TPS794xx www.ti.com SLVS349E - NOVEMBER 2001 - REVISED DECEMBER 2005 ULTRALOW-NOISE, HIGH-PSRR, FAST, RF, 250-mA LOW-DROPOUT LINEAR REGULATORS FEATURES * * * * * * * 250-mA Low-Dropout Regulator With Enable Available in Fixed and Adjustable (1.2 V to 5.5 V) Versions High PSRR (60 dB at 10 kHz) Ultralow Noise (32 Vrms, TPS79428) Fast Start-Up Time (50 s) Stable With a 2.2-F Ceramic Capacitor Excellent Load/Line Transient Response Very Low Dropout Voltage (155 mV at Full Load) Available in MSOP-8 and SOT223-6 Packages The TPS794xx family of low-dropout (LDO) linear voltage regulators features high power-supply rejection ratio (PSRR), ultralow-noise, fast start-up, and excellent line and load transient responses in small outline, MSOP-8 PowerPADTM and SOT223-6 packages. Each device in the family is stable with a small 2.2-F ceramic capacitor on the output. The family uses an advanced, proprietary BiCMOS fabrication process to yield extremely low dropout voltages (for example, 155 mV at 250 mA). Each device achieves fast start-up times (approximately 50 s with a 0.001-F bypass capacitor) while consuming low quiescent current (170 A typical). Moreover, when the device is placed in standby mode, the supply current is reduced to less than 1 A. The TPS79428 exhibits approximately 32 VRMS of output voltage noise at 2.8 V output with a 0.1-F bypass capacitor. Applications with analog components that are noise-sensitive, such as portable RF electronics, benefit from the high PSRR and low noise features as well as the fast response time. APPLICATIONS * * * * * RF: VCOs, Receivers, ADCs Audio BluetoothTM, Wireless LAN Cellular and Cordless Telephones Handheld Organizers, PDAs DGN PACKAGE MSOP-8 PowerPADt (TOP VIEW) 1 OUT 8 IN 2 7 NC NC 3 6 FB EN 4 5 NR GND DCQ PACKAGE SOT223-6 (TOP VIEW) EN IN GND OUT NR/FB 1 2 3 4 5 0.35 80 IOUT = 10 mA 70 IOUT = 250 mA 60 50 40 30 VIN = 4.3 V, VOUT = 3.3 V, CIN = 1 F, COUT = 10 F, CNR = 0.01 F 20 6 GND TPS79428 OUTPUT SPECTRAL NOISE DENSITY vs FREQUENCY 90 Ripple Rejection (dB) NC - No internal connection TPS79433 RIPPLE REJECTION vs FREQUENCY Output Spectral Noise Density (V/Hz) * * DESCRIPTION 10 0 10 100 1k COUT = 2.2 F, CNR = 0.1 F, VIN = 3.8 V 0.30 0.25 IOUT = 250 mA 0.20 0.15 0.10 IOUT = 1 mA 0.05 0 10 k 100 k Frequency (Hz) 1M 10 M 100 1000 10000 100000 Frequency (Hz) 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. PowerPAD is a trademark of Texas Instruments. Bluetooth is a trademark of Bluetooth SIG, Inc. All other 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 (c) 2001-2005, Texas Instruments Incorporated TPS794xx www.ti.com SLVS349E - NOVEMBER 2001 - REVISED DECEMBER 2005 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 TPS794xxyyyz (1) (2) XX is nominal output voltage (for example, 28 = 2.8 V, 285 = 2.85 V, 01 = Adjustable). 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. Output voltages from 1.3 V to 5.0 V in 100 mV increments are available; minimum order quantities may apply. Contact factory for details and availability. ABSOLUTE MAXIMUM RATINGS over operating temperature range unless otherwise noted (1) VALUE VIN range -0.3 V to 6 V VEN range -0.3 V to VIN + 0.3 V VOUT range -0.3 V to 6 V Peak output current Internally limited ESD rating, HBM 2 kV ESD rating, CDM 500 V Continuous total power dissipation See Dissipation Ratings Table Junction temperature range, TJ -40C to +150C Storage temperature range, Tstg -65C to +150C (1) 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. PACKAGE DISSIPATION RATINGS PACKAGE AIR FLOW (CFM) RJC (C/W) RJA (C/W) TA 25C POWER RATING TA = 70C POWER RATING TA = 85C POWER RATING 0 8.47 55.09 2.27 W 1.45 W 1.18 W DGN 150 8.21 49.97 2.50 W 1.60 W 1.30 W 250 8.20 48.10 2.60 W 1.66 W 1.35 W 6 5 PD (W) 4 Condition 1 3 Condition 2 2 CONDITIONS PACKAGE 1 2 SOT223 SOT223 PCB AREA 4in2 Top Side Only 0.5in2 Top Side Only 1 0 0 25 50 75 100 TA (C) 125 150 Figure 1. SOT223 Power Dissipation 2 Submit Documentation Feedback JA 53C/W 110C/W TPS794xx www.ti.com SLVS349E - NOVEMBER 2001 - REVISED DECEMBER 2005 ELECTRICAL CHARACTERISTICS Over recommended operating temperature range (TJ = -40C to 125C), VEN = VIN, VIN = VOUT(nom) + 1 V (1), IOUT = 1mA, COUT = 10F, CNR = 0.01 F, unless otherwise noted. Typical values are at 25C. PARAMETER TEST CONDITIONS MIN Input voltage, VIN (1) Continuous output current, IOUT Output voltage range Output voltage Accuracy TPS79401 V 250 mA 1.225 5.5 - VDO 0 A IOUT 250 mA, VOUT + 1 V VIN 5.5 0.97(VOUT) Fixed VOUT 0 A IOUT 250 mA, VOUT + 1 V VIN 5.5 V (1) -3.0 VOUT + 1 V VIN 5.5 V 0 A IOUT 250 mA UNIT 0 V (1) Load regulation (VOUT%/IOUT) MAX 5.5 TPS79401 (2) Output voltage line regulation (VOUT%/VIN) (1) TYP 2.7 VOUT 0.05 V 1.03(VOUT) V +3.0 % 0.12 %/V 10 mV TPS79428 IOUT = 250 mA 155 210 TPS79430 IOUT = 250 