TPS61093 www.ti.com.......................................................................................................................................................................................... SLVS992 – SEPTEMBER 2009 LOW INPUT BOOST CONVERTER WITH INTEGRATED POWER DIODE AND INPUT/OUTPUT ISOLATION FEATURES 1 • • • • • • • • • DESCRIPTION Input Range: 1.6-V to 6-V Integrated Power Diode and Isolation FET 20-V Internal Switch FET With 1.1-A Current Fixed 1.2-MHz Switching Frequency Efficiency at 15-V Output up to 88% Over Load and Over Voltage Protection Programmable Soft Start-up Load Discharge Path After IC Shutdown 2.5 × 2.5 × 0.8 mm SON Package The TPS61093 is a 1.2-MHz, fixed-frequency boost converter designed for high integration and high reliability. The IC integrates a 20-V power switch, input/output isolation switch, and power diode. When the output current exceeds the over load limit, the IC’s isolation switch opens up to disconnect the output from the input. This protects the IC and the input supply. The isolation switch also disconnects the output from the input during shutdown to minimize leakage current. When the IC is shutdown, the output capacitor is discharged to a low voltage level by internal diodes. Other protection features include 1.1-A peak over-current protection (OCP) at each cycle, output over voltage protection (OVP), thermal shutdown, and under voltage lockout (UVLO). APPLICATIONS • • • Glucose Meter OLED Power Supply 3.3-V to 12-V, 5-V to 12-V Boost Converter With its 1.6-V minimum input voltage, the IC can be powered by two alkaline batteries, a single Li-ion battery, or 3.3-V and 5-V regulated supply. The output can be boosted up to 17-V. The TPS61093 is available in 2.5 mm × 2.5 mm SON package with thermal pad. VI 1.6 V to 6 V L1 10 mH C1 4.7 mF C3 TPS61093 VIN SW CP1 VO CP2 OUT 100 nF R3 200 kW EN FB SS GND C2 0.1 mF C5 1 mF VO 15 V/50 mA R1 294 kW C4 1 mF R2 10.2 kW Figure 1. Typical Application ORDERING INFORMATION (1) (1) (2) TA PART NUMBER (2) PACKAGE MARKING –40°C to 85°C TPS61093DSK OAP 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 The DSK package is available in tape and reel. Add R suffix (TPS61093DSKR) to order quantities of 3000 parts per reel, or add T suffix (TPS61093DSKT) to order 250 parts per reel. 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 TPS61093 SLVS992 – SEPTEMBER 2009.......................................................................................................................................................................................... www.ti.com ABSOLUTE MAXIMUM RATINGS over operating free-air temperature range (unless otherwise noted) (1) VALUE / UNITS Supply voltage on pin VIN (2) –0.3 V to 7 V Voltage on pins CP2, EN, and SS (2) –0.3 V to 7 V Voltage on pin CP1 and FB (2) –0.3 V to 3 V Voltage on pin SW, VO, and OUT (2) HBM ESD Rating –0.3 V to 20 V (3) 2 kV Operating temperature range, TA –40°C to 85°C Maximum operating junction temperature, TJ 150°C Storage temperature, Tst (1) (2) (3) –55°C to 150°C 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 network ground terminal. The Human body model (HBM) is a 100-pF capacitor discharged through a 1.5-kΩ resistor into each pin. The testing is done according JEDECs EIA/JESD22-A114. DISSIPATION RATINGS (1) PACKAGE THERMAL RESISTANCE θJA (1) THERMAL RESISTANCE θJP THERMAL RESISTANCE θJC POWER RATING TA ≤ 25°C (1) DERATING FACTOR ABOVE TA = 25°C (1) DSK 60.6°C/W 6.3°C/W 40°C/W 1650 mW 17 mW/°C Thermal ratings are determined assuming a high K PCB design according to JEDEC standard JESD51-7. RECOMMENDED OPERATING CONDITIONS over operating free-air temperature range (unless otherwise noted) MIN Vi Input voltage range Vo Output voltage range at VO pin L Inductor (1) Cin Input capacitor NOM 1.6 2.2 MAX 6 4.7 V 10 µH µF Output capacitor at OUT pin Cfly Flying capacitor at CP1 and CP2 pins TJ Operating junction temperature –40 125 °C TA Operating free-air temperature –40 85 °C 2 10 µF Co (1) 1 V 17 4.7 (1) UNIT 10 nF These values are recommended values that have been successfully tested in several applications. Other values may be acceptable in other applications but should be fully tested by the user. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS61093 TPS61093 www.ti.com.......................................................................................................................................................................................... SLVS992 – SEPTEMBER 2009 ELECTRICAL CHARACTERISTICS VIN = 3.6 V, EN = VIN, TA = –40°C to 85°C, typical values are at TA = 25°C (unless otherwise noted) PARAMETER TEST CONDITIONS MIN TYP MAX UNIT SUPPLY CURRENT VIN Input voltage range, VIN 1.6 IQ Operating quiescent current into VIN Device PWM switching no load ISD Shutdown current EN = GND, VIN = 6 V UVLO Undervoltage lockout threshold VIN falling Vhys Undervoltage lockout hysterisis 6 0.9 1.5 V 1.5 mA 1 µA 1.55 V 50 mV ENABLE AND PWM CONTROL VENH EN logic high voltage VIN = 1.6 V to 6 V VENL EN logic low voltage VIN = 1.6 V to 6 V REN EN pull down resistor Toff EN pulse width to shutdown 1.2 V 0.3 400 800 EN high to low V 1600 kΩ 1 ms VOLTAGE CONTROL VREF Voltage feedback regulation voltage IFB Voltage feedback input bias current fS Oscillator frequency Dmax Maximum duty cycle Tmin_on Minimum on pulse width 0.49 VFB = 0.1 V, TA = 85°C 0.5 1.0 1.2 90% 93% 0.51 V 100 nA 1.4 MHz 65 ns POWER SWITCH, ISOLATION FET RDS(ON)N N-channel MOSFET on-resistance VIN = 3 V 0.25 0.4 Ω RDS(ON)iso Isolation FET on-resistance VO = 5 V 2.5 4 Ω VO = 3.5 V 4.5 1 µA 1 µA ILN_N N-channel leakage current VDS = 20 V, TA = 25°C ILN_iso Isolation FET leakage current VDS = 20 V, TA = 25°C VF Power diode forward voltage Current = 500 mA 0.8 V OC, ILIM, OVP SC AND SS ILIM N-Channel MOSFET current limit Vovp Over voltage protection threshold Vovp_hys Over voltage protection hysteresis IOL Over load protection Measured on the VO pin 0.9 1.1 18 19 V 0.6 V 300 mA 200 1.5 A THERMAL SHUTDOWN Tshutdown Thermal shutdown threshold 150 °C Thysteresis Thermal shutdown hysteresis 15 °C Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS61093 3 TPS61093 SLVS992 – SEPTEMBER 2009.......................................................................................................................................................................................... www.ti.com DEVICE INFORMATION PIN ASSIGNMENTS TOP VIEW GND 1 10 VIN VO SW Thermal Pad CP2 OUT CP1 FB EN 5 6 SS 10-PIN 2.5mm x 2.5mm QFN PIN FUNCTIONS PIN NAME NO. I/O DESCRIPTION VIN 2 I IC Supply voltage input. VO 10 O Output of the boost converter. When the output voltage exceeds the over voltage protection (OVP) threshold, the power switch turns off until VO drops below the over voltage protection hysteresis. OUT 8 O Isolation switch is between this pin and VO pin. Connect load to this pin for input/output isolation during IC shutdown. See WITHOUT ISOLATION FET for the tradeoff between isolation and efficiency. 1 – Ground of the IC. GND CP1, CP2 3, 4 Connect to flying capacitor for internal charge pump. EN 5 I Enable pin (HIGH = enable). When the pin is pulled low for 1 ms, the IC turns off and consumes less than 1-µA current. SS 6 I Soft start pin. A RC network connecting to the SS pin programs soft start timing. See START UP. FB 7 I Voltage feedback pin for output regulation, 0.5-V regulated voltage. An external resistor divider connected to this pin programs the regulated output voltage. SW 9 I Switching node of the IC where the internal PWM switch operates. Thermal Pad – – It should be soldered to the ground plane. If possible, use thermal via to connect to ground plane for ideal power dissipation. 