TPS749xx www.ti.com SBVS082A – JUNE 2007 – REVISED JULY 2007 3.0A Low Dropout Linear Regulator with Programmable Soft-Start FEATURES • • • • • • • • • • • Ultra-Low VIN and VOUT Range: 0.8V to 5.5V VBIAS Range: 2.7V to 5.5V Low Dropout: 120mV (typ) at 3.0A, VBIAS = 5V Power-Good (PG) Output Allows Supply Monitoring or Provides a Sequencing Signal for Other Supplies 2% Accuracy Over Line/Load/Temperature Programmable Soft-Start Provides Linear Voltage Startup VBIAS Permits Low VIN Operation with Good Transient Response Stable with Any Output Capacitor ≥ 2.2μF Available in 5mm × 5mm × 1mm QFN and DDPAK-7 Packages Open-Drain Power-Good Active High Enable APPLICATIONS • • • • • DESCRIPTION The TPS749xx low-dropout (LDO) linear regulator provides an easy-to-use robust power management solution for a wide variety of applications. User-programmable soft-start minimizes stress on the input power source by reducing capacitive inrush current on start-up. The soft-start is monotonic and well-suited for powering many different types of processors and ASICs. The enable input and power-good output allow easy sequencing with external regulators. This complete flexibility permits the user to configure a solution that meets the sequencing requirements of FPGAs, DSPs, and other applications with special start-up requirements. A precision reference and error amplifier deliver 2% accuracy over load, line, temperature, and process. The device is stable with any type of capacitor ≥ 2.2μF, and the device is fully specified from –40°C to +125°C. The TPS749xx is offered in a small (5mm × 5mm) QFN package, yielding a highly compact total solution size. It is also available in a DDPAK-7. FPGA Applications DSP Core and I/O Voltages Post-Regulation Applications Applications with Special Start-Up Time or Sequencing Requirements Hot-Swap and Inrush Controls CSS = 0mF CSS = 0.001mF CSS = 0.0047mF 1V/div VIN IN CIN PG R3 BIAS EN VBIAS TPS74901 1.2V VEN R1 GND CSS VOUT OUT SS CBIAS VOUT COUT FB 1V/div 0V R2 Time (1ms/div) Figure 1. Typical Application Circuit (Adjustable) Figure 2. Turn-On Response 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. All trademarks are the property of their respective owners. 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 © 2007, Texas Instruments Incorporated TPS749xx www.ti.com SBVS082A – JUNE 2007 – REVISED JULY 2007 This integrated circuit can be damaged by ESD. Texas Instruments recommends that all integrated circuits be handled with appropriate precautions. Failure to observe proper handling and installation procedures can cause damage. ESD damage can range from subtle performance degradation to complete device failure. Precision integrated circuits may be more susceptible to damage because very small parametric changes could cause the device not to meet its published specifications. ORDERING INFORMATION (1) VOUT (2) PRODUCT TPS749xxyyyz (1) (2) (3) XX is nominal output voltage (for example, 12 = 1.2V, 15 = 1.5V, 01 = Adjustable). (3) YYY is package designator. Z is package quantity. For the most current package and ordering information see the Package Option Addendum at the end of this document, or see the TI website at www.ti.com. Fixed output voltages from 0.8V to 3.3V are available; minimum order quantities may apply. Contact factory for details and availability. For fixed 0.8V operation, tie FB to OUT. ABSOLUTE MAXIMUM RATINGS (1) At TJ = –40°C to +125°C, unless otherwise noted. All voltages are with respect to GND. TPS749xx UNIT VIN, VBIAS Input voltage range –0.3 to +6 V VEN Enable voltage range –0.3 to +6 V VPG Power-good voltage range –0.3 to +6 V IPG PG sink current 0 to +1.5 mA VSS SS pin voltage range –0.3 to +6 V VFB Feedback pin voltage range –0.3 to +6 V VOUT Output voltage range –0.3 to VIN + 0.3 V IOUT Maximum output current Internally limited Output short-circuit duration Indefinite PDISS Continuous total power dissipation TJ Operating junction temperature range –40 to +125 °C TSTG Storage junction temperature range –55 to +150 °C (1) See Dissipation Ratings Table 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 conditions is not implied. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. DISSIPATION RATINGS (1) (2) 2 PACKAGE θJA θJC TA < +25°C POWER RATING DERATING FACTOR ABOVE TA = +25°C RGW (QFN) (1) 36.5°C/W 4.05°C/W 2.74W 27.4mW/°C KTW (DDPAK) (2) 18.8°C/W 2.32°C/W 5.32W 53.2mW/°C See Figure 29 – Figure 31 for PCB layout description. See Figure 32 – Figure 33 for PCB layout description. Submit Documentation Feedback TPS749xx www.ti.com SBVS082A – JUNE 2007 – REVISED JULY 2007 ELECTRICAL CHARACTERISTICS At TJ = –40°C to +125°C, VEN = 1.1V, VIN = VOUT + 0.3V, CBIAS = 0.1μF, CIN = COUT = 10μF, CNR = 1nF, IOUT = 50mA, and VBIAS = 5.0V, unless otherwise noted. Typical values are at TJ = +25°C. TPS74901 PARAMETER TEST CONDITIONS MAX UNIT VIN Input voltage range VOUT + VDO 5.5 V VBIAS Bias pin voltage range 2.7 5.5 V 0.806 V 3.6 V VREF Internal reference (Adj.) TJ = +25°C 0.798 VREF Accuracy (RGW