IE W 1 EV VIN FIXED OUTPUT VOLTAGE DRS PACKAGE (TOP VIEW) PR FIXED OUTPUT VOLTAGE DBV PACKAGE (TOP VIEW) 3 L 5 FB 4 VOUT NC – No internal connection Terminal Functions TERMINAL NAME NO. I/O DESCRIPTION DBV DRS VIN 1 1 GND 2 2 EN 3 3 I Enable input (1 = enabled, 0 = disabled). EN must be actively terminated high or low. VOUT 4 4 O Boost converter output L 5 6 I Connection for inductor FB – 5 I (Adjustable versions) Voltage feedback of adjustable versions. Exposed Thermal Pad I Boost converter input voltage Control / logic ground – Copyright © 2009, Texas Instruments Incorporated Must be soldered to PCB to achieve appropriate power dissipation. Should be connected to GND. Submit Documentation Feedback 5 TPS61097 SLVS872A – JUNE 2009 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com FUNCTIONAL BLOCK DIAGRAM (FIXED OUTPUT VERSION) Bypass Switch P N L VOUT Rectifying Switch Thermal Shutdown Startup Circuit N Driver VIN Undervoltage Lockout Bypass Switch Control Main Switch Control Logic Current Sense EN Overvoltage Protection GND 1.20 V 6 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated TPS61097 www.ti.com .............................................................................................................................................................. SLVS872A – JUNE 2009 – REVISED JULY 2009 FUNCTIONAL BLOCK DIAGRAM (ADJUSTABLE OUTPUT VERSION) Bypass Switch P N L VOUT Rectifying Switch Thermal Shutdown Startup Circuit N Driver VIN Undervoltage Lockout Bypass Switch Control Main Switch Control Logic Current Sense EN Overvoltage Protection FB GND 1.20 V Copyright © 2009, Texas Instruments Incorporated Submit Documentation Feedback 7 TPS61097 SLVS872A – JUNE 2009 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com PARAMETER MEASUREMENT INFORMATION TPS61097-33 L VOUT 3.3 V VOUT L1 C2 VIN 0.9 V to 3 V VIN C1 EN GND C1 10 µF C2 10 µF L 10 µH Table 1. List of Components 8 REFERENCE MANUFACTURER PART NO. C1 Murata GRM319R61A106KE19 10µF 10V X5R 1206 20% C2 Murata GRM319R61A106KE19 10µF 10V X5R 1206 20% L1 Coilcraft DO3314-103MLC Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated TPS61097 www.ti.com .............................................................................................................................................................. SLVS872A – JUNE 2009 – REVISED JULY 2009 TYPICAL CHARACTERISTICS Table 2. Table of Graphs FIGURE Maximum Output Current Efficiency Input Current Startup Voltage Output Voltage Waveforms vs Input Voltage 1 vs Output Current 2 vs Input Voltage 3 vs Input Voltage (Device Enabled, No Output Load, VOUT = 3.3 V) 4 vs Input Voltage (Device Disabled, No Output Load) 5 vs Temperature 6 vs Output Current 7 vs Output Current 8 vs Input Voltage 9 Output Voltage Ripple 10 Load Transient Response 11 Line Transient Response 12 Switching Waveform, Continuous Mode 13 Switching Waveform, Discontinuous Mode 14 Startup After Enable (VIN = 1.2 V, IOUT = 10 mA) 15 Startup After Enable (VIN = 1.8 V, IOUT = 10 mA) 16 MAXIMUM OUTPUT CURRENT vs INPUT VOLTAGE EFFICIENCY vs OUTPUT CURRENT 0.25 100 90 0.20 80 70 Efficiency – % IO(max) – Maximum Output Current – A COUT = 10 µF, ceramic L = 10 µH 0.15 0.10 VIN = 3 V 60 VIN = 2.5 V 50 VIN = 1.8 V 40 VIN = 1.5 V 30 0.05 VIN = 1.2 V 20 COUT = 10 µF, ceramic L = 10 µH 10 0.00 VIN = 0.9 V 0 0.9 1.2 1.5 1.8 2.1 2.4 VI – Input Voltage – V Figure 1. Copyright © 2009, Texas Instruments Incorporated 2.7 3 0.1 1 10 100 IO – Output Current – mA Figure 2. Submit Documentation Feedback 9 TPS61097 SLVS872A – JUNE 2009 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com EFFICIENCY vs INPUT VOLTAGE INPUT CURRENT vs INPUT VOLTAGE 100 20 IOUT = 10 mA 90 18 80 16 IIN – Input Current – µA Efficiency – % 70 IOUT = 100 µA 60 IOUT = 5 mA IOUT = 100 mA 50 IOUT = 50 mA 40 30 20 12 10 8 6 2 0 0 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3.0 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3 VIN – Input Voltage – V VIN – Input Voltage – V Figure 3. Figure 4. INPUT CURRENT vs INPUT VOLTAGE STARTUP VOLTAGE vs TEMPERATURE 120 3.3 3.6 3.9 4.2 0.720 VIN = 1.8 V No Load Device Disabled No Output Load 0.718 100 0.716 80 Startup Voltage – V IIN – Input Current – nA 14 4 COUT = 10 µF, ceramic L = 10 µH 10 60 40 0.714 0.712 0.710 20 0.708 0 0.9 1.2 1.5 1.8 2.1 2.4 2.7 3 3.3 3.6 3.9 4.2 VIN – Input Voltage – V Figure 5. 