4 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS61093 TPS61093 www.ti.com.......................................................................................................................................................................................... SLVS992 – SEPTEMBER 2009 FUNCTIONAL BLOCK DIAGRAM FB EN CP2 CP1 SW OUT VO Soft Startup Ref. C/P EA Gate Driver PWM Control Gate Driver EN Precharge On/off control Oscillator Ramp Generator + Current Sensor SS GND VIN TYPICAL CHARACTERISTICS TABLE OF GRAPHS Figure 1, L = TOKO #A915_Y-100M, unless otherwise noted FIGURE η Efficiency vs Load current at OUT = 15 V 2 η Efficiency vs Load current at OUT = 10 V 3 VFB FB voltage vs Free-air temperature 4 VFB FB voltage vs Input voltage 5 ILIM Switch current limit vs Free-air temperature 6 Line transient response VIN = 3.3 V to 3.6 V; Load = 50 mA 7 Load transient response VIN = 2.5 V; Load = 10 mA to 50 mA; Cff = 100 pF 8 PWM control in CCM VIN = 3.6 V; Load = 50 mA 9 PWM control in DCM VIN = 3.6 V; Load = 1 mA 10 Pulse skip mode VIN = 4.5 V; OUT = 10 V; No load 11 Soft start-up VIN = 3.6 V; Load = 50 mA 12 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS61093 5 TPS61093 SLVS992 – SEPTEMBER 2009.......................................................................................................................................................................................... www.ti.com EFFICIENCY vs LOAD EFFICIENCY vs LOAD 100 100 OUT = 15 V 95 85 85 80 80 75 VI = 2.5 V 70 VI =1.8 V 65 70 55 55 50 50 45 45 100 40 1 1000 VI = 2.5 V VI =1.8 V 65 60 10 VI = 3.3 V 75 60 40 1 VI = 4.2 V 90 VI = 3.3 V Efficiency - % Efficiency - % 90 OUT = 10 V 95 VI = 4.2 V 10 Load - mA Figure 2. 100 1000 Load - mA Figure 3. FB VOLTAGE vs FREE-AIR TEMPERATURE FB VOLTAGE vs INPUT VOLTAGE 0.502 502 501.5 0.501 VFB - mV VFB - V 501 0.5 500.5 500 0.499 499.5 0.498 -40 -20 0 20 40 60 80 TA - Free-Air Temperature - ºC 100 120 499 1.6 Figure 4. 6 2 2.4 2.8 3.2 3.6 4 4.4 4.8 5.2 5.6 VI - Input Voltage - V 6 Figure 5. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS61093 TPS61093 www.ti.com.......................................................................................................................................................................................... SLVS992 – SEPTEMBER 2009 SWITCH CURRENT LIMIT vs FREE-AIR TEMPERATURE 3.3V to 3.6V LINE TRANSIENT RESPONSE 1.3 OUT 500 mV/div; AC ILIM - A 1.2 1.1 Inductor Current 200 mA/div 1 0.9 0.8 -40 -20 0 20 40 60 80 TA - Free-Air Temperature - ºC 100 t - Time = 1 ms/div 120 Figure 6. Figure 7. 10mA to 50mA LOAD TRANSIENT RESPONSE PWM CONTROL IN CCM OUT with Cff 500 mV/div; AC OUT 100 mV/div; AC OUT without Cff 500 mV/div; AC SW 10 V/div Inductor Current 200 mA/div Load 20 mA/div t - Time = 1 ms/div t - Time = 400 ns/div Figure 8. Figure 9. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS61093 7 TPS61093 SLVS992 – SEPTEMBER 2009.......................................................................................................................................................................................... www.ti.com PWM CONTROL IN DCM PULSE SKIP MODE AT LIGHT LOAD OUT 50 mV/div; AC OUT 100 mV/div; AC SW 10 V/div SW 10 V/div Inductor Current 20 mA/div Inductor Current 100 mA/div t - Time = 1 ms/div t - Time = 200 ns/div Figure 10. Figure 11. SOFT START-UP VO 5 V/div Inductor Current 100 mA/div OUT 5 V/div t - Time = 40 ms/div Figure 12. DETAILED DESCRIPTION OPERATION The TPS61093 is a highly integrated boost regulator for up to 17-V output. In addition to the on-chip 1-A PWM switch and power diode, this IC also integrates an output-side isolation switch as shown in the functional block diagram. One common issue with conventional boost regulators is the conduction path from input to output even when the PWM switch is turned off. It creates three problems, which are inrush current during start-up, output leakage current during shutdown, and excessive over load current. In the TPS61093, the isolation switch turns off under shutdown-mode and over load conditions, thereby opening the current path. However, shorting the VO and OUT pins bypasses the isolation switch and enhances efficiency. The TPS61093 adopts current-mode control with constant pulse-width-modulation (PWM) frequency. The switching frequency is