Product Folder Sample & Buy Support & Community Tools & Software Technical Documents Reference Design LP3878-ADJ SNVS311D - MAY 2005 - REVISED FEBRUARY 2015 LP3878-ADJ Micropower 800-mA Low-Noise "Ceramic Stable" Adjustable Voltage Regulator for 1-V to 5-V Applications 1 Features 3 Description * * * The LP3878-ADJ is an 800-mA, adjustable output, voltage regulator designed to provide high performance and low noise in applications requiring output voltages as low as 1 V. 1 * * * * * * Input Supply Voltage: 2.5 V to 16V Output Voltage Range: 1 V to 5.5 V Designed for Use With Low-ESR Ceramic Capacitors Very Low Output Noise 8-Lead SO PowerPADTM and WSON SurfaceMount Packages < 10-A Quiescent Current in Shutdown Low Ground Pin Current at all Loads Overtemperature and Overcurrent Protection -40C to 125C Operating Junction Temperature Range 2 Applications * * * * Using an optimized VIP (Vertically Integrated PNP) process, the LP3878-ADJ delivers superior performance: * Ground Pin Current: Typically 5.5 mA at 800-mA load, and 180 A at 100-A load. * Low Power Shutdown: The LP3878-ADJ draws less than 10-A quiescent current when the SHUTDOWN pin is pulled low. * Precision Output: Ensured output voltage accuracy is 1% at room temperature. * Low Noise: Broadband output noise is only 18 V (typical) with a 10-nF bypass capacitor. ASIC Power Supplies In: - Desktops, Notebooks, and Graphic Cards - Set Top Boxes, Printers, and Copiers DSP and FPGA Power Supplies SMPS Post-Regulator Medical Instrumentation Device Information(1) PART NUMBER PACKAGE LP3878-ADJ BODY SIZE (NOM) SO PowerPAD (8) 4.89 mm x 3.90 mm WSON (8) 4.00 mm x 4.00 mm (1) For all available packages, see the orderable addendum at the end of the data sheet. Basic Application Circuit VIN IN R1 LP3878-ADJ **S/D *4.7 F (Ceramic or Tantalum recommended) VOUT OUT S/D ADJ BYPASS *0.01 F CFF *10 F (Ceramic recommended) GND R2 *Capacitor values shown are minimum required to assure stability. A larger output capacitor provides improved dynamic response. Output capacitor must meet ESR requirements (see Application Information). **The SHUTDOWN (or S/D) pin must be actively terminated (see Device Functional Modes). Tie to IN (pin 4) if not used. 1 An IMPORTANT NOTICE at the end of this data sheet addresses availability, warranty, changes, use in safety-critical applications, intellectual property matters and other important disclaimers. PRODUCTION DATA. LP3878-ADJ SNVS311D - MAY 2005 - REVISED FEBRUARY 2015 www.ti.com Table of Contents 1 2 3 4 5 6 7 Features .................................................................. Applications ........................................................... Description ............................................................. Revision History..................................................... Pin Configuration and Functions ......................... Specifications......................................................... 1 1 1 2 3 4 6.1 6.2 6.3 6.4 6.5 6.6 4 4 4 4 5 6 Absolute Maximum Ratings ...................................... ESD Ratings.............................................................. Recommended Operating Conditions....................... Thermal Information .................................................. Electrical Characteristics........................................... Typical Characteristics .............................................. Detailed Description ............................................ 11 7.1 Overview ................................................................. 11 7.2 Functional Block Diagram ....................................... 11 7.3 Feature Description................................................. 11 7.4 Device Functional Modes........................................ 12 8 Application and Implementation ........................ 13 8.1 Application Information............................................ 13 8.2 Typical Application ................................................. 13 9 Power Supply Recommendations...................... 17 10 Layout................................................................... 