package) (1) VOUT + 2.2V ≤ VBIAS ≤ 5.5V, 50mA ≤ IOUT ≤ 3.0A –2 ±0.5 2 % Accuracy (KTW package) (1) VOUT + 2.4V ≤ VBIAS ≤ 5.5V, 50mA ≤ IOUT ≤ 3.0A –2 ±0.5 2 % VOUT/VIN Line regulation VOUT VOUT/IOUT Load regulation VDO VIN dropout voltage (2) VBIAS dropout voltage (2) ICL Current limit + 0.3 ≤ VIN ≤ 5.5V Shutdown supply current (IGND) %/V 50mA ≤ IOUT ≤ 3.0A 0.09 %/A IOUT = 3.0A, VBIAS – VOUT (NOM) ≥ 3.25V (3) 120 280 mV IOUT = 3.0A, VIN = VBIAS 1.31 1.75 V VOUT = 80% × VOUT (NOM), RGW Package 3.9 4.6 5.5 VOUT = 80% × VOUT (NOM), KTW Package 3.8 4.6 5.5 1 2 mA 1 50 μA 0.150 1 μA A VEN ≤ 0.4V IFB Feedback pin current Power-supply rejection (VIN to VOUT) PSRR Power-supply rejection (VBIAS to VOUT) Noise Output noise voltage tSTR Minimum startup time ISS Soft-start charging current –1 1kHz, IOUT = 1.5A, VIN = 1.8V, VOUT = 1.5V 60 300kHz, IOUT = 1.5A, VIN = 1.8V, VOUT = 1.5V 30 1kHz, IOUT = 1.5A, VIN = 1.8V, VOUT = 1.5V 50 300kHz, IOUT = 1.5A, VIN = 1.8V, VOUT = 1.5V 30 100Hz to 100kHz, IOUT = 3.0A, CSS = 0.001μF 25 × VOUT RLOAD for IOUT = 1.0A, CSS = open 200 μs VSS = 0.4V 440 nA VEN, HI Enable input high level VEN, VEN, LO Enable input low level HYS Enable pin hysteresis dB dB IEN Enable pin current 5.5 0 0.4 VEN = 5V VOUT decreasing 85 VHYS PG trip hysteresis VPG, LO PG output low voltage IPG, LKG PG leakage current (1) (2) (3) TJ Operating junction temperature TSD Thermal shutdown temperature μVRMS 1.1 VEN, DG Enable pin deglitch time VIT PG trip threshold 0.802 0.03 (NOM) IBIAS Bias pin current ISHDN TYP VIN = 5V, IOUT = 3.0V Output voltage range VOUT MIN V 50 mV 20 μs 0.1 1 μA 90 94 %VOUT 3 IPG = 1mA (sinking), VOUT < VIT VPG = 5.25V, VOUT > VIT V 0.1 –40 Shutdown, temperature increasing +165 Reset, temperature decreasing +140 %VOUT 0.3 V 1 μA +125 °C °C Adjustable devices tested at 0.8V; resistor tolerance is not taken into account. Dropout is defined as the voltage from VIN to VOUT when VOUT is 3% below nominal. 3.25V is a test condition of this device and can be adjusted by referring to Figure 8. Submit Documentation Feedback 3 TPS749xx www.ti.com SBVS082A – JUNE 2007 – REVISED JULY 2007 BLOCK DIAGRAM IN Current Limit BIAS UVLO OUT Thermal Limit 0.44mA VOUT R1 SS CSS Soft-Start Discharge 0.8V Reference FB PG Hysteresis and Deglitch EN R2 0.9 ´ VREF GND Table 1. Standard 1% Resistor Values for Programming the Output Voltage (1) (1) R1 (kΩ) R2 (kΩ) VOUT (V) Short Open 0.8 0.619 4.99 0.9 1.13 4.53 1.0 1.37 4.42 1.05 1.87 4.99 1.1 2.49 4.99 1.2 4.12 4.75 1.5 3.57 2.87 1.8 3.57 1.69 2.5 3.57 1.15 3.3 VOUT = 0.8 × (1 + R1/R2) Table 2. Standard Capacitor Values for Programming the Soft-Start Time (1) (1) 4 CSS SOFT-START TIME Open 0.1ms 470pF 0.5ms 1000pF 1ms 4700pF 5ms 0.01μF 10ms 0.015μF 16ms tSS(s) = 0.8 × CSS(F)/7.5 × 10 –7 Submit Documentation Feedback TPS749xx www.ti.com SBVS082A – JUNE 2007 – REVISED JULY 2007 PIN ASSIGNMENTS RGW PACKAGE QFN-20 (TOP VIEW) IN NC NC NC OUT 5 4 3 2 1 KTW PACKAGE DDPAK-7 (TOP VIEW) IN 6 20 OUT IN 7 19 OUT IN 8 18 OUT PG 9 17 NC BIAS 10 16 FB 12 13 14 15 GND NC NC SS SS FB OUT GND IN BIAS EN 11 EN 1 2 3 4 5 6 7 PIN DESCRIPTIONS NAME KTW (DDPAK) RGW (QFN) IN 5 5–8 DESCRIPTION Unregulated input to the device. EN 7 11 Enable pin. Driving this pin high enables the regulator. Driving this pin low puts the regulator into shutdown mode. This pin must not be left floating. SS 1 15 Soft-Start pin. A capacitor connected on this pin to ground sets the start-up time. If this pin is left floating, the regulator output soft-start ramp time is typically 100μs. BIAS 6 10 Bias input voltage for error amplifier, reference, and internal control circuits. PG N/A 9 Power-Good (PG) is an open-drain, active-high output that indicates the status of VOUT. When VOUT exceeds the PG trip threshold, the PG pin goes into a high-impedance state. When VOUT is below this threshold the pin is driven to a low-impedance state. A pull-up resistor from 10kΩ to 1MΩ should be connected from this pin to a supply up to 5.5V. The supply can be higher than the input voltage. Alternatively, the PG pin can be left floating if output monitoring is not necessary. FB 2 16 This pin is the feedback connection to the center tap of an external resistor divider network that sets the output voltage. This pin must not be left floating. OUT 3 1, 18–20 NC N/A 2–4, 13, 14, 17 GND 4 12 PAD/TAB Regulated output voltage. No capacitor is required on this pin for stability. No connection. This pin can be left floating or connected to GND to allow better thermal contact to the top-side plane. Ground Should be soldered to the ground plane for increased thermal performance. Submit Documentation Feedback 5 TPS749xx www.ti.com SBVS082A – JUNE 2007 – REVISED JULY 2007 TYPICAL CHARACTERISTICS At TJ = +25°C, VIN = VOUT(TYP) + 0.3V, VBIAS = 5V, IOUT = 50mA, VEN = VIN, CIN = 1μF, CBIAS = 4.7μF, and COUT = 10μF, unless otherwise noted. VBIAS LINE REGULATION 0.5 0.15 0.4 0.3 0.10 Change in VOUT (%) Change in VOUT (%) VIN LINE REGULATION 0.20 -40°C 0.05 0 +25°C -0.05 +125°C -0.01 0.2 -40°C 0.1 0 -0.1 +125°C -0.2 +25°C -0.3 -0.15 -0.4 -0.20 -0.5 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 0.5 5.0 1.0 1.5 2.0 VIN - VOUT (V) Figure 3. 