fixed at 1.2-MHz typical. PWM operation turns on the PWM switch at the beginning of each switching cycle. The input voltage is applied across the inductor and the inductor current ramps up. In this mode, the output capacitor is discharged by the load current. When the inductor current hits the threshold set by 8 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS61093 TPS61093 www.ti.com.......................................................................................................................................................................................... SLVS992 – SEPTEMBER 2009 the error amplifier output, the PWM switch is turned off, and the power diode is forward-biased. The inductor transfers its stored energy to replenish the output capacitor. This operation repeats in the next switching cycle. The error amplifier compares the FB-pin voltage with an internal reference, and its output determines the duty cycle of the PWM switching. This closed-loop system requires frequency compensation for stable operation. The device has a built-in compensation circuit that can accommodate a wide range of input and output voltages. To avoid the sub-harmonic oscillation intrinsic to current-mode control, the IC also integrates slope compensation, which adds an artificial slope to the current ramp. SHUTDOWN AND LOAD DISCHARGE When the EN pin is pulled low for 1-ms, the IC stops the PWM switch and turns off the isolation switch, providing isolation between input and output. The internal current path consisting of the isolation switch’s body diode and several parasitic diodes quickly discharges the output voltage to less than 3.3-V. Afterwards, the voltage is slowly discharged to zero by the leakage current. This protects the IC and the external components from high voltage in shutdown mode. In shutdown mode, less than 1-µA of input current is consumed by the IC. OVER LOAD AND OVER VOLTAGE PROTECTION If the over load current passing through the isolation switch is above the over load limit (IOL) for 3-µs (typ), the TPS61093 is switched off until the fault is cleared and the EN pin toggles. The function only is triggered 52-ms after the IC is enabled. To prevent the PWM switch and the output capacitor from exceeding maximum voltage ratings, an over voltage protection circuit turns off the boost switch as soon as the output voltage at the VO pin exceeds the OVP threshold. Simultaneously, the IC opens the isolation switch. The regulator resumes PWM switching after the VO pin voltage falls 0.6-V below the threshold. UNDER VOLTAGE LOCKOUT (UVLO) An under voltage lockout prevents improper operation of the device for input voltages below 1.55-V. When the input voltage is below the under voltage threshold, the entire device, including the PWM and isolation switches, remains off. THERMAL SHUTDOWN An internal thermal shutdown turns off the isolation and PWM switches when the typical junction temperature of 150°C is exceeded. The thermal shutdown has a hysteresis of 15°C, typical. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS61093 9 TPS61093 SLVS992 – SEPTEMBER 2009.......................................................................................................................................................................................... www.ti.com APPLICATION INFORMATION SWITCH DUTY CYCLE The maximum switch duty cycle (D) of the TPS61093 is 90% (minimum). The duty cycle of a boost converter under continuous conduction mode (CCM) is given by: Vout + 0.8 V - Vin D= Vout + 0.8 V (1) The duty cycle must be lower than the specification in the application; otherwise the output voltage cannot be regulated. The TPS61093 has a minimum ON pulse width once the PWM switch is turned on. As the output current drops, the device enters discontinuous conduction mode (DCM). If the output current drops extremely low, causing the ON time to be reduced to the minimum ON time, the TPS61093 enters pulse-skipping mode. In this mode, the device keeps the power