17 10.1 Layout Guidelines ................................................. 17 10.2 Layout Example .................................................... 17 10.3 Power Dissipation ................................................. 17 11 Device and Documentation Support ................. 18 11.1 11.2 11.3 11.4 Documentation Support ........................................ Trademarks ........................................................... Electrostatic Discharge Caution ............................ Glossary ................................................................ 18 18 18 18 12 Mechanical, Packaging, and Orderable Information ........................................................... 18 4 Revision History NOTE: Page numbers for previous revisions may differ from page numbers in the current version. Changes from Revision C (December 2014) to Revision D Page * Deleted trademark symbol from VIP - no longer trademark; add reference design icon to Top Navigators.......................... 1 * Deleted soldering info - now in POA ..................................................................................................................................... 4 * Changed wording of footnote 5 to Ab Max Ratings ............................................................................................................... 4 * Changed IOUT to IOUT throughout document............................................................................................................................ 5 * Changed wording of Reverse Input-Output Voltage ............................................................................................................ 11 * Changed outpin pin to OUT pin ........................................................................................................................................... 15 * Added new paragraph to Noise Bypass Capacitor subsection ........................................................................................... 15 Changes from Revision B (April 2013) to Revision C * Added Pin Configuration and Functions section, ESD Ratings table, Feature Description section, Device Functional Modes, Application and Implementation section, Power Supply Recommendations section, Layout section, Device and Documentation Support section, and Mechanical, Packaging, and Orderable Information section; update thermal values ....................................................................................................................................................................... 1 Changes from Revision A (April 2013) to Revision B * 2 Page Page Changed layout of National Data Sheet to TI format ........................................................................................................... 16 Submit Documentation Feedback Copyright (c) 2005-2015, Texas Instruments Incorporated Product Folder Links: LP3878-ADJ LP3878-ADJ www.ti.com SNVS311D - MAY 2005 - REVISED FEBRUARY 2015 5 Pin Configuration and Functions SO PowerPAD (DDA) Package 8-Pin Top View BYPASS 1 8 SHUTDOWN N/C 2 7 N/C Thermal Pad GROUND 3 6 ADJ IN 4 5 OUT BYPASS 1 N/C 2 GROUND 3 IN 4 Thermal Pad WSON (NGT) Package 8-Pin Top View 8 SHUTDOWN 7 N/C 6 ADJ 5 OUT Pin Functions PIN NAME NUMBER I/O DESCRIPTION ADJ 6 I Provides feedback to error amplifier from the resistive divider that sets the output voltage. BYPASS 1 -- The capacitor connected between BYPASS and GROUND lowers output noise voltage level and is required for loop stability. GROUND 3 -- Device ground. IN 4 I Input source voltage. N/C 2 DO NOT CONNECT. Device pin 2 is reserved for post packaging test and calibration of the LP3878-ADJ VADJ accuracy. This pin must be left floating. Do not connect to any potential. Do not connect to ground. Any attempt to do pin continuity testing on device pin 2 is discouraged. Continuity test results will be variable depending on the actions of the factory calibration. Aggressive pin continuity testing (high voltage, or high current) on device pin 2 may activate the trim circuitry forcing VADJ to move out of tolerance. N/C 7 No internal connection. OUT 5 O Regulated output voltage. SHUTDOWN 8 I Output is enabled