mA 155 210 TPS79433 IOUT = 250 mA 145 200 Output current limit VOUT = 0 V 925 Ground pin current 0 A IOUT 250 mA 170 220 A Shutdown current (4) VEN = 0 V, 2.7 V VIN 5.5 V 0.07 1 A FB pin current VFB = 1.225 V 1 A Dropout voltage (3) VIN = VOUT(nom)- 0.1 V Power-supply ripple rejection Output noise voltage Time, start-up TPS79428 TPS79428 TPS79428 f = 100 Hz, IOUT = 250 mA 65 f = 10 kHz, IOUT = 250 mA 60 f = 100 kHz, IOUT = 250 mA 40 BW = 100 Hz to 100 kHz, IOUT = 250 mA RL = 14 , COUT = 1 F CNR = 0.001 F 55 CNR = 0.0047 F 36 CNR = 0.01 F 33 CNR = 0.1 F 32 CNR = 0.001 F 50 CNR = 0.0047 F 70 CNR = 0.01 F mV mA dB VRMS s 100 High-level enable input voltage 2.7 V VIN 5.5 V 1.7 VIN Low-level enable input voltage 2.7 V VIN 5.5 V 0 0.7 V EN pin current VEN = 0 1 1 A UVLO threshold VCC rising UVLO hysteresis (1) (2) (3) (4) 2.25 2.65 100 V V mV Minimum VIN is 2.7 V or VOUT + VDO, whichever is greater. Tolerance of external resistors not included in this specification. Dropout is not measured for the TPS79418 and TPS79425 since minimum VIN = 2.7 V. For adjustable versions, this applies only after VIN is applied; then VEN transitions high to low. Submit Documentation Feedback 3 TPS794xx www.ti.com SLVS349E - NOVEMBER 2001 - REVISED DECEMBER 2005 FUNCTIONAL BLOCK DIAGRAM--ADJUSTABLE VERSION OUT IN Current Sense UVLO SHUTDOWN ILIM _ GND R1 + FB EN UVLO R2 Thermal Shutdown Quickstart Bandgap Reference 1.225 V VIN 250 k External to the Device Vref NR(1) (1) Not Available on DCQ (SOT223) options. FUNCTIONAL BLOCK DIAGRAM--FIXED VERSION OUT IN UVLO Current Sense GND SHUTDOWN ILIM _ EN + R1 UVLO Thermal Shutdown R2 Quickstart VIN R2 = 40k Bandgap Reference 1.225 V 250 k Vref NR Terminal Functions TERMINAL 4 DESCRIPTION NAME DGN (MSOP) DCQ (SOT223) NR 4 5 Connecting an external capacitor to this pin bypasses noise generated by the internal bandgap, which improves power-supply rejection and reduces output noise. EN 6 1 The EN terminal is an input that enables or shuts down the device. When EN is a logic high, the device is enabled. When the device is a logic low, the device is in shutdown mode. FB 3 5 Feedback input voltage for the adjustable device. GND 5, PAD 3, 6 IN 8 2 NC 2, 7 OUT 1 Regulator ground Unregulated input to the device. No internal connection. 4 Regulator output Submit Documentation Feedback TPS794xx www.ti.com SLVS349E - NOVEMBER 2001 - REVISED DECEMBER 2005 TYPICAL CHARACTERISTICS TPS79433 OUTPUT VOLTAGE vs OUTPUT CURRENT TPS79428 OUTPUT VOLTAGE vs JUNCTION TEMPERATURE 3.290 TPS79428 GROUND CURRENT vs JUNCTION TEMPERATURE 190 2.800 3.285 IOUT = 1 mA 2.795 VIN = 3.8 V, COUT = 10 F 185 3.280 180 IOUT = 1 mA 3.270 3.265 3.255 2.780 2.765 50 100 IOUT (mA) 200 250 -40 -25 -10 5 155 150 -40 -25 -10 5 20 35 50 65 80 95 110 125 TJ (C) Figure 4. TPS79428 OUTPUT SPECTRAL NOISE DENSITY vs FREQUENCY TPS79428 OUTPUT SPECTRAL NOISE DENSITY vs FREQUENCY TPS79428 OUTPUT SPECTRAL NOISE DENSITY vs FREQUENCY 0.35 Output Spectral Noise Density (V/Hz) 0.30 0.25 0.20 IOUT = 250 mA 0.15 0.10 IOUT = 1 mA 0.05 0 1.8 COUT = 10 F, CNR = 0.1 F, VIN = 3.8 V 0.30 0.25 0.20 IOUT = 1 mA 0.15 0.10 IOUT = 250 mA 0.05 1000 10000 100000 100 1000 10000 COUT = 10 F, IOUT = 250 mA VIN = 3.8 V 1.6 1.4 CNR = 0.001 F 1.2 CNR = 0.0047 F 1.0 CNR = 0.01 F 0.8 CNR = 0.1 F 0.6 0.4 0.2 0 100 0 100000 1000 10000 100000 Frequency (Hz) Frequency (Hz) Frequency (Hz) Figure 5. Figure 6. Figure 7. TPS79428 ROOT MEAN SQUARED OUTPUT NOISE vs CNR TPS79433 OUTPUT IMPEDANCE vs FREQUENCY TPS79428 DROPOUT VOLTAGE vs JUNCTION TEMPERATURE 10 60 250 VIN = 3.8 V, COUT = 10 F VIN = 4.3 V, COUT = 10 F, 30 20 200 IOUT = 250 mA IOUT = 1 mA 1 VDO (mV) ZO, Output Impedance () IOUT = 250 mA, COUT = 10 F 40 Figure 8. 0.1 100 50 IOUT = 1 mA 0.020 0.0047 0.01 CNR (F) 150 IOUT = 250 mA 0.100 10 0 0.001 20 35 50 65 80 95 110 125 TJ (C) Figure 3. COUT = 2.2 F, CNR = 0.1 F, VIN = 3.8 V 50 IOUT = 250 mA Figure 2. 0.35 100 170 160 IOUT = 200 mA Output Spectral Noise Density (V/Hz) 0 175 165 2.770 3.250 Output Spectral Noise Density (V/Hz) 2.785 2.775 3.260 RMS Output Noise (VRMS) VIN = 3.8 V COUT = 10 F IGND (A) 3.275 V OUT (V) V OUT (V) 2.790 10 100 1k 10 k 100 k 1M Frequency (Hz) Figure 9. Submit Documentation Feedback 10 M 0 -40 -25 -10 5 20 35 50 65 80 95 110 125 TJ (C) Figure 10. 