3.0 3.5 4.0 Figure 4. LOAD REGULATION LOAD REGULATION 1.0 0.5 0.4 0.8 -40°C 03 0.6 Change in VOUT (%) Change in VOUT (%) 2.5 VBIAS - VOUT (V) -40°C 0.4 +125°C +25°C 0.2 +25°C 0.2 0.1 0 -0.1 -0.2 +125°C -0.3 0 -0.4 -0.2 -0.5 10 20 30 40 0.5 1.0 1.5 2.0 2.5 3.0 IOUT (mA) IOUT (A) Figure 5. Figure 6. VIN DROPOUT VOLTAGE vs iOUT AND TEMPERATURE (TJ) VIN DROPOUT VOLTAGE vs VIN DROPOUT VOLTAGE vs IOUT AND TEMPERATURE (TJ) 180 400 160 350 IOUT = 3A 140 120 100 +125°C 80 60 +25°C 40 300 250 +125°C 200 150 100 +25°C -40°C 20 50 -40°C 0 0 0 6 0 50 VDO (VIN - VOUT) (mV) VDO (VIN - VOUT) (mV) 0 0.5 1.0 1.5 2.0 2.5 3.0 1.0 1.5 2.0 2.5 3.0 IOUT (A) VBIAS - VOUT (V) Figure 7. Figure 8. Submit Documentation Feedback 3.5 4.0 4.5 TPS749xx www.ti.com SBVS082A – JUNE 2007 – REVISED JULY 2007 VIN DROPOUT VOLTAGE vs (VBIAS – VOUT) AND TEMPERATURE (TJ) 2200 200 IOUT = 0.5A 180 2000 160 VDO (VBIAS - VOUT) (mV) VDO (VIN - VOUT) (mV) VBIAS DROPOUT VOLTAGE vs IOUT AND TEMPERATURE (TJ) 140 120 100 +25°C 80 +125°C 60 40 -40°C 1800 1600 +125°C 1400 1200 +25°C 1000 -40°C 800 20 600 0 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 0 4.5 0.5 1.0 Figure 9. VBIAS PSRR vs FREQUENCY 2.5 3.0 VIN PSRR vs FREQUENCY 90 80 IOUT = 0.1A IOUT = 1.5A 70 60 50 40 IOUT = 0.5A 30 VIN = 1.8V VOUT = 1.2V VBIAS = 5V CSS = 1nF 20 10 0 10 Power-Supply Rejection Ratio (dB) Power-Supply Rejection Ratio (dB) 2.0 Figure 10. 90 80 70 IOUT = 100mA 60 IOUT = 500mA 50 40 30 20 VIN = 1.8V VOUT = 1.2V CSS = 1nF 10 0 100 1k 10k 100k 1M 10 10M Figure 12. 1kHz 10kHz 50 40 500kHz 30 100kHz 20 10 0 0.25 0.50 0.75 1.00 1.25 1.50 IOUT = 300mA 100k 1M 10M NOISE SPECTRAL DENSITY 60 0 10k Figure 11. 1.75 2.00 2.25 Output Spectral Noise Density (mV/ÖHz) 70 1k Frequency (Hz) VOUT = 1.2V IOUT = 1.5A CSS = 1nF 80 100 IOUT = 1500mA Frequency (Hz) VIN PSRR vs (VIN – VOUT) 90 Power-Supply Rejection Ratio (dB) 1.5 IOUT (A) VBIAS - VOUT (V) 1 IOUT = 100mA VOUT = 1.2V CSS = 0nF 0.1 CSS = 10nF CSS = 1nF 0.01 100 VIN - VOUT (V) 1k 10k 100k Frequency (Hz) Figure 13. Figure 14. Submit Documentation Feedback 7 TPS749xx www.ti.com SBVS082A – JUNE 2007 – REVISED JULY 2007 BIAS PIN CURRENT vs IOUT AND TEMPERATURE (TJ) BIAS PIN CURRENT vs VBIAS AND TEMPERATURE (TJ) 2.0 2.0 1.8 1.8 +125°C 1.6 1.4 1.4 IBIAS (mA) IBIAS (mA) +125°C 1.6 1.2 1.0 0.8 -40°C 0.6 1.2 +25°C 1.0 0.8 0.6 +25°C 0.4 0.4 0.2 0.2 0 -40°C 0 0 0.5 1.0 1.5 2.0 2.5 2.0 3.0 2.5 4.0 Figure 15. Figure 16. 4.5 5.0 5.5 LOW-LEVEL PG VOLTAGE vs CURRENT 1.0 500 VOL Low-Level PG Voltage (V) 475 450 425 400 375 350 325 0.9 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0 300 -50 -25 0 25 50 75 100 125 0 2 4 Junction Temperature (°C) Figure 18. CURRENT LIMIT vs (VBIAS – VOUT) 5.0 -40°C 4.5 4.0 Current Limit (A) 6 PG Current (mA) Figure 17. +125°C 3.5 3.0 +25°C 2.5 Drive capability of output FET limits IOUT when VBIAS - VOUT is under 2.0V. 2.0 1.5 VOUT = 0.8V 1.0 1.0 1.5 2.0 2.5 3.0 3.5 4.0 VBIAS - VOUT (V) Figure 19. 8 3.5 VBIAS (V) SOFT-START CHARGING CURRENT (ISS) vs TEMPERATURE (TJ) ISS (nA) 3.0 IOUT (A) Submit Documentation Feedback 4.5 5.0 8 10 12 TPS749xx www.ti.com SBVS082A – JUNE 2007 – REVISED JULY 2007 TYPICAL CHARACTERISTICS At TJ = +25°C, VIN = VOUT(TYP) + 0.3V, VBIAS = 5V, IOUT = 1A, VEN = VIN = 1.8V, VOUT = 1.5V, CIN = 1μF, CBIAS = 4.7μF, and COUT = 10μF, unless otherwise noted. VBIAS LINE TRANSIENT VIN LINE TRANSIENT CSS = 1nF COUT = 10mF (Ceramic) COUT = 10mF (Ceramic) 100mV/div 100mV/div COUT = 2.2mF (Ceramic) 100mV/div CSS = 1nF 3.8V 5.0V 1V/div 1V/div 1V/ms 3.3V 1V/ms 1.8V Time (50ms/div) Time (50ms/div) Figure 20. Figure 21. OUTPUT LOAD TRANSIENT RESPONSE TURN-ON RESPONSE COUT = 470mF (OSCON) CSS = 0nF 100mV/div COUT = 100mF (Ceramic) CSS = 1nF 0.5V/div 100mV/div VOUT CSS = 2.2nF COUT = 22mF (Ceramic) 100mV/div 1.2V 3A 1V/div VEN 0V 1A/ms 50mA Time (50ms/div) Time (1ms/div) Figure 22. Figure 23. POWER-UP/POWER-DOWN VIN = VBIAS = VEN VPG (500mV/div) 1V/div 2A/div CSS = 1nF VOUT Time (20ms/div) Figure 24. Submit Documentation Feedback 9 TPS749xx www.ti.com SBVS082A – JUNE 2007 – REVISED JULY 2007 APPLICATION INFORMATION The TPS749xx belongs to a family of low dropout regulators that feature soft-start capabilities. These regulators use a low current bias input to power all internal control circuitry, allowing the NMOS pass transistor to regulate very low input and output voltages. The use of an NMOS-pass FET offers several critical advantages for many applications. Unlike a PMOS topology device, the output capacitor has little effect on loop stability. This architecture allows the TPS749xx to be stable with any capacitor type of value 2.2μF or greater. Transient response is also superior to PMOS topologies, particularly for low VIN applications. The TPS749xx features a programmable voltage-controlled soft-start circuit that provides a smooth, monotonic start-up and limits startup inrush