above turnon threshold voltage. Pull down to turn off regulator output. Thermal Pad -- -- The exposed thermal pad on the bottom of the package should be connected to a copper thermal pad on the PCB under the package. The use of thermal vias to remove heat from the package into the PCB is recommended. Connect the thermal pad to ground potential or leave floating. Do not connect the thermal pad to any potential other than the same ground potential seen at device pin 3. For additional information on using TI's Non Pull Back WSON package, see Application Note AN-1187, SNOA401. Submit Documentation Feedback Copyright (c) 2005-2015, Texas Instruments Incorporated Product Folder Links: LP3878-ADJ 3 LP3878-ADJ SNVS311D - MAY 2005 - REVISED FEBRUARY 2015 www.ti.com 6 Specifications 6.1 Absolute Maximum Ratings over operating free-air temperature range (unless otherwise noted) (1) (2) MIN SHUTDOWN pin Power dissipation (3) MAX UNIT 1 kV Internally Limited Input supply voltage (survival), VIN -0.3 16 V ADJ pin -0.3 6 V -0.3 6 V Output voltage (survival), VOUT (4) IOUT (survival) Short-Circuit Protected Input - output voltage (survival), VIN - VOUT (5) -0.3 16 V Storage temperature, Tstg -65 150 C (1) (2) (3) (4) (5) Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. These are stress ratings only, which do not imply functional operation of the device at these or any other conditions beyond those indicated under Recommended Operating Conditions. Exposure to absolute-maximum-rated conditions for extended periods may affect device reliability. If Military- or Aerospace-specified devices are required, please contact the TI Sales Office/Distributors for availability and specifications. The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(MAX), the junction-to-ambient thermal resistance, RJA, and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature is calculated using: P(MAX) = (TJ(MAX) - TA) / RJA. The value of RJA for the WSON (NGT) and SO PowerPAD (DDA) packages are specifically dependent on PCB trace area, trace material, and the number of layers and thermal vias. For improved thermal resistance and power dissipation for the WSON package, see Application Note AN-1187, SNOA401. Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. If used in a dual-supply system where the regulator load is returned to a negative supply, the LP3878-ADJ output must be diodeclamped to ground. The PNP pass element contains a parasitic diode between the IN pin and the OUT pin that is normally reverse-biased. Forcing the OUT pin voltage above the IN pin voltage will turn on this diode and may induce a latch-up mode which can damage the part (see Application and Implementation). 6.2 ESD Ratings V(ESD) (1) Electrostatic discharge Human body model (HBM), per ANSI/ESDA/JEDEC JS-001, all pins (1) VALUE UNIT 2000 V JEDEC document JEP155 states that 500-V HBM allows safe manufacturing with a standard ESD control process. 6.3 Recommended Operating Conditions over operating free-air temperature range (unless otherwise noted) MIN MAX 2.5 16 UNIT VIN Supply input voltage VSD SHUTDOWN input voltage VIN V IOUT Output current 800 mA TJ Operating junction temperature 125 C -40 V 6.4 Thermal Information LP3878-ADJ THERMAL METRIC (1) DDA NGT UNIT 8 PINS RJA Junction-to-ambient thermal resistance 42.5 38.1 RJC(top) Junction-to-case (top) thermal resistance 54.0 27.9 RJB Junction-to-board thermal resistance 26.5 15.2 JT Junction-to-top characterization parameter 8.0 0.2 JB Junction-to-board characterization parameter 26.4 15.3 RJC(bot) Junction-to-case (bottom) thermal resistance 3.6 4.5 (1) 4 C/W For more information about traditional and new thermal metrics, see the IC Package Thermal Metrics application report, SPRA953. Submit Documentation Feedback Copyright (c) 2005-2015, Texas Instruments Incorporated Product Folder Links: LP3878-ADJ LP3878-ADJ www.ti.com SNVS311D - MAY 2005 - REVISED FEBRUARY 2015 6.5 Electrical Characteristics Limits are specified through design, testing, or correlation. The limits are used to calculate TI's Average Outgoing Quality Level (AOQL). Unless otherwise specified: TJ = 25C, VIN = 3 