5 TPS794xx www.ti.com SLVS349E - NOVEMBER 2001 - REVISED DECEMBER 2005 TYPICAL CHARACTERISTICS (continued) TPS79433 RIPPLE REJECTION vs FREQUENCY TPS79433 RIPPLE REJECTION vs FREQUENCY 80 70 Ripple Rejection (dB) IOUT = 10 mA IOUT = 250 mA 60 50 40 VIN = 4.3 V, VOUT = 3.3 V, CIN = 1 F, COUT = 10 F, CNR = 0.01 F 10 10 100 50 40 VIN = 4.3 V, VOUT = 3.3 V, CIN = 1 F, COUT = 2.2 F, CNR = 0.01 F 20 10 10 k 100 k 1M 10 10 M 10 10 k 100 k 1M 0 10 M 10 100 1k 10 k 100 k Figure 13. TPS79433 OUTPUT VOLTAGE, ENABLE VOLTAGE vs TIME (START-UP) TPS79433 LINE TRANSIENT RESPONSE TPS79433 LOAD TRANSIENT RESPONSE VIN (V) VIN = 4.3 V, VOUT = 3.3 V, IOUT = 250 mA, COUT = 2.2 F IOUT = 250 mA,COUT = 10 F, CNR = 0.1 F, dv/dt = 1 V/s 5.5 10 M Frequency (Hz) 5.0 250 50 0 4.5 10 3 CNR = 0.0047 F 2 CNR = 0.001 F 1 0 -10 0 -50 -20 0 0 80 160 240 320 400 480 560 640 720 800 100 200 300 400 0 500 30 60 90 120 + 0.02A ms 150 180 Time (s) Time (s) Figure 14. Figure 15. Figure 16. TPS79425 POWER-UP/ POWER-DOWN TPS79433 DROPOUT VOLTAGE vs OUTPUT CURRENT TPS79401 DROPOUT VOLTAGE vs INPUT VOLTAGE Time (s) 4.5 210 250 200 VOUT = 2.5 V, RL = 10 4.0 di dt VIN = 4.3 V, COUT = 10 F -30 0 TA = 125C TA = 125C TA = 25C 200 3.5 150 VIN 3.0 VDO (mV) VOUT 2.0 1.5 VDO (mV) TA = 25C 2.5 100 150 100 TA = -40C TA = -40C 1.0 50 COUT = 10 F, CNR = 0.01 F, IOUT = 250 mA 50 0.5 0 -0.5 0 0 1.4 2.8 4.2 5.6 t (ms) Figure 17. 6 1M Figure 12. VOUT (mV) VOUT, VEN (V) VIN = 4.3 V, VOUT = 3.3 V, CIN = 1 F, COUT = 2.2 F, CNR = 0.1 F Figure 11. 6.0 Power-Up (500 mV/div) 30 Frequency (Hz) V_Enable 0 1k 40 Frequency (Hz) 4 2 100 50 20 0 1k IOUT = 250 mA 60 IOUT (mA) 20 70 IOUT = 250 mA 60 VOUT (mV) 30 70 30 IOUT = 10 mA 80 IOUT = 10 mA Ripple Rejection (dB) 80 Ripple Rejection (dB) 90 90 90 0 TPS79433 RIPPLE REJECTION vs FREQUENCY 7.0 8.4 9.8 0 25 50 75 100 125 150 175 200 225 250 IOUT (mA) Figure 18. Submit Documentation Feedback 0 2.5 3.0 3.5 4.0 VIN (V) Figure 19. 4.5 5.0 TPS794xx www.ti.com SLVS349E - NOVEMBER 2001 - REVISED DECEMBER 2005 TYPICAL CHARACTERISTICS (continued) TPS79428 TYPICAL REGIONS OF STABILITY EQUIVALENT SERIES RESISTANCE (ESR) vs OUTPUT CURRENT 100 COUT = 2.2 F TA = -40 to 85C 10 Region of Instability 1 0.1 Region of Stability 0.01 ESR, Equivalent Series Resistance () ESR, Equivalent Series Resistance () 100 TPS79428 TYPICAL REGIONS OF STABILITY EQUIVALENT SERIES RESISTANCE (ESR) vs OUTPUT CURRENT COUT = 10 F TA = -40 to 85C 10 Region of Instability 1 0.1 Region of Stability 0.01 0 25 50 75 100 125 150 175 200 225 250 IOUT (mA) 1 10 Figure 20. Submit Documentation Feedback 20 40 60 80 IOUT (mA) 120 200 250 Figure 21. 7 TPS794xx www.ti.com SLVS349E - NOVEMBER 2001 - REVISED DECEMBER 2005 APPLICATION INFORMATION The TPS794xx family of low-dropout (LDO) regulators has been optimized for use in noise-sensitive equipment. The device features extremely low dropout voltages, high PSRR, ultralow output noise, low quiescent current (265 A typically), and an enable input to reduce supply currents to less than 1 A when the regulator is turned off. A typical application circuit is shown in Figure 22. VIN IN VOUT OUT TPS794xx 1 F EN GND 2.2F NR 0.01F Figure 22. Typical Application Circuit EXTERNAL CAPACITOR REQUIREMENTS A 1-F or larger ceramic input bypass capacitor, connected between IN and GND and located close to the TPS794xx, is required for stability and improves transient response, noise rejection, and ripple rejection. A higher-value input capacitor may be necessary if large, fast-rise-time load transients are anticipated and the device is located several inches from the power source. order for the regulator to operate properly, the current flow out of the NR pin must be at a minimum, because any leakage current creates an IR drop across the internal resistor, thus creating an output error. Therefore, the bypass capacitor must have minimal leakage current. The bypass capacitor should be no more than 0.1-F in order to ensure that it is fully charged during the quickstart time provided by the internal switch shown in the Functional Block Diagram. For example, the TPS79430 exhibits only 33 VRMS of output voltage noise using a 0.1-F ceramic bypass capacitor and a 10-F ceramic output capacitor. Note that the output starts up slower as the bypass capacitance increases because of the RC time constant at the bypass pin that is created by the internal 250-k resistor and external capacitor. BOARD LAYOUT RECOMMENDATION TO IMPROVE PSRR AND NOISE PERFORMANCE To improve ac measurements such as PSRR, output noise, and transient response, it is recommended that the board be designed with separate ground planes for VIN and VOUT, with each ground plane connected only at the ground pin of the device. In addition, the ground connection for the bypass capacitor should connect directly to the ground pin of the device. REGULATOR MOUNTING Like most low-dropout regulators, the TPS794xx requires an output capacitor connected between OUT and GND to stabilize the internal control loop. The minimum recommended capacitance is 1 F. Any 1 F or larger ceramic capacitor is suitable. The tab of the SOT223-6 package is electrically connected to ground. For best thermal performance, the tab of the surface-mount version should be soldered directly to a circuit-board copper area. Increasing the copper area improves heat dissipation. The internal voltage reference is a key source of noise in an LDO regulator. The TPS794xx has an NR pin which is connected to the voltage reference through a 250-k internal resistor. The 250-k internal resistor, in conjunction with an external bypass capacitor connected to the NR pin, creates a low-pass filter to reduce the voltage reference noise and, therefore, the noise at the regulator output. In Solder pad footprint recommendations for the devices are presented in Application Report SBFA015, Solder Pad Recommendations for Surface-Mount Devices, available from the TI web site (www.ti.com). 