currents that may be caused by large capacitive loads. A power-good (PG) output is available to allow supply monitoring and sequencing of other supplies. An enable (EN) pin with hysteresis and deglitch allows slow-ramping signals to be used for sequencing the device. The low VIN and VOUT capability allows for inexpensive, easy-to-design, and efficient linear regulation between the multiple supply voltages often present in processor intensive systems. Figure 25 illustrates the typical application circuit for the TPS749xx adjustable input device. R1 and R2 can be calculated for any output voltage using the formula shown in Figure 25. Refer to Table 1 for sample resistor values of common output voltages. In order to achieve the maximum accuracy specifications, R2 should be ≤ 4.99kΩ. VIN IN CIN 1mF PG R3 BIAS EN VBIAS TPS74901 R1 SS CBIAS 1mF VOUT OUT FB GND CSS COUT 10mF R2 ( VOUT = 0.8 ´ 1 + R1 R2 INPUT, OUTPUT, AND BIAS CAPACITOR REQUIREMENTS The device is designed to be stable for all available types of and values of output capacitors ≥ 2.2μF. The device is also stable with multiple capacitors in parallel, which can be of any type or value. The capacitance required on the IN and BIAS pin strongly depends on the input supply source impedance. To counteract any inductance in the input, the minimum recommended capacitor for VIN and VBIAS is 1μF. If VIN and VBIAS are connected to the same supply, the recommended minimum capacitor for VBIAS is 4.7μF. Good quality, low ESR capacitors should be used on the input; ceramic X5R and X7R capacitors are preferred. These capacitors should be placed as close the pins as possible for optimum performance. TRANSIENT RESPONSE The TPS749xx is designed to have excellent transient response for most applications with a small amount of output capacitance. In some cases, the transient response may be limited by the transient response of the input supply. This limitation is especially true in applications where the difference between the input and output is less than 300mV. In this case, adding additional input capacitance improves the transient response much more than just adding additional output capacitance would do. With a solid input supply, adding additional output capacitance reduces undershoot and overshoot during a transient event; refer to Figure TBD in the Typical Characteristics section. Because the TPS749xx is stable with output capacitors as low as 2.2μF, many applications may need very little capacitance at the LDO output. For these applications, local bypass capacitance for the powered device may be sufficient to meet the transient requirements of the application. This design reduces the total solution cost by avoiding the need to use expensive high-value capacitors at the LDO output. ) Figure 25. Typical Application Circuit for the TPS749xx (Adjustable) 10 Submit Documentation Feedback TPS749xx www.ti.com SBVS082A – JUNE 2007 – REVISED JULY 2007 DROPOUT VOLTAGE VIN The TPS749xx offers very low dropout performance, making it well-suited for high-current low VIN/low VOUT applications. The low dropout of the TPS749xx allows the device to be used in place of a DC/DC converter and still achieve good efficiencies. This provides designers with the power architecture for their applications to achieve the smallest, simplest, and lowest cost solution. There are two different specifications for dropout voltage with the TPS749xx. The first specification (see Figure 26) is referred to as VIN Dropout and is used when an external bias voltage is applied to achieve low dropout. This specification assumes that VBIAS is at least 3.25V (1) above VOUT, which is the case for VBIAS when powered by a 5.0V rail with 5% tolerance and with VOUT = 1.5V. If VBIAS is higher than VOUT + 3.25V, VIN dropout is less than specified (1). BIAS Reference IN VBIAS = 5V ±5% VIN = 1.8V VOUT = 1.5V IOUT = 1.5A Efficiency = 83% OUT VOUT COUT FB Simplified Block Diagram Figure 26. Typical Application of the TPS749xx Using an Auxiliary Bias Rail The second specification (shown in Figure 27) is referred to as VBIAS Dropout and applied to applications where IN and BIAS are tied together. This option allows the device to be used in applications where an auxiliary bias voltage is not available or low dropout is not required. Dropout is limited by BIAS in these applications because VBIAS provides the gate drive to the pass FET; therefore, VBIAS must be 3.25V (1) above VOUT. BIAS Reference IN VBIAS = 3.3V ±5% VIN = 3.3V ± 5V VOUT = 1.5V IOUT = 1.5A Efficiency = 45% OUT VOUT COUT FB Simplified Block Diagram Figure 27. Typical Application of the TPS749xx Without an Auxiliary Bias PROGRAMMABLE SOFT-START The TPS749xx features a programmable, monotonic, voltage-controlled soft-start that is set with an external capacitor (CSS). This feature is important for many applications because it eliminates power-up initialization problems when powering FPGAs, DSPs, or other processors. The controlled voltage ramp of the output also reduces peak inrush current