V, VOUT = 1 V, IOUT = 1 mA, COUT = 10 F, CIN = 4.7 F, VSD = 2 VVSD, CBYPASS = 10 nF. PARAMETER VADJ VOUT/VIN TEST CONDITIONS Adjust pin voltage Output voltage line regulation MIN TYP MAX 0.99 1.00 1.01 1 mA IOUT 800 mA, 3 V VIN 6 V 0.98 1.00 1.02 1 mA IOUT 800 mA, 3 V VIN 6 V -40C TJ 125C 0.97 3 V VIN 16 V 0.007 VIN(MIN) 3.1 IOUT = 800 mA, VOUT VOUT(NOM) - 1% 0 TJ 125C 2.5 V IOUT = 800 mA, VOUT VOUT(NOM) - 1% 0 TJ 125C, -40C TJ 125C 2.8 2.5 IOUT = 750 mA, VOUT VOUT(NOM) - 1% -40C TJ 125C 3.0 IOUT = 100 A 1 2 150 200 IOUT = 100 A, -40C TJ 125C VDOUT Dropout voltage VOUT = 3.8 V 3 IOUT = 200 mA IOUT = 200 mA, -40C TJ 125C 475 IOUT = 800 mA, -40C TJ 125C 600 1100 IOUT = 100 A 180 IOUT = 100 A, -40C TJ 125C Ground pin current mV 300 IOUT = 800 mA IGND %/V 2.5 IOUT = 750 mA, VOUT VOUT(NOM) - 1% (1) 0.014 0.032 IOUT = 800 mA, VOUT VOUT(NOM) - 1% -40C TJ 125C Minimum input voltage required to maintain output regulation V 1.03 3 V VIN 16 V, -40C TJ 125C IOUT = 800 mA, VOUT VOUT(NOM) - 1% UNIT 200 A 225 IOUT = 200 mA 1.5 IOUT = 200 mA, -40C TJ 125C 2 3.5 IOUT = 800 mA 5.5 IOUT = 800 mA, -40C TJ 125C mA 8.5 15 IOUT(PK) Peak output current VOUT VOUT(NOM) - 5% 1200 IOUT(MAX) Short-circuit current RL = 0 (steady state) 1300 en Output noise voltage (RMS) Bandwidth = 100 Hz to 100 kHz, CBYPASS = 10 nF 18 V(RMS) VOUT/VIN Ripple rejection f = 1 kHz 60 dB IADJ ADJ pin bias current (sourcing) IOUT = 800 mA 200 nA VH = Output ON 1.4 mA SHUTDOWN Input VH = Output ON, -40C TJ 125C VSD SHUTDOWN input voltage 1.6 VL = Output OFF, IIN 10 A VL = Output OFF, IIN 10 A -40C TJ 125C 0.20 VOUT 10 mV, IIN 50 A 0.6 VSD = 0 V ISD SHUTDOWN input current 0.02 VSD = 0 V, -40C TJ 125C -1 VSD = 5 V 5 VSD = 5 V, -40C TJ 125C (1) V 0.04 A 15 Dropout voltage specification applies only if VIN is sufficient so that it does not limit regulator operation. Submit Documentation Feedback Copyright (c) 2005-2015, Texas Instruments Incorporated Product Folder Links: LP3878-ADJ 5 LP3878-ADJ SNVS311D - MAY 2005 - REVISED FEBRUARY 2015 www.ti.com 6.6 Typical Characteristics Unless otherwise specified: VIN = 3.3 V, VOUT = 1 V, IOUT = 1 mA, CIN = 4.7 F, COUT = 10 F, VSD = 2 V, CBYP = 10 nF, TJ = 25C. 10.0 9.0 8.0 IGND (mA) 7.0 IL = 800 mA 6.0 5.0 4.0 3.0 IL = 240 mA 2.0 1.0 IL = 1 mA 0 -60 -40 -20 0 20 40 60 80 100 120 140 TEMPERATURE (C) Figure 2. Minimum VIN Over Temperature Figure 1. IGND vs Temperature 1.020 1.015 VOUT (V) 1.010 1.005 1.000 0.995 0.990 0.985 0.980 -50 -25 0 25 50 75 100 125 o TEMPERATURE ( C) Figure 3. IGND vs ILoad Figure 4. VOUT vs Temperature 4.5 4.0 TJ = 125oC TJ = 0C 4.0 3.5 IL = 800 mA 400 mA IL = 400 mA 3.5 800 mA VIN (V) VIN (V) 3.0 2.5 3.0 2.5 2.0 2.0 100 mA IL = 100 mA 1.5 1.0 1.0 1,5 1.5 2.0 2.5 3.0 3.5 1.0 1.0 2.0 2.5 3.0 3.5 VOUT (V) VOUT (V) Figure 5. Minimum VIN vs VOUT 6 1.5 Submit Documentation Feedback Figure 6. Minimum VIN vs VOUT Copyright (c) 2005-2015, Texas Instruments Incorporated Product Folder Links: LP3878-ADJ LP3878-ADJ www.ti.com SNVS311D - MAY 2005 - REVISED FEBRUARY 2015 Typical Characteristics (continued) Unless otherwise specified: VIN = 3.3 V, VOUT = 1 V, IOUT = 1 mA, CIN = 4.7 F, COUT = 10 F, VSD = 2 V, CBYP = 10 nF, TJ = 25C. 4.0 100 TJ = -40C 90 IL = 400 mA 3.5 80 RIPPLE REJECTION (dB) IL = 800 mA VIN (V) 3.0 2.5 2.0 IL = 100 mA 70 60 50 40 30 20 1.5 10 1.0 1.0 1.5 2.0 2.5 3.0 3.5 0 10 VOUT (V) 100 1k 10k 100k 1M FREQUENCY (Hz) Figure 7. Minimum VIN vs VOUT Figure 8. Ripple Rejection 100 90 IL= 800 mA RIPPLE REJECTION (dB) 80 70 60 50 40 30 20 10 0 10 100 1k 10k 100k 1M FREQUENCY (Hz) Figure 9. Ripple Rejection Figure 10. Output Noise Spectral Density Figure 11. Output Noise Spectral Density Figure 12. Line Transient Response Submit Documentation Feedback Copyright (c) 2005-2015, Texas Instruments Incorporated Product Folder Links: LP3878-ADJ 7 LP3878-ADJ SNVS311D - MAY 2005 - REVISED FEBRUARY 2015 www.ti.com Typical Characteristics (continued) Unless otherwise specified: VIN = 3.3 V, VOUT = 1 V, IOUT = 1 mA, CIN = 4.7 F, COUT = 10 F, VSD = 2 V, CBYP = 10 nF, TJ = 25C. 8 Figure 13. Line Transient Response Figure 14. Line Transient Response Figure 15. Line Transient Response Figure 