8 Submit Documentation Feedback TPS794xx www.ti.com SLVS349E - NOVEMBER 2001 - REVISED DECEMBER 2005 PROGRAMMING THE TPS79401 ADJUSTABLE LDO REGULATOR In order to improve the stability of the adjustable version, it is suggested that a small compensation capacitor be placed between OUT and FB. The output voltage of the TPS79401 adjustable regulator is programmed using an external resistor divider as shown in Figure 23. The output voltage is calculated using Equation 1: V OUT + VREF 1 ) RR The approximate value of this capacitor can be calculated as Equation 3: (3 10 *7) (R 1 ) R 2) C1 + (R 1 R 2) (3) 1 2 (1) The suggested value of this capacitor for several resistor ratios is shown in the table within Figure 23. If this capacitor is not used (such as in a unity-gain configuration), then the minimum recommended output capacitor is 2.2 F instead of 1 F. where: * VREF = 1.2246 V typ (the internal reference voltage) Resistors R1 and R2 should be chosen for approximately 40-A divider current. Lower value resistors can be used for improved noise performance, but the device wastes more power. Higher values should be avoided, as leakage current at FB increases the output voltage error. REGULATOR PROTECTION The TPS794xx PMOS-pass transistor has a built-in back diode that conducts reverse current when the input voltage drops below the output voltage (for example, during power down). Current is conducted from the output to the input and is not internally limited. If extended reverse voltage operation is anticipated, external limiting might be appropriate. The recommended design procedure is to choose R2 = 30.1 k to set the divider current at 40 A, C1 = 15 pF for stability, and then calculate R1 using Equation 2: VOUT R1 + *1 R2 VREF VIN (2) IN 1 F The TPS794xx features internal current limiting and thermal protection. During normal operation, the TPS794xx limits output current to approximately 2.8 A. When current limiting engages, the output voltage scales back linearly until the overcurrent condition ends. While current limiting is designed to prevent gross device failure, care should be taken not to exceed the power dissipation ratings of the package. If the temperature of the device exceeds approximately 165C, thermal-protection circuitry shuts it down. Once the device has cooled down to below approximately 140C, regulator operation resumes. OUT TPS79401 EN GND OUTPUT VOLTAGE PROGRAMMING GUIDE VOUT R1 C1 2.2 F OUTPUT VOLTAGE R1 R2 C1 1.8 V 14.0 k 30.1 k 22 pF 3.6 V 61.9 k 30.1 k 15 pF FB R2 Figure 23. TPS79401 Adjustable LDO Regulator Programming Submit Documentation Feedback 9 TPS794xx www.ti.com SLVS349E - NOVEMBER 2001 - REVISED DECEMBER 2005 THERMAL INFORMATION The amount of heat that an LDO linear regulator generates is directly proportional to the amount of power it dissipates during operation. All integrated circuits have a maximum allowable junction temperature (TJmax) above which normal operation is not assured. A system designer must design the operating environment so that the operating junction temperature (TJ) does not exceed the maximum junction temperature (TJmax). The two main environmental variables that a designer can use to improve thermal performance are air flow and external heatsinks. The purpose of this information is to aid the designer in determining the proper operating environment for a linear regulator that is operating at a specific power level. In general, the maximum expected power (PDmax) consumed by a linear regulator is computed as shown in Equation 4: P D max + VIN(avg) * VOUT(avg) I OUT(avg) ) V I(avg) IQ (4) where: * VIN(avg) is the average input voltage * VOUT(avg) is the average output voltage * IOUT(avg) is the average output current * IQ is the quiescent current For most TI LDO regulators, the quiescent current is insignificant compared to the average output current; therefore, the term VIN(avg) x IQ can be neglected. The operating junction temperature is computed by adding the ambient temperature (TA) and the increase in temperature due to the regulator's power dissipation. The temperature rise is computed by multiplying the maximum expected power dissipation by the sum of the thermal resistances between the junction and the case (RJC), the case to heatsink (RCS), and the heatsink to ambient (RSA). Thermal resistances are measures of how effectively an object dissipates heat. Typically, the larger the device, the more surface area available for power dissipation and the lower the object's thermal resistance. Figure 24 illustrates these thermal resistances for a SOT223 package mounted in a JEDEC low-K board. 