switch off for several switching cycles to keep the output voltage in regulation. See Figure 11. The output current when the IC enters skipping mode is calculated with Equation 2. Iout_skip = 2 Vin2 ´ Tmin_on ´ fSW 2 ´ (Vout + 0.8V - Vin) ´ L (2) Where Tmin_on = Minimum ON pulse width specification (typically 65-ns); L = Selected inductor value; fSW = Converter switching frequency (typically 1.2-MHz) OUTPUT PROGRAM To program the output voltage, select the values of R1 and R2 (see Figure 13) according to Equation 3. æ R1 ö Vout = 1.229 V ´ ç +1÷ è R2 ø æ Vout ö - 1÷ R1 = R2 ´ ç 1.229V è ø (3) A recommended value for R2 is approximately 10-kΩ which sets the current in the resistor divider chain to 1.229V/10kΩ = 123-µA. The output voltage tolerance depends on the VFB accuracy and the resistor divider. C2 C2 VO OUT TPS61093 VO Cff Option R1 C4 OUT TPS61093 FB R1 Cff Option FB R2 R2 (a) With isolation FET (b) Without isolation FET Figure 13. Resistor Divider to Program Output Voltage 10 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS61093 TPS61093 www.ti.com.......................................................................................................................................................................................... SLVS992 – SEPTEMBER 2009 WITHOUT ISOLATION FET The efficiency of the TPS61093 can be improved by connecting the load to the VO pin instead of the OUT pin. The power loss in the isolation FET is then negligible, as shown in Figure 13. The tradeoffs when bypassing the isolation FET are: • Leakage path between input and output causes the output to be a diode drop below the input voltage when the IC is in shutdown • No overload circuit protection When the load is connected to the VO pin, the output capacitor on the VO pin should be above 1-µF. 100 VIN = 4.2 V, Output = 15 V 95 90 Without isolation 85 Efficiency - % 80 With isolation 75 70 65 60 55 50 45 40 0 50 100 150 200 Load - mA 250 300 START UP The TPS61093 turns on the isolation FET and PWM switch when the EN pin is pulled high. During the soft start period, the R and C network on the SS pin is charged by an internal bias current of 5-µA (typ). The RC network sets the reference voltage ramp up slope. Since the output voltage follows the reference voltage via the FB pin, the output voltage rise time follows the SS pin voltage until the SS pin voltage reaches 0.5-V. The soft start time is given by Equation 4. 0.5 V ´ C5 tSS = 5 mA (4) Where C5 is the capacitor connected to the SS pin. When the EN pin is pulled low to switch the IC off, the SS pin voltage is discharged to zero by the resistor R3. The discharge period depends on the RC time constant. Note that if the SS pin voltage is not discharged to zero before the IC is enabled again, the soft start circuit may not slow the output voltage startup and may not reduce the startup inrush current. INDUCTOR SELECTION Because the selection of the inductor affects steady state operation, transient behavior, and loop stability, the inductor is the most important component in power regulator design. There are three important inductor specifications, inductor value, saturation current, and dc resistance. Considering inductor value alone is not enough. The saturation current of the inductor should be higher than the peak switch current as calculated in Equation 5. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS61093 11 TPS61093 SLVS992 – SEPTEMBER 2009.......................................................................................................................................................................................... www.ti.com IL_peak = IL_DC + IL_DC = DIL = D IL 2 Vout ´ Iout Vin ´ h 1 1 1 öù é æ + êL ´ ¦SW ´ ç ÷ú è Vout + 0.8 V - VIN VIN ø û ë (5) Where IL_peak = Peak switch current IL_DC = Inductor average current ΔIL = Inductor peak to peak current η = Estimated converter efficiency Normally, it is advisable to work with an inductor peak-to-peak current of less than 30% of the average