16. Line Transient Response Figure 17. Line Transient Response Figure 18. Line Transient Response Submit Documentation Feedback Copyright (c) 2005-2015, Texas Instruments Incorporated Product Folder Links: LP3878-ADJ LP3878-ADJ www.ti.com SNVS311D - MAY 2005 - REVISED FEBRUARY 2015 Typical Characteristics (continued) Unless otherwise specified: VIN = 3.3 V, VOUT = 1 V, IOUT = 1 mA, CIN = 4.7 F, COUT = 10 F, VSD = 2 V, CBYP = 10 nF, TJ = 25C. Figure 19. Line Transient Response Figure 20. Line Transient Response Figure 21. Line Transient Response Figure 22. Line Transient Response Figure 23. Load Transient Response Figure 24. Load Transient Response Submit Documentation Feedback Copyright (c) 2005-2015, Texas Instruments Incorporated Product Folder Links: LP3878-ADJ 9 LP3878-ADJ SNVS311D - MAY 2005 - REVISED FEBRUARY 2015 www.ti.com Typical Characteristics (continued) Unless otherwise specified: VIN = 3.3 V, VOUT = 1 V, IOUT = 1 mA, CIN = 4.7 F, COUT = 10 F, VSD = 2 V, CBYP = 10 nF, TJ = 25C. 1.2 1.2 1 1 0.6 0.8 VOUT (V) VOUT (V) 25oC 0o C 0.8 25oC 0.4 0.6 0.4 125oC 0.2 0o C 0.2 0 0 0 0.5 1 1.5 2 0 0.5 1 1.5 2 VS/D VS/D Figure 25. Turnon Characteristics 10 125oC Submit Documentation Feedback Figure 26. Turnoff Characteristics Copyright (c) 2005-2015, Texas Instruments Incorporated Product Folder Links: LP3878-ADJ LP3878-ADJ www.ti.com SNVS311D - MAY 2005 - REVISED FEBRUARY 2015 7 Detailed Description 7.1 Overview The LP3878-ADJ is an adjustable regulator; the output voltage can be set from 1 V to 5.5 V. The device can deliver 800-mA continuous load current. Standard regulator features, such as overcurrent and overtemperature protection, are also included. The LP3878-ADJ contains other features: * Low power shutdown current and low ground pin current * Very low output noise * 8-lead SO PowerPAD or WSON surface-mount packages to allow for increased power dissipation. 7.2 Functional Block Diagram ADJ 6 BYPASS 1 IN 4 OUT 5 Error Amp 2 N/C + 8 SHUTDOWN + 1V VREF LP3878ADJ 7 N/C GROUND 3 7.3 Feature Description 7.3.1 Shutdown Input Operation The LP3878-ADJ is shut off by pulling the SHUTDOWN input low, and turned on by pulling it high. If this feature is not to be used, the SHUTDOWN input should be tied to VIN to keep the regulator output on at all times. To assure proper operation, the signal source used to drive the SHUTDOWN input must be able to swing above and below the specified turnon or turnoff voltage thresholds listed in the Electrical Characteristics under VON/OFF. 7.3.2 Reverse Input-Output Voltage The PNP power transistor used as the pass element in the LP3878-ADJ contains a parasitic diode between the IN pin and the OUT pin. During normal operation (where the IN pin voltage is higher than the OUT pin voltage) this parasitic diode is reverse-biased. However, if the OUT pin voltage is pulled above the IN pin voltage this diode will turn ON, and current will flow into the LP3878-ADJ OUT pin. In such cases, a parasitic SCR between the IN pin and the GND pin can latch ON which will allow a high current to flow from the VIN supply, into the IN pin to ground, which can damage the part. In any application where the OUT pin voltage may be higher than the IN pin voltage, even momentarily, an external Schottky diode must be connected from the IN pin to the OUT pin (cathode to IN pin, anode to OUT pin), to limit the reverse voltage across the LP3878-ADJ to 0.3 V (see Absolute Maximum Ratings). 7.3.3 Low Output Noise With a 10-nF capacitor on the BYPASS pin, the output noise is only 18 V. Submit Documentation Feedback Copyright (c) 2005-2015, Texas Instruments Incorporated Product Folder Links: LP3878-ADJ 11 LP3878-ADJ SNVS311D - MAY 2005 - REVISED FEBRUARY 2015 www.ti.com 7.4 Device Functional Modes 7.4.1 Operation With VOUT(TARGET) + 2 V VIN 16 V The device operates if the input voltage is equal to, or exceeds VOUT(TARGET) + 2 V. At input voltages below the minimum VIN requirement, the device does not operate correctly and output voltage may not reach target value. 