during start-up, minimizing start-up transient events to the input power bus. To achieve a linear and monotonic soft-start, the TPS749xx error amplifier tracks the voltage ramp of the external soft-start capacitor until the voltage exceeds the internal reference. The soft-start ramp time is dependent on the soft-start charging current (ISS), soft-start capacitance (CSS), and the internal reference voltage (VREF), and can be calculated using Equation 1: tSS = (VREF x CSS) ISS (1) If large output capacitors are used, the device current limit (ICL) and the output capacitor may set the start-up time. In this case, the start-up time is given by Equation 2: tSSCL = (VOUT(NOM) x COUT) ICL(MIN) (2) where: VOUT(NOM) is the nominal set output voltage, COUT is the output capacitance, and ICL(MIN) is the minimum current limit for the device. (1) 3.25V is a test condition of this device and can be adjusted by referring to Figure 8. In applications where monotonic startup is required, the soft-start time given by Equation 1 should be set to be greater than Equation 2. Submit Documentation Feedback 11 TPS749xx www.ti.com SBVS082A – JUNE 2007 – REVISED JULY 2007 The maximum recommended soft-start capacitor is 0.015μF. Larger soft-start capacitors can be used and will not damage the device; however, the soft-start capacitor discharge circuit may not be able to fully discharge the soft-start capacitor when enabled. Soft-start capacitors larger than 0.015μF could be a problem in applications where the user needs to rapidly pulse the enable pin and still requires the device to soft-start from ground. CSS must be low-leakage; X7R, X5R, or C0G dielectric materials are preferred. Refer to Table 2 for suggested soft-start capacitor values. VIN, VBIAS, and VEN can be sequenced in any order without causing damage to the device. However, for the soft-start function to work as intended, certain sequencing rules must be applied. Connecting EN to IN is acceptable for most applications as long as VIN is greater than 1.1V and the ramp rate of VIN and VBIAS is faster than the set soft-start ramp rate. If the ramp rate of the input sources is slower than the set soft-start time, the output tracks the slower supply minus the dropout voltage until it reaches the set output voltage. If EN is connected to BIAS, the device will soft-start as programmed, provided that VIN is present before VBIAS. If VBIAS and VEN are present before VIN is applied and the set soft-start time has expired, then VOUT tracks VIN. If the soft-start time has not expired, the output tracks VIN until VOUT reaches the value set by the charging soft-start capacitor. Figure 28 shows the use of an RC-delay circuit to hold off VEN until VBIAS has ramped. This technique can also be used to drive EN from VIN. An external control signal can also be used to enable the device after VIN and VBIAS are present. IN COUT FB R2 EN CBIAS C GND SS CSS Figure 28. Soft-Start Delay Using an RC Circuit on Enable OUTPUT NOISE The TPS749xx provides low output noise when a soft-start capacitor is used. When the device reaches the end of the soft-start cycle, the soft-start capacitor serves as a filter for the internal reference. By using a 0.001μF soft-start capacitor, the output noise is reduced by half and is typically 30μVRMS for a 1.2V output (10Hz to 100kHz). Further increasing CSS has 12 (3) The low output noise of the TPS749xx makes it a good choice for powering transceivers, PLLs, or other noise-sensitive circuitry. The enable (EN) pin is active high and is compatible with standard digital signaling levels. VEN below 0.4V turns the regulator off, while VEN above 1.1V turns the regulator on. Unlike many regulators, the enable circuitry has hysteresis and deglitching for use with relatively slowly ramping analog signals. This configuration allows the TPS749xx to be enabled by connecting the output of another supply to the EN pin. The enable circuitry typically has 50mV of hysteresis and a deglitch circuit to help avoid on-off cycling because of small glitches in the VEN signal. The enable threshold is typically 0.8V and varies with temperature and process variations. Temperature variation is approximately –1mV/°C; process variation accounts for most of the rest of the variation to the 0.4V and 1.1V limits. If precise turn-on timing is required, a fast rise-time signal must be used to enable the TPS749xx. If not used, EN can be connected to either IN or BIAS. If EN is connected to IN, it should be connected as close as possible to the largest capacitance on the input to prevent voltage droops on that line from triggering the enable circuit. POWER-GOOD R1 R VBIAS mVRMS x VOUT(V) V VOUT OUT CIN BIAS TPS74901 VN(mVRMS) = 25 ENABLE/SHUTDOWN SEQUENCING REQUIREMENTS VIN little effect on noise, Because most of the output noise is generated by the internal reference, the noise is a function of the set output voltage. The RMS noise with a 0.001μF soft-start capacitor is given in Equation 3. The power-good (PG) pin is an open-drain