10 A TJ RJC CIRCUIT BOARD COPPER AREA C B B TC RCS A C RSA SOT223 Package TA Figure 24. Thermal Resistances Equation 5 summarizes the computation: RJC ) RCS ) RSA T J + T A ) PD max (5) The RJC is specific to each regulator as determined by its package, lead frame, and die size provided in the regulator's data sheet. The RSA is a function of the type and size of heatsink. For example, black body radiator type heatsinks can have RCS values ranging from 5C/W for very large heatsinks to 50C/W for very small heatsinks. The RCS is a function of how the package is attached to the heatsink. For example, if a thermal compound is used to attach a heatsink to a SOT223 package, RCS of 1C/W is reasonable. Even if no external black body radiator type heatsink is attached to the package, the board on which the regulator is mounted provides some heatsinking through the pin solder connections. Some packages, like the DDPAK and SOT223 packages, use a copper plane underneath the package or the circuit board ground plane for additional heatsinking to improve their thermal performance. Computer-aided thermal modeling can be used to compute very accurate approximations of an integrated circuit's thermal performance in different operating environments (for example, different types of circuit boards, different types and sizes of heatsinks, different air flows, etc.). Using these models, the three thermal resistances can be combined into one thermal resistance between junction and ambient (RJA). This RJA is valid only for the specific operating environment used in the computer model. Submit Documentation Feedback TPS794xx www.ti.com SLVS349E - NOVEMBER 2001 - REVISED DECEMBER 2005 Equation 5 simplifies into Equation 6: T J + T A ) PD max RJA (6) Rearranging Equation 6 gives Equation 7: T * TA R JA + J PD max (7) Using Equation 6 and the computer model generated curves shown in Figure 25, a designer can quickly compute the required heatsink thermal resistance/board area for a given ambient temperature, power dissipation, and operating environment. To illustrate, the TPS79425 in a SOT223 package was chosen. For this example, the average input voltage is 3.3 V, the output voltage is 2.5 V, the average output current is 1 A, the ambient temperature 55C, no air flow is present, and the operating environment is the same as documented below. Neglecting the quiescent current, the maximum average power is Equation 8: P D max + (3.3 * 2.5)V 1A + 800mW (8) 140 Substituting TJmax for TJ into Equation 4 gives Equation 9: R JA max + (125 * 55)C800mW + 87.5CW 120 (9) 100 From Figure 25, RJA vs PCB Copper Area, the ground plane needs to be 0.55 in2 for the part to dissipate 800 mW. The operating environment used to construct Figure 25 consisted of a board with 1 oz. copper planes. The package is soldered to a 1 oz. copper pad on the top of the board. The pad is tied through thermal vias to the 1 oz. ground plane. No Air Flow 160 80 60 40 20 0 0.1 1 10 PCB Copper Area (in2) Figure 25. SOT223 Thermal Resistance vs PCB Copper Area SOT223 POWER DISSIPATION The SOT223 package provides an effective means of managing power dissipation in surface-mount From the data in Figure 25 and rearranging equation 6, the maximum power dissipation for a different ground plane area and a specific ambient temperature can be computed, as shown in Figure 26. PD - Maximum Power Dissipation (W) RJA - Thermal Resistance (C/W) 180 applications. The SOT223 package dimensions are provided in the Mechanical Data section at the end of the data sheet. The addition of a copper plane directly underneath the SOT223 package enhances the thermal performance of the package. 