10 Device Enabled No Output Load VOUT = 3.3 V Submit Documentation Feedback 0.706 -40 -25 -10 5 20 35 50 65 80 TA – Temperature – °C Figure 6. Copyright © 2009, Texas Instruments Incorporated TPS61097 www.ti.com .............................................................................................................................................................. SLVS872A – JUNE 2009 – REVISED JULY 2009 STARTUP VOLTAGE vs OUTPUT CURRENT OUTPUT VOLTAGE vs OUTPUT CURRENT 0.725 3.32 COUT = 10 µF, ceramic L = 10 µH VIN = 1.8 V 3.30 VOUT – Output Voltage – V Startup Voltage – V 0.720 0.715 0.710 0.705 VIN = 2.1 V VIN = 2.5 V VIN = 2.7 V VIN = 3.0 V 3.28 VIN = 0.9 V VIN = 1.2 V 3.26 VIN = 1.5 V VIN = 1.8 V 3.24 3.22 3.20 0.700 0 1 10 1 100 10 100 IOUT – Output Current – mA 1000 IOUT – Output Current – mA Figure 7. Figure 8. OUTPUT VOLTAGE vs INPUT VOLTAGE 6 Device disabled VOUT – Ouput Voltage – V 5 4 RLOAD = 1k 3 RLOAD = 122 2 1 0 0 1 2 3 4 5 6 VIN – Input Voltage – V Figure 9. Copyright © 2009, Texas Instruments Incorporated Submit Documentation Feedback 11 TPS61097 SLVS872A – JUNE 2009 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com OUTPUT VOLTAGE RIPPLE Inductor Current VIN = 1.8 V IOUT = 50 mA COUT = 10 µF, ceramic L = 10 µH VOUT Figure 10. LOAD TRANSIENT RESPONSE IOUT VIN = 1.2 V IOUT = 6 mA to 50 mA VOUT Figure 11. 12 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated TPS61097 www.ti.com .............................................................................................................................................................. SLVS872A – JUNE 2009 – REVISED JULY 2009 LINE TRANSIENT RESPONSE VIN Offset 1.8 V VIN = 1.8 V to 2.4 V RLOAD = 100 W VOUT Figure 12. SWITCHING WAVEFORM, CONTINUOUS MODE VIN = 1.8 V IOUT = 50 mA Inductor Current Inductor Voltage VOUT Figure 13. Copyright © 2009, Texas Instruments Incorporated Submit Documentation Feedback 13 TPS61097 SLVS872A – JUNE 2009 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com SWITCHING WAVEFORM, DISCONTINUOUS MODE VIN = 1.8 V IOUT = 10 mA Inductor Current Inductor Voltage VOUT Figure 14. STARTUP AFTER ENABLE VIN = 1.2 V IOUT = 10 mA VOUT VEN Figure 15. 14 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated TPS61097 www.ti.com .............................................................................................................................................................. SLVS872A – JUNE 2009 – REVISED JULY 2009 STARTUP AFTER ENABLE VIN = 1.8 V IOUT = 10 mA VOUT VEN Figure 16. Copyright © 2009, Texas Instruments Incorporated Submit Documentation Feedback 15 TPS61097 SLVS872A – JUNE 2009 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com DETAILED DESCRIPTION Operation The TPS61097 is a high performance, high efficient family of switching boost converters. To achieve high efficiency the power stage is realized as a synchronous boost topology. For the power switching two actively controlled low RDSon power MOSFETs are implemented. Controller Circuit The device is controlled by a hysteretic current mode controller. This controller regulates the output voltage by keeping the inductor ripple current constant in the range of 200 mA and adjusting the offset of this inductor current depending on the output load. If the required average input current is lower than the average inductor current defined by this constant ripple the inductor current goes discontinuous to keep the efficiency high at low load conditions. IL Continuous Current Operation Discontinuous Current Operation 200 mA (typ.) 200 mA (typ.) t Figure 17. Hysteretic Current Operation The output voltage VOUT is monitored via the feedback network which is connected to the voltage error amplifier. To regulate the output voltage, the voltage error amplifier compares this feedback voltage to the internal voltage reference and adjusts the required offset of the inductor current accordingly. For fixed output voltage versions, the feedback function is connected internally. A resistive divider network is required to set the output voltage with the adjustable option. The self oscillating hysteretic current mode architecture is inherently stable and allows fast response to load variations. It also allows using inductors and capacitors over a wide value range. Device Enable and Shutdown Mode The device is enabled when EN is set high and shut down when EN is low. During shutdown, the converter stops switching and all internal control circuitry is turned off. Bypass Switch The TPS61097 contains a P-channel MOSFET (Bypass Switch) in parallel with the synchronous rectifying MOSFET. When the IC is enabled (EN = VIH), the Bypass Switch is turned off to allow the IC to work as a standard boost converter. When the IC is disabled (EN = VIL) the Bypass Switch is turned on to provide a direct, low impedance connection from the input voltage (at the L pin) to the load (VOUT). The