output and can be connected to any 5.5V or lower rail through an external pull-up resistor. This pin requires at least 1.1V on VBIAS in order to have a valid output. The PG output is high-impedance when VOUT is greater than VIT + VHYS. If VOUT drops below VIT or if VBIAS drops below 1.9V, the open-drain output turns on and pulls the PG output low. The PG pin also asserts when the device is disabled. The recommended operating condition of PG pin sink current is up to 1mA, so the pull-up resistor for PG should be in the range of 10kΩ to 1MΩ. PG is only provided on the QFN package. If output voltage monitoring is not needed, the PG pin can be left floating. Submit Documentation Feedback TPS749xx www.ti.com SBVS082A – JUNE 2007 – REVISED JULY 2007 INTERNAL CURRENT LIMIT The TPS749xx features a factory-trimmed, accurate current limit that is flat over temperature and supply voltage. The current limit allows the device to supply surges of up to 4A and maintain regulation. The current limit responds in about 10μs to reduce the current during a short-circuit fault. The internal current limit protection circuitry of the TPS749xx is designed to protect against overload conditions. It is not intended to allow operation above the rated current of the device. Continuously running the TPS749xx above the rated current degrades device reliability. THERMAL PROTECTION Thermal protection disables the output when the junction temperature rises to approximately +160°C, allowing the device to cool. When the junction temperature cools to approximately +140°C, the output circuitry is enabled. Depending on power dissipation, thermal resistance, and ambient temperature the thermal protection circuit may cycle on and off. This cycling limits the dissipation of the regulator, protecting it from damage as a result of overheating. Activation of the thermal protection circuit indicates excessive power dissipation or inadequate heatsinking. For reliable operation, junction temperature should be limited to +125°C maximum. To estimate the margin of safety in a complete design (including heatsink), increase the ambient temperature until thermal protection is triggered; use worst-case loads and signal conditions. For good reliability, thermal protection should trigger at least +40°C above the maximum expected ambient condition of the application. This condition produces a worst-case junction temperature of +125°C at the highest expected ambient temperature and worst-case load. The internal protection circuitry of the TPS749xx is designed to protect against overload conditions. It is not intended to replace proper heatsinking. Continuously running the TPS749xx into thermal shutdown degrades device reliability. LAYOUT RECOMMENDATIONS AND POWER DISSIPATION An optimal layout can greatly improve transient performance, PSRR, and noise. To minimize the voltage drop on the input of the device during load transients, the capacitance on IN and BIAS should be connected as close as possible to the device. This capacitance also minimizes the effects of parasitic inductance and resistance of the input source and can therefore improve stability. To achieve optimal transient performance and accuracy, the top side of R1 in Figure 25 should be connected as close as possible to the load. If BIAS is connected to IN it is recommended to connect BIAS as close to the sense point of the input supply as possible. This connection minimizes the voltage droop on BIAS during transient conditions and can improve the turn-on response. Knowing the device power dissipation and proper sizing of the thermal plane that is connected to the tab or pad is critical to avoiding thermal shutdown and ensuring reliable operation. Power dissipation of the device depends on input voltage and load conditions and can be calculated using Equation 4: PD = (VIN - VOUT) x IOUT (4) Power dissipation can be minimized and greater efficiency can be achieved by using the lowest possible input voltage necessary to achieve the required output voltage regulation. On both the QFN (RGW) and DDPAK (KTW) packages, the primary conduction path for heat is through the exposed pad or tab to the printed circuit board (PCB). The pad or tab can be connected to ground or be left floating; however, it should be attached to an appropriate amount of copper PCB area to ensure the device will not overheat. The maximum junction to ambient thermal resistance depends on the maximum ambient temperature, maximum device junction temperature, and power dissipation of the device and can be calculated using Equation 5: RqJA = (+125°C - TA) PD (5) Knowing the maximum RθJA, and system air flow the minimum amount of PCB copper area needed for appropriate heatsinking can be calculated using Figure 29 through Figure 31. Submit Documentation Feedback 13 TPS749xx www.ti.com SBVS082A – JUNE 2007 – REVISED JULY 2007 PCB Top View PCB Cross Section TJ RqJC TC RqCS 0.062in. TS RqSA 4-layer. 