6 TA = 25C 5 4 4 in2 PCB Area 3 0.5 in2 PCB Area 2 1 0 0 25 50 75 100 125 150 TA - Ambient Temperature (C) Figure 26. SOT223 Maximum Power Dissipation vs Ambient Temperature Submit Documentation Feedback 11 PACKAGE OPTION ADDENDUM www.ti.com 17-Aug-2012 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Drawing Pins Package Qty Eco Plan (2) Lead/ Ball Finish MSL Peak Temp (3) TPS79401DCQ ACTIVE SOT-223 DCQ 6 78 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS79401DCQG4 ACTIVE SOT-223 DCQ 6 78 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS79401DCQR ACTIVE SOT-223 DCQ 6 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS79401DCQRG4 ACTIVE SOT-223 DCQ 6 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS79401DGNR ACTIVE MSOPPowerPAD DGN 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79401DGNRG4 ACTIVE MSOPPowerPAD DGN 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79401DGNT ACTIVE MSOPPowerPAD DGN 8 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79401DGNTG4 ACTIVE MSOPPowerPAD DGN 8 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79418DCQ ACTIVE SOT-223 DCQ 6 78 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS79418DCQR ACTIVE SOT-223 DCQ 6 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS79418DGNR ACTIVE MSOPPowerPAD DGN 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79418DGNRG4 ACTIVE MSOPPowerPAD DGN 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79418DGNT ACTIVE MSOPPowerPAD DGN 8 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79418DGNTG4 ACTIVE MSOPPowerPAD DGN 8 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79425DCQ ACTIVE SOT-223 DCQ 6 78 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS79425DCQG4 ACTIVE SOT-223 DCQ 6 78 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS79425DCQR ACTIVE SOT-223 DCQ 6 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR Addendum-Page 1 Samples (Requires Login) PACKAGE OPTION ADDENDUM www.ti.com Orderable Device 17-Aug-2012 Status (1) Package Type Package Drawing Pins Package Qty Eco Plan (2) Lead/ Ball Finish MSL Peak Temp (3) TPS79425DCQRG4 ACTIVE SOT-223 DCQ 6 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS79425DGNR ACTIVE MSOPPowerPAD DGN 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79425DGNRG4 ACTIVE MSOPPowerPAD DGN 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79425DGNT ACTIVE MSOPPowerPAD DGN 8 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79425DGNTG4 ACTIVE MSOPPowerPAD DGN 8 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79428DCQ ACTIVE SOT-223 DCQ 6 78 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS79428DCQG4 ACTIVE SOT-223 DCQ 6 78 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS79428DCQR ACTIVE SOT-223 DCQ 6 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS79428DCQRG4 ACTIVE SOT-223 DCQ 6 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS79428DGNT ACTIVE MSOPPowerPAD DGN 8 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79428DGNTG4 ACTIVE MSOPPowerPAD DGN 8 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79430DCQ ACTIVE SOT-223 DCQ 6 78 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS79430DCQG4 ACTIVE SOT-223 DCQ 6 78 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS79430DCQR ACTIVE SOT-223 DCQ 6 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS79430DCQRG4 ACTIVE SOT-223 DCQ 6 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS79430DGNR ACTIVE MSOPPowerPAD DGN 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79430DGNRG4 ACTIVE MSOPPowerPAD DGN 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79430DGNT ACTIVE MSOPPowerPAD DGN 8 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM Addendum-Page 2 Samples (Requires Login) PACKAGE OPTION ADDENDUM www.ti.com Orderable Device 17-Aug-2012 Status (1) Package Type Package Drawing Pins Package Qty Eco Plan (2) Lead/ Ball Finish MSL Peak Temp (3) TPS79430DGNTG4 ACTIVE MSOPPowerPAD DGN 8 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79433DCQ ACTIVE SOT-223 DCQ 6 78 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS79433DCQR ACTIVE SOT-223 DCQ 6 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-2-260C-1 YEAR TPS79433DGNR ACTIVE MSOPPowerPAD DGN 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79433DGNRG4 ACTIVE MSOPPowerPAD DGN 8 2500 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79433DGNT ACTIVE MSOPPowerPAD DGN 8 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM TPS79433DGNTG4 ACTIVE MSOPPowerPAD DGN 8 250 Green (RoHS & no Sb/Br) CU NIPDAU Level-1-260C-UNLIM Samples (Requires Login) (1) The marketing status values are defined as follows: ACTIVE: Product device recommended for new designs. LIFEBUY: TI has announced that the device will be discontinued, and a lifetime-buy period is in effect. NRND: Not recommended for new designs. Device is in production to support existing customers, but TI does not recommend using this part in a new design. PREVIEW: Device has been announced but is not in production. Samples may or may not be available. OBSOLETE: TI has discontinued the production of the device. (2) Eco Plan - The planned eco-friendly classification: Pb-Free (RoHS), Pb-Free (RoHS Exempt), or Green (RoHS & no Sb/Br) - please check http://www.ti.com/productcontent for the latest availability information and additional product content details. TBD: The Pb-Free/Green conversion plan has not been defined. Pb-Free (RoHS): TI's terms "Lead-Free" or "Pb-Free" mean semiconductor products that are compatible with the