Bypass Switch is not impacted by Undervoltage lockout, Overvoltage or Thermal shutdown. Startup After the EN pin is tied high, the device starts to operate. If the input voltage is not high enough to supply the control circuit properly a startup oscillator starts to operate the switches. During this phase the switching frequency is controlled by the oscillator and the maximum switch current is limited. As soon as the device has built up the output voltage to about 1.8 V, high enough for supplying the control circuit, the device switches to its normal hysteretic current mode operation. The startup time depends on input voltage and load current. Operation at Output Overload If in normal boost operation the inductor current reaches the internal switch current limit threshold the main switch is turned off to stop further increase of the input current. In this case the output voltage will decrease since the device can not provide sufficient power to maintain the set output voltage. 16 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated TPS61097 www.ti.com .............................................................................................................................................................. SLVS872A – JUNE 2009 – REVISED JULY 2009 If the output voltage drops below the input voltage the backgate diode of the rectifying switch gets forward biased and current starts flow through it. Because this diode cannot be turned off, the load current is only limited by the remaining DC resistances. As soon as the overload condition is removed, the converter automatically resumes normal operation and enters the appropriate soft start mode depending on the operating conditions. Undervoltage Lockout An undervoltage lockout function stops the operation of the converter if the input voltage drops below the typical undervoltage lockout threshold. This function is implemented in order to prevent malfunctioning of the converter. The undervoltage lockout function has no control of the Bypass Switch. If the Bypass Switch is enabled (EN = VIL) there is no impact during an undervoltage condition, the Bypass Switch remains on. Overvoltage Protection If, for any reason, TPS61097-ADJ output voltage is not properly connected to the input of the voltage amplifier, the IC cannot control the output voltage. Therefore an overvoltage protection is implemented to keep the output voltage from exceeding the absolute maximum voltage ratings of the IC and to protect the load. For this protection the TPS61097-ADJ output voltage is also monitored internally. In case it reaches the internally programmed threshold of 6.5 V typically the voltage amplifier regulates the output voltage to this value. If the TPS61097-ADJ is used to drive LEDs, this feature protects the circuit if the LED fails. Overtemperature Protection The device has a built-in temperature sensor which monitors the internal IC temperature. If the temperature exceeds the programmed threshold (150 °C typical), the device stops operating. As soon as the IC temperature has decreased below the programmed threshold, it starts operating again. There is a built-in hysteresis to avoid unstable operation at IC temperatures at the overtemperature threshold. Copyright © 2009, Texas Instruments Incorporated Submit Documentation Feedback 17 TPS61097 SLVS872A – JUNE 2009 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com APPLICATION INFORMATION Design Procedure The TPS61097 DC/DC converters are intended for systems powered by a single up to triple cell Alkaline, NiCd, NiMH battery with a typical terminal voltage between 0.9 V and 5.5 V. They can also be used in systems powered by one-cell Li-Ion or Li-Polymer with a typical voltage between 2.5 V and 4.2 V. Additionally, any other voltage source like solar cells or fuel cells with a typical output voltage between 0.9 V and 5.5 V can power systems where the TPS61097 is used. The TPS61097 does not down-regulate VIN; therefore, if VIN is greater than VOUT, VOUT tracks VIN. Programming the Output Voltage Within the TPS61097 family, there are fixed and adjustable output voltage versions available. For the adjustable output voltage versions, an external resistor divider is used to adjust the output voltage. The resistor divider must be connected between VOUT, FB, and GND. When the output voltage is regulated properly, the typical value of the voltage at the FB pin is 1.2 V. The maximum recommended value for the output voltage is 5.5 V. The current through the resistive divider should be about 100 times greater than the current into the FB pin. The typical current into the FB