0.062” FR4 Vias are 0.012” diameter, plated Top/Bottom layers are 2 oz. copper Inner layers are 1 oz. copper 0.5in TA 1.0in RqJA = RqJC + RqCS + RqSA 2.0in 2 2 2 55 50 0 LFM qJA (°C/W) 45 40 150 LFM 35 250 LFM 30 25 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 2 Area (in ) Figure 29. RGW (5 x 5 QFN) PCB Layout and Corresponding RθJA Data, Buried Thermal Plane, No Vias Under Thermal Pad 14 Submit Documentation Feedback TPS749xx www.ti.com SBVS082A – JUNE 2007 – REVISED JULY 2007 PCB Top View PCB Cross Section TJ RqJC TC RqCS 0.062in. TS 0.5in RqSA 4-layer. 0.062” FR4 Vias are 0.012” diameter, plated Top/Bottom layers are 2 oz. copper Inner layers are 1 oz. copper 1.0in TA 2.0in 2 2 2 RqJA = RqJC + RqCS + RqSA 50 45 0 LFM qJA (°C/W) 40 150 LFM 35 30 250 LFM 25 20 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 2 Area (in ) Figure 30. RGW (5 x 5 QFN) PCB Layout and Corresponding RθJA Data, Buried Thermal Plane, Vias Under Thermal Pad Submit Documentation Feedback 15 TPS749xx www.ti.com SBVS082A – JUNE 2007 – REVISED JULY 2007 PCB Top View PCB Cross Section TJ RqJC TC RqCS 0.062in. TS 4-layer. 0.062” FR4 Vias are 0.012” diameter, plated Top/Bottom layers are 2 oz. copper Inner layers are 1 oz. copper RqSA 0.5in TA 1.0in 2.0in 2 2 2 RqJA = RqJC + RqCS + RqSA 90 80 qJA (°C/W) 70 0 LFM 60 150 LFM 50 40 250 LFM 30 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 2 Area (in ) Figure 31. RGW (5 x 5 QFN) PCB Layout and Corresponding RθJA Data, Top Layer Thermal Plane 16 Submit Documentation Feedback TPS749xx www.ti.com SBVS082A – JUNE 2007 – REVISED JULY 2007 PCB Top View PCB Cross Section 2.0in 2 TJ RqJC 1.0in 2 TC 0.5in RqCS 0.062in. 2 TS RqSA 4-layer. 0.062” FR4 Vias are 0.012” diameter, plated Top/Bottom layers are 2 oz. copper Inner layers are 1 oz. copper TA RqJA = RqJC + RqCS + RqSA 35 0 LFM qJA (°C/W) 30 25 20 15 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 2 Area (in ) Figure 32. KTW (DDPAK-7) PCB Layout and Corresponding RθJA, Buried Thermal Plane Submit Documentation Feedback 17 TPS749xx www.ti.com SBVS082A – JUNE 2007 – REVISED JULY 2007 PCB Top View PCB Cross Section 2.0in 2 TJ 1.0in RqJC TC 2 0.5in 2 RqCS 0.062in. TS RqSA 4-layer. 0.062” FR4 Vias are 0.012” diameter, plated Top/Bottom layers are 2 oz. copper Inner layers are 1 oz. copper TA RqJA = RqJC + RqCS + RqSA 55 50 45 qJA (°C/W) 40 35 30 0 LFM 25 20 15 10 0 0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0 4.5 2 Area (in ) Figure 33. KTW (DDPAK-7) PCB Layout and Corresponding RθJA, Top Layer Thermal Plane 18 Submit Documentation Feedback PACKAGE OPTION ADDENDUM www.ti.com 26-Jul-2007 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Eco Plan (2) Qty TPS74901KTWR ACTIVE DDPAK KTW 7 500 Green (RoHS & no Sb/Br) CU SN Level-2-260C-1 YEAR TPS74901KTWT ACTIVE DDPAK KTW 7 50 Green (RoHS & no Sb/Br) CU SN Level-2-260C-1 YEAR TPS74901RGWR ACTIVE QFN RGW 20 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS74901RGWRG4 ACTIVE QFN RGW 20 3000 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS74901RGWT ACTIVE QFN RGW 20 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS74901RGWTG4 ACTIVE QFN RGW 20 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR 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 PACKAGE MATERIALS INFORMATION www.ti.com 24-Jul-2007 TAPE AND REEL INFORMATION Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com Device 24-Jul-2007 Package Pins Site Reel Diameter (mm) Reel Width (mm) A0 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant TPS74901KTWR KTW 7 MLA 330 24 10.6 15.6 4.9 16 24 Q2 TPS74901KTWT KTW 7 MLA 330 24 10.6 15.6 4.9 16 24 Q2 TPS74901RGWR RGW 20 MLA 330 12 5.3 5.3 1.5 8 12 Q2 TPS74901RGWT RGW 20 MLA 180 12 5.3 5.3 1.5 8 12 Q2 TAPE AND REEL BOX INFORMATION Device Package Pins Site Length (mm) Width (mm) Height (mm) TPS74901KTWR KTW 7 MLA 346.0 346.0 41.0 41.0 TPS74901KTWT KTW 7 MLA 346.0 346.0 TPS74901RGWR RGW 20 MLA 346.0 346.0 29.0 TPS74901RGWT RGW 20 MLA 190.0 212.7 31.75 Pack Materials-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 24-Jul-2007 Pack Materials-Page 3 MECHANICAL DATA MPSF015 – AUGUST 2001 KTW (R-PSFM-G7) PLASTIC FLANGE-MOUNT 0.410 (10,41) 0.385 (9,78) 0.304 (7,72) –A– 0.006 –B– 0.303 (7,70) 0.297 (7,54) 0.0625 (1,587) H 0.055 (1,40) 0.0585 (1,485) 0.300 (7,62) 0.064 (1,63) 0.045 (1,14) 0.252 (6,40) 0.056 (1,42) 0.187 (4,75) 0.370 (9,40) 0.179 (4,55) 0.330 (8,38) H 0.296 (7,52) A 0.605 (15,37) 0.595 (15,11) 0.012 (0,305) C 0.000 (0,00) 0.019 (0,48) 0.104 (2,64) 0.096 (2,44) H 0.017 (0,43) 0.050 (1,27) C C F 0.034 (0,86) 0.022 (0,57) 0.010 (0,25) M B 0.026 (0,66) 0.014 (0,36) 0°~3° AM C M 0.183 (4,65) 0.170 (4,32) 4201284/A 08/01 NOTES: A. All linear dimensions are in inches (millimeters). B. This drawing is subject to change without notice. C. Lead width and height dimensions apply to the plated lead. D. Leads are not allowed above the Datum B. E. Stand–off height is measured from lead tip with reference to Datum B. F. Lead width dimension does not include dambar protrusion. Allowable dambar protrusion shall not cause the lead width to exceed the