inductor current. A smaller ripple from a larger valued inductor reduces the magnetic hysteresis losses in the inductor and EMI. But in the same way, load transient response time is increased. Also, the inductor value should not be outside the 2.2-µH to 10-µH range in the recommended operating conditions table. Otherwise, the internal slope compensation and loop compensation components are unable to maintain small signal control loop stability over the entire load range. Table 1 lists the recommended inductor for the TPS61093. Table 1. Recommended Inductors for the TPS61093 PART NUMBER L (µH) DCR MAX (mΩ) SATURATION CURRENT (A) SIZE (L×W×H mm) VENDOR #A915_Y-4R7M 4.7 #A915_Y-100M 10 45 1.5 5.2x5.2x3.0 Toko 90 1.09 5.2x5.2x3.0 VLS4012-4R7M Toko 4.7 132 1.1 4.0x4.0x1.2 TDK VLS4012-100M 10 240 0.82 4.0x4.0x1.2 TDK CDRH3D23/HP 10 198 1.02 4.0x4.0x2.5 Sumida LPS5030-103ML 10 127 1.4 5.0x5.0x3.0 Coilcraft INPUT AND OUTPUT CAPACITOR SELECTION The output capacitor is mainly selected to meet the requirements for output ripple and loop stability. This ripple voltage is related to the capacitor’s capacitance and its equivalent series resistance (ESR). Assuming a ceramic capacitor with zero ESR, the minimum capacitance needed for a given ripple can be calculated by: D ´ Iout Cout = Fs ´ Vripple (6) Where Vripple = peak to peak output ripple. The ESR impact on the output ripple must be considered if tantalum or electrolytic capacitors are used. Care must be taken when evaluating a ceramic capacitor’s derating under dc bias, aging, and ac signal. For example, larger form factor capacitors (in 1206 size) have their self resonant frequencies in the range of the switching frequency. So the effective capacitance is significantly lower. The dc bias can also significantly reduce capacitance. A ceramic capacitor can lose as much as 50% of its capacitance at its rated voltage. Therefore, always leave margin on the voltage rating to ensure adequate capacitance at the required output voltage. A 4.7-µF (minimum) input capacitor is recommended. The output requires a capacitor in the range of 1 µF to 10 µF. The output capacitor affects the small signal control loop stability of the boost regulator. If the output capacitor is below the range, the boost regulator can potentially become unstable. The popular vendors for high value ceramic capacitors are: • TDK (http://www.component.tdk.com/components.php) • Murata (http://www.murata.com/cap/index.html) 12 Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS61093 TPS61093 www.ti.com.......................................................................................................................................................................................... SLVS992 – SEPTEMBER 2009 SMALL SIGNAL STABILITY The TPS61093 integrates slope compensation and the RC compensation network for the internal error amplifier. Most applications will be control loop stable if the recommended inductor and input/output capacitors are used. For those few applications that require components outside the recommended values, the internal error amplifier’s gain and phase are presented in Figure 14. 80 180 VFB VEA 135 Phase 60 90 Gain - dB 45 20 Gain 0 fzea 0 fp-ea -45 Phase - deg 40 -90 -20 -135 -40 10 100 1k 10k f - Frequency - Hz 100k -180 1M Figure 14. Bode Plot of Error Amplifier Gain and Phase The RC compensation network generates a pole fp-ea of 57-kHz and a zero fz-ea of 1.9-kHz, shown in Figure 14. Use Equation 7 to calculate the output pole, fP, of the boost converter. If fP << fz-ea. due to a large capacitor beyond 10 µF, for example, a feed forward capacitor on the resistor divider, as shown in Figure 14, is necessary to generate an additional zero fz-f. to improve the loop phase margin and improve the load transient response. The low frequency pole fp-f and zero fz-f generated by the feed forward capacitor are given by Equation 8 and Equation 9: ¦P = ¦ p-f = ¦ z-f = 1 p × Ro × CO (a) (7) 1 2 p ´ R2 ´ C ff (b) 1 2 p ´ R1 ´ C ff (c) (8) (9) Where Cff = the feed-forward capacitor. For example, in the typical application circuitry (see Figure 1), the output pole fP is approximately 1-kHz. When the output capacitor is increased to 100-µF, then the fP is reduced to 10-Hz. Therefore, a feed-forward capacitor of 10-nF compensates for the low frequency pole. A feed forward capacitor that sets fz-f near 10-kHz improves the load transient response in most applications, as shown in Figure 8. Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS61093 13 TPS61093 SLVS992 – SEPTEMBER 2009.......................................................................................................................................................................................... www.ti.com LAYOUT CONSIDERATIONS As for all switching power supplies, especially those running at high switching frequency and high currents, layout is an important design step. If layout is not carefully done, the regulator could suffer from instability as well as noise problems. To maximize efficiency, switch rise and fall times are very fast. To prevent radiation of high frequency noise (e.g., EMI), proper layout of the high frequency switching path is essential. Minimize the length and area of all traces connected to the SW pin and always use a ground plane under the switching regulator to minimize interplane coupling. The high current path including the switch and output capacitor contains nanosecond rise and fall times and should be kept as short as possible. The input capacitor needs not only to be close to the VIN pin, but also to the GND pin in order to reduce input supply ripple. L1 C1 Vin C2 VO GND P al erm Th VIN CP2 C3 CP1 Minimize the area of SW trace SW Vout OUT R1 FB C4 ad SS EN R2 Place enough VIAs around thermal pad to enhace thermal performance GND R3 C5 ADDITIONAL APPLICATION 15-V Boost Converter with 100-µF Output Capacitor Vin 1.8V to 6V L1 10mH C1 TPS61093 4.7mF C3 100nF R3 200kW 14 C5 1 mF VIN SW CP1 VO CP2 OUT EN FB SS GND C2 0.1mF Vo 15V/50mA R1 294kW C6 10nF C4 100mF R2 10.2kW Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS61093 TPS61093 www.ti.com.......................................................................................................................................................................................... SLVS992 – SEPTEMBER 2009 10 V, –10 V Dual Output Boost Converter -10V/50mA Vin 3.3V L1 C4 C6 4.7mF 10mH C1 4.7mF 0.1mF TPS61093 C2 4.7mF BAT54S C3 100nF R3 200kW VIN SW CP1 VO CP2 OUT EN FB SS GND C5 1 mF 10V/50mA R1 190kW R2 10.2kW +10V OUTPUT 5V/DIV -10V OUTPUT 5V/DIV Inductor Current 500mA/DIV t - Time = 40 ms/div Figure 15. Soft Startup Waveform, 10 V, -10 V Dual Output Boost Converter Submit Documentation Feedback Copyright © 2009, Texas Instruments Incorporated Product Folder Link(s): TPS61093 15 PACKAGE OPTION ADDENDUM www.ti.com 12-Oct-2009 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Eco Plan (2) Qty TPS61093DSKR ACTIVE SON DSK 10 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS61093DSKT ACTIVE SON DSK 10 250 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. 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 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 Amplifiers Data Converters DLP® Products DSP Clocks and Timers Interface Logic Power Mgmt Microcontrollers RFID RF/IF and ZigBee® Solutions amplifier.ti.com dataconverter.ti.com www.dlp.com dsp.ti.com www.ti.com/clocks interface.ti.com logic.ti.com power.ti.com microcontroller.ti.com www.ti-rfid.com www.ti.com/lprf Applications Audio Automotive Broadband Digital Control Medical Military Optical Networking Security Telephony Video & Imaging Wireless www.ti.com/audio www.ti.com/automotive www.ti.com/broadband www.ti.com/digitalcontrol www.ti.com/medical www.ti.com/military www.ti.com/opticalnetwork www.ti.com/security www.ti.com/telephony www.ti.com/video www.ti.com/wireless Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265 Copyright © 2009, Texas Instruments Incorporated