pin is 0.01 µA, and the voltage across the resistor between FB and GND, R2, is typically 1.2 V. Based on those two values, the recommended value for R2 should be lower than 500 kΩ, in order to set the divider current at 1 µA or higher. It is recommended to keep the value for this resistor in the range of 100 kΩ. Equation 1 calculates the value of R1 to set the desired output voltage: R3 = R4 × VOUT –1 VFB (1) As an example, if an output voltage of 2.5 V is needed, a 162-kΩ resistor should be chosen for R1 when a 150-kΩ has been selected for R2. TPS61097-ADJ L VOUT 1.8 V to 5.5 V VOUT L1 R1 VIN 0.9 V to VOUT VIN C2 FB R2 C1 EN GND Figure 18. Typical Application Circuit for Adjustable Output Voltage Option Adjustable Bypass Switching The EN pin can be set up as a low voltage control for the bypass switch. By setting the desired ratio of R1 and R2, the TPS61097 can be set to switch on the bypass at a defined voltage level on VIN. For example, setting R1 and R2 to 200K Ω would set VEN to half of VIN. The voltage level of VIN engaging the bypass switch is based on the VIL level of EN (0.65 V). If VIN is less than 1.30 V then the bypass switch will be enabled. For VIN values above 1.50 V (50% of VIH) the bypass switch is disabled. 18 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated TPS61097 www.ti.com .............................................................................................................................................................. SLVS872A – JUNE 2009 – REVISED JULY 2009 TPS61097-33 L VOUT 3.3 V VOUT L1 C2 VIN 0.9 V to V VIN R1 C1 EN R2 GND Figure 19. Adjustable Bypass Switching Inductor Selection To make sure that the TPS61097 devices can operate, a suitable inductor must be connected between pin VIN and pin L. Inductor values of 4.7 µH show good performance over the whole input and output voltage range . Choosing other inductance values affects the switching frequency f proportional to 1/L as shown in Equation 2. L= V ´ (VOUT - VIN ) 1 ´ IN f ´ 200 mA VOUT (2) Choosing inductor values higher than 4.7 µH can improve efficiency due to reduced switching frequency and therefore with reduced switching losses. Using inductor values below 2.2 µH is not recommended. Having selected an inductance value, the peak current for the inductor in steady state operation can be calculated. Equation 3 gives the peak current estimate. IL,MAX ì VOUT ´ IOUT + 100 mA; continous current operation ï = í 0.8 ´ VIN ï200 mA; discontinuous current operation î (3) IL,MAX is the inductor's required minimum current rating. Note that load transient or over current conditions may require an even higher current rating. Equation 4 provides an easy way to estimate whether the device is operating in continuous or discontinuous operation. As long as the equation is true, continuous operation is typically established. If the equation becomes false, discontinuous operation is typically established. VOUT ´ IOUT > 0.8 ´ 100 mA VIN (4) Due to the use of current hysteretic control in the TPS61097, the series resistance of the inductor can impact the operation of the main switch. There is a simple calculation that can ensure proper operation of the TPS61097 boost converter. The relationship between the series resistance (RIN), the input voltage (VIN) and the switch current limit (ISW) is shown in Equation 5. RIN < VIN / ISW (5) Examples: ISW = 400 mA, VIN = 2.5 V (6) In Equation 6, RIN < 2.5 V / 400 mA; therefore, RIN must be less than 6.25 Ω. Copyright © 2009, Texas Instruments Incorporated Submit Documentation Feedback 19 TPS61097 SLVS872A – JUNE 2009 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com ISW = 400 mA, VIN = 1.8 V (7) In Equation 7, RIN < 1.8 V / 400 mA; therefore, RIN must be less than 4.5 Ω. The following inductor series from different suppliers have been used with TPS61097 converters: Table 3. List of Inductors VENDOR INDUCTOR SERIES Coilcraft DO3314 TDK NLC565050T Taiyo Yuden CBC2012T Capacitor Selection Input Capacitor The input capacitor should be at least 10-µF to improve transient behavior of the regulator and EMI behavior of the total power supply circuit. The input capacitor should be a ceramic capacitor and be placed as close as possible to the VIN and GND pins of the IC. Output Capacitor For the output capacitor C2, it is recommended to use small ceramic capacitors placed as close as possible to the VOUT and GND pins of the IC. If, for any reason, the application requires the use of large capacitors which can not be placed close to the IC, the use of a small ceramic capacitor with an capacitance value of around 2.2µF in parallel to the large