current RoHS requirements for all 6 substances, including the requirement that lead not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, TI Pb-Free products are suitable for use in specified lead-free processes. Pb-Free (RoHS Exempt): This component has a RoHS exemption for either 1) lead-based flip-chip solder bumps used between the die and package, or 2) lead-based die adhesive used between the die and leadframe. The component is otherwise considered Pb-Free (RoHS compatible) as defined above. Green (RoHS & no Sb/Br): TI defines "Green" to mean Pb-Free (RoHS compatible), and free of Bromine (Br) and Antimony (Sb) based flame retardants (Br or Sb do not exceed 0.1% by weight in homogeneous material) (3) MSL, Peak Temp. -- The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. Important Information and Disclaimer:The information provided on this page represents TI's knowledge and belief as of the date that it is provided. TI bases its knowledge and belief on information provided by third parties, and makes no representation or warranty as to the accuracy of such information. Efforts are underway to better integrate information from third parties. TI has taken and continues to take reasonable steps to provide representative and accurate information but may not have conducted destructive testing or chemical analysis on incoming materials and chemicals. TI and TI suppliers consider certain information to be proprietary, and thus CAS numbers and other limited information may not be available for release. Addendum-Page 3 PACKAGE OPTION ADDENDUM www.ti.com 17-Aug-2012 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 4 PACKAGE MATERIALS INFORMATION www.ti.com 14-Jul-2012 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) TPS79401DCQR SOT-223 DCQ 6 2500 330.0 12.4 TPS79401DGNR MSOPPower PAD DGN 8 2500 330.0 TPS79401DGNT MSOPPower PAD DGN 8 250 TPS79418DCQR SOT-223 DCQ 6 TPS79418DGNR MSOPPower PAD DGN TPS79418DGNT MSOPPower PAD TPS79425DCQR TPS79425DGNR 6.8 7.3 1.88 8.0 12.0 Q3 12.4 5.3 3.4 1.4 8.0 12.0 Q1 180.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 2500 330.0 12.4 6.8 7.3 1.88 8.0 12.0 Q3 8 2500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 DGN 8 250 180.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 SOT-223 DCQ 6 2500 330.0 12.4 6.8 7.3 1.88 8.0 12.0 Q3 MSOPPower PAD DGN 8 2500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 TPS79425DGNT MSOPPower PAD DGN 8 250 180.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 TPS79428DCQR SOT-223 DCQ 6 2500 330.0 12.4 6.8 7.3 1.88 8.0 12.0 Q3 Pack Materials-Page 1 W Pin1 (mm) Quadrant PACKAGE MATERIALS INFORMATION www.ti.com 14-Jul-2012 Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant TPS79428DGNT MSOPPower PAD DGN 8 250 180.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 TPS79430DCQR SOT-223 DCQ 6 2500 330.0 12.4 6.8 7.3 1.88 8.0 12.0 Q3 TPS79430DGNR MSOPPower PAD DGN 8 2500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 TPS79430DGNT MSOPPower PAD DGN 8 250 180.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 TPS79433DCQR SOT-223 DCQ 6 2500 330.0 12.4 6.8 7.3 1.88 8.0 12.0 Q3 TPS79433DGNR MSOPPower PAD DGN 8 2500 330.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 TPS79433DGNT MSOPPower PAD DGN 8 250 180.0 12.4 5.3 3.4 1.4 8.0 12.0 Q1 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) TPS79401DCQR SOT-223 DCQ 6 2500 358.0 335.0 35.0 TPS79401DGNR MSOP-PowerPAD DGN 8 2500 367.0 367.0 35.0 TPS79401DGNT MSOP-PowerPAD DGN 8 250 210.0 185.0 35.0 Pack Materials-Page 2 PACKAGE MATERIALS INFORMATION www.ti.com 14-Jul-2012 Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) TPS79418DCQR SOT-223 DCQ 6 2500 358.0 335.0 35.0 TPS79418DGNR MSOP-PowerPAD DGN 8 2500 367.0 367.0 35.0 TPS79418DGNT MSOP-PowerPAD DGN 8 250 210.0 185.0 35.0 TPS79425DCQR SOT-223 DCQ 6 2500 358.0 335.0 35.0 TPS79425DGNR MSOP-PowerPAD DGN 8 2500 367.0 367.0 35.0 TPS79425DGNT MSOP-PowerPAD DGN 8 250 210.0 185.0 35.0 TPS79428DCQR SOT-223 DCQ 6 2500 358.0 335.0 35.0 TPS79428DGNT MSOP-PowerPAD DGN 8 250 210.0 185.0 35.0 TPS79430DCQR SOT-223 DCQ 6 2500 358.0 335.0 35.0 TPS79430DGNR MSOP-PowerPAD DGN 8 2500 367.0 367.0 35.0 TPS79430DGNT MSOP-PowerPAD DGN 8 250 210.0 185.0 35.0 TPS79433DCQR SOT-223 DCQ 6 2500 358.0 335.0 35.0 TPS79433DGNR MSOP-PowerPAD DGN 8 2500 367.0 367.0 35.0 TPS79433DGNT MSOP-PowerPAD DGN 8 250 210.0 185.0 35.0 Pack Materials-Page 3 IMPORTANT NOTICE Texas Instruments Incorporated and its subsidiaries (TI) reserve the right to make corrections, enhancements, improvements and other changes to its semiconductor products and services per JESD46C and to discontinue any product or service per JESD48B. Buyers should obtain the latest relevant information before placing orders and should verify that such information is current