maximum dimension by more than 0.003”. G. Cross–hatch indicates exposed metal surface. H. Falls within JEDEC MO–169 with the exception of the dimensions indicated. POST OFFICE BOX 655303 • DALLAS, TEXAS 75265 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, modifications, enhancements, improvements, and other changes to its products and services at any time and to discontinue any product or service without notice. Customers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All products are sold subject to TI’s terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its hardware products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where mandated by government requirements, testing of all parameters of each product is not necessarily performed. TI assumes no liability for applications assistance or customer product design. Customers are responsible for their products and applications using TI components. To minimize the risks associated with customer products and applications, customers should provide adequate design and operating safeguards. TI does not warrant or represent that any license, either express or implied, is granted under any TI patent right, copyright, mask work right, or other TI intellectual property right relating to any combination, machine, or process in which TI products or services are used. Information published by TI regarding third-party products or services does not constitute a license from TI to use such products or services or a warranty or endorsement thereof. Use of such information may require a license from a third party under the patents or other intellectual property of the third party, or a license from TI under the patents or other intellectual property of TI. Reproduction of TI information in TI data books or data sheets is permissible only if reproduction is without alteration and is accompanied by all associated warranties, conditions, limitations, and notices. Reproduction of this information with alteration is an unfair and deceptive business practice. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional restrictions. Resale of TI products or services with statements different from or beyond the parameters stated by TI for that product or service voids all express and any implied warranties for the associated TI product or service and is an unfair and deceptive business practice. TI is not responsible or liable for any such statements. TI products are not authorized for use in safety-critical applications (such as life support) where a failure of the TI product would reasonably be expected to cause severe personal injury or death, unless officers of the parties have executed an agreement specifically governing such use. Buyers represent that they have all necessary expertise in the safety and regulatory ramifications of their applications, and acknowledge and agree that they are solely responsible for all legal, regulatory and safety-related requirements concerning their products and any use of TI products in such safety-critical applications, notwithstanding any applications-related information or support that may be provided by TI. Further, Buyers must fully indemnify TI and its representatives against any damages arising out of the use of TI products in such safety-critical applications. TI products are neither designed nor intended for use in military/aerospace applications or environments unless the TI products are specifically designated by TI as military-grade or "enhanced plastic." Only products designated by TI as military-grade meet military specifications. Buyers acknowledge and agree that any such use of TI products which TI has not designated as military-grade is solely at the Buyer's risk, and that they are solely responsible for compliance with all legal and regulatory requirements in connection with such use. TI products are neither designed nor intended for use in automotive applications or environments unless the specific TI products are designated by TI as compliant with ISO/TS 16949 requirements. Buyers acknowledge and agree that, if they use any non-designated products in automotive applications, TI will not be responsible for any failure to meet such requirements. Following are URLs where you can obtain information on other Texas Instruments products and application solutions: Products Applications Amplifiers amplifier.ti.com Audio www.ti.com/audio Data Converters dataconverter.ti.com Automotive www.ti.com/automotive DSP dsp.ti.com Broadband www.ti.com/broadband Interface interface.ti.com Digital Control www.ti.com/digitalcontrol Logic logic.ti.com Military www.ti.com/military Power Mgmt power.ti.com Optical Networking www.ti.com/opticalnetwork Microcontrollers microcontroller.ti.com Security www.ti.com/security RFID www.ti-rfid.com Telephony www.ti.com/telephony Low Power Wireless www.ti.com/lpw Video & Imaging www.ti.com/video Wireless www.ti.com/wireless Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265 Copyright © 2007, Texas Instruments Incorporated