one is recommended. This small capacitor should be placed as close as possible to the VOUT and GND pins of the IC. A minimum capacitance value of 4.7 µF should be used, 10 µF are recommended. If the inductor value exceeds 4.7 µH, the value of the output capacitance value needs to be half the inductance value or higher for stability reasons, see Equation 8. C2 ³ L ´ 2 (8) The TPS61097 is not sensitive to the ESR in terms of stability. Using low ESR capacitors, such as ceramic capacitors, is recommended to minimize output voltage ripple. If heavy load changes are expected, the output capacitor value should be increased to avoid output voltage drops during fast load transients. Table 4. Recommended Output Capacitors 20 VENDOR CAPACITOR SERIES Murata GRM188R60J106M47D 10µF 6.3V X5R 0603 Murata GRM319R61A106KE19 10µF 10V X5R 1206 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated TPS61097 www.ti.com .............................................................................................................................................................. SLVS872A – JUNE 2009 – REVISED JULY 2009 Layout Considerations As for all switching power supplies, the layout is an important step in the design, especially at high peak currents and high switching frequencies. If the layout is not carefully done, the regulator could show stability problems as well as EMI problems. Therefore, use wide and short traces for the main current path and for the power ground tracks. The input and output capacitor, as well as the inductor should be placed as close as possible to the IC. Use a common ground node for power ground and a different one for control ground to minimize the effects of ground noise. Connect these ground nodes at any place close to one of the ground pins of the IC. The feedback divider should be placed as close as possible to the control ground pin of the IC. To lay out the control ground, it is recommended to use short traces as well, separated from the power ground traces. This avoids ground shift problems, which can occur due to superimposition of power ground current and control ground current. Figure 20. Layout Schematic Copyright © 2009, Texas Instruments Incorporated Submit Documentation Feedback 21 TPS61097 SLVS872A – JUNE 2009 – REVISED JULY 2009 .............................................................................................................................................................. www.ti.com Figure 21. PCB Top View Thermal Information Implementation of integrated circuits in low-profile and fine-pitch surface-mount packages typically requires special attention to power dissipation. Many system-dependent issues such as thermal coupling, airflow, added heat sinks and convection surfaces, and the presence of other heat-generating components affect the power-dissipation limits of a given component. Three basic approaches for enhancing thermal performance are listed below. • Improving the power dissipation capability of the PCB design • Improving the thermal coupling of the component to the PCB • Introducing airflow in the system The maximum recommended junction temperature (TJ) of the TPS61097 devices is 125°C. The thermal resistance of the 6-pin SON 3 × 3 package (DRS) is RθJA = TBD °C/W, if the thermal pad is soldered. Specified regulator operation is assured to a maximum ambient temperature TA of 85°C. Therefore, the maximum power dissipation is about TBD mW. More power can be dissipated if the maximum ambient temperature of the application is lower. 22 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated PACKAGE OPTION ADDENDUM www.ti.com 2-Jul-2009 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Eco Plan (2) Qty TPS61097-33DBVR ACTIVE SOT-23 DBV 5 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS61097-33DBVT ACTIVE SOT-23 DBV 5 250 CU NIPDAU Level-1-260C-UNLIM Green (RoHS & no Sb/Br) Lead/Ball Finish MSL Peak Temp (3) (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 1-Jul-2009 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel Diameter Width (mm) W1 (mm) TPS61097-33DBVR SOT-23 DBV 5 3000 180.0 TPS61097-33DBVT SOT-23 DBV 5 250 180.0 A0 (mm) B0 (mm) K0 (mm) P1 (mm) 9.2 3.23 3.17 1.37 4.0 8.0 Q3 9.2 3.23 3.17 1.37 4.0 8.0 Q3 Pack Materials-Page 1 W Pin1 (mm) Quadrant PACKAGE MATERIALS INFORMATION www.ti.com 1-Jul-2009 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) TPS61097-33DBVR SOT-23 DBV 5 3000 205.0 200.0 33.0 TPS61097-33DBVT SOT-23 DBV 5 250 205.0 200.0 33.0 Pack Materials-Page 2 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. 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