and complete. All semiconductor products (also referred to herein as "components") are sold subject to TI's terms and conditions of sale supplied at the time of order acknowledgment. TI warrants performance of its components to the specifications applicable at the time of sale, in accordance with the warranty in TI's terms and conditions of sale of semiconductor products. Testing and other quality control techniques are used to the extent TI deems necessary to support this warranty. Except where mandated by applicable law, testing of all parameters of each component is not necessarily performed. TI assumes no liability for applications assistance or the design of Buyers' products. Buyers are responsible for their products and applications using TI components. To minimize the risks associated with Buyers' products and applications, Buyers should provide adequate design and operating safeguards. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right relating to any combination, machine, or process in which TI components or services are used. Information published by TI regarding third-party products or services does not constitute a license 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 significant portions 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. TI is not responsible or liable for such altered documentation. Information of third parties may be subject to additional restrictions. Resale of TI components or services with statements different from or beyond the parameters stated by TI for that component or service voids all express and any implied warranties for the associated TI component or service and is an unfair and deceptive business practice. TI is not responsible or liable for any such statements. Buyer acknowledges and agrees that it is solely responsible for compliance with all legal, regulatory and safety-related requirements concerning its products, and any use of TI components in its applications, notwithstanding any applications-related information or support that may be provided by TI. Buyer represents and agrees that it has all the necessary expertise to create and implement safeguards which anticipate dangerous consequences of failures, monitor failures and their consequences, lessen the likelihood of failures that might cause harm and take appropriate remedial actions. Buyer will fully indemnify TI and its representatives against any damages arising out of the use of any TI components in safety-critical applications. In some cases, TI components may be promoted specifically to facilitate safety-related applications. With such components, TI's goal is to help enable customers to design and create their own end-product solutions that meet applicable functional safety standards and requirements. Nonetheless, such components are subject to these terms. No TI components are authorized for use in FDA Class III (or similar life-critical medical equipment) unless authorized officers of the parties have executed a special agreement specifically governing such use. Only those TI components which TI has specifically designated as military grade or "enhanced plastic" are designed and intended for use in military/aerospace applications or environments. Buyer acknowledges and agrees that any military or aerospace use of TI components which have not been so designated is solely at the Buyer's risk, and that Buyer is solely responsible for compliance with all legal and regulatory requirements in connection with such use. TI has specifically designated certain components which meet ISO/TS16949 requirements, mainly for automotive use. Components which have not been so designated are neither designed nor intended for automotive use; and TI will not be responsible for any failure of such components to meet such requirements. Products Applications Audio www.ti.com/audio Automotive and Transportation www.ti.com/automotive Amplifiers amplifier.ti.com Communications and Telecom www.ti.com/communications Data Converters dataconverter.ti.com Computers and Peripherals www.ti.com/computers DLP(R) Products www.dlp.com Consumer Electronics www.ti.com/consumer-apps DSP dsp.ti.com Energy and Lighting www.ti.com/energy Clocks and Timers www.ti.com/clocks Industrial www.ti.com/industrial Interface interface.ti.com Medical www.ti.com/medical Logic logic.ti.com Security www.ti.com/security Power Mgmt power.ti.com Space, Avionics and Defense www.ti.com/space-avionics-defense Microcontrollers microcontroller.ti.com Video and Imaging www.ti.com/video RFID www.ti-rfid.com OMAP Mobile Processors www.ti.com/omap TI E2E Community e2e.ti.com Wireless Connectivity www.ti.com/wirelessconnectivity Mailing Address: Texas Instruments, Post Office Box 655303, Dallas, Texas 75265 Copyright (c) 2012, Texas Instruments Incorporated