7.4.2 Operation With SHUTDOWN Pin Control LP3878-ADJ is turned off by pulling the SHUTDOWN pin low, and turned on by pulling it high. If this feature is not used, the SHUTDOWN pin should be tied to VIN to keep the regulator output on at all times. To assure proper operation, the signal source used to drive the SHUTDOWN input must be able to swing above and below the specified turnon and turnoff voltage thresholds listed in the Electrical Characteristics under VL and VH. 12 Submit Documentation Feedback Copyright (c) 2005-2015, Texas Instruments Incorporated Product Folder Links: LP3878-ADJ LP3878-ADJ www.ti.com SNVS311D - MAY 2005 - REVISED FEBRUARY 2015 8 Application and Implementation NOTE Information in the following applications sections is not part of the TI component specification, and TI does not warrant its accuracy or completeness. TI's customers are responsible for determining suitability of components for their purposes. Customers should validate and test their design implementation to confirm system functionality. 8.1 Application Information The LP3878-ADJ can provide 800-mA output current with 2.5-V to 6-V output voltage. A minimum 10-F output capacitor is required for loop stability. An input capacitor of at least 4.7-F is required also. The SHUTDOWN pin must be tied to input if not used. A 10-nF bypass capacitor is required to improve loop stability, it also can reduce noise on the regulator output significantly. A capacitor, CFF, is required to increase phase margin and assure loop stability. Output voltage can be set by two resistors R1 and R2 (see Figure 27), and R2 must be less than 5 k to ensure loop stability. 8.2 Typical Application VIN IN VOUT OUT R1 LP3878-ADJ S/D **S/D ADJ BYPASS *4.7 F (Ceramic or Tantalum recommended) CFF *10 F (Ceramic recommended) GND R2 *0.01 F *Capacitor values shown are minimum required to assure stability. Larger output capacitor provides improved dynamic response. Output capacitor must meet ESR requirements (see Application Information). **The SHUTDOWN (or S/D) pin must be actively terminated (see Device Functional Modes). Tie to IN (pin 4) if not used. Figure 27. Basic Application Circuit 8.2.1 Design Requirements DESIGN PARAMETER VALUE Input voltage 3.8 V 10% Output voltage 1.8 V 3% Output current 800 mA (maximum) Input capacitor 4.7 F (minimum) Output capacitor 10 F (minimum) Bypass capacitor 10 nF External resistor R2 1 k (less than 5 k) Submit Documentation Feedback Copyright (c) 2005-2015, Texas Instruments Incorporated Product Folder Links: LP3878-ADJ 13 LP3878-ADJ SNVS311D - MAY 2005 - REVISED FEBRUARY 2015 www.ti.com 8.2.2 Detailed Design Procedure 8.2.2.1 External Capacitors Like any low-dropout regulator, the LP3878-ADJ requires external capacitors for regulator stability. These capacitors must be correctly selected for good performance. 8.2.2.1.1 Input Capacitor A capacitor whose value is at least 4.7 F (20%) is required between the LP3878-ADJ input and ground. A good quality X5R or X7R ceramic capacitor should be used. Capacitor tolerance and temperature variation must be considered when selecting a capacitor (see Capacitor Characteristics) to assure the minimum requirement of input capacitance is met over all operating conditions. The input capacitor must be located not more than 0.5 inches from the input pin and returned to a clean analog ground. Any good quality ceramic or tantalum capacitor may be used, assuming the minimum input capacitance requirement is met. 8.2.2.1.2 Output Capacitor The LP3878-ADJ requires a ceramic output capacitor whose size is at least 10 F (20%). A good quality X5R or X7R ceramic capacitor should be used. Capacitance tolerance and temperature characteristics must be considered when selecting an output capacitor. The LP3878-ADJ is designed specifically to work with ceramic output capacitors, utilizing circuitry which allows the regulator to be stable across the entire range of output current with an ultra-low equivalent series resistance (ESR) output capacitor. The output capacitor selected must meet the requirement for minimum amount of capacitance and also have an ESR value which is within the stable range. A curve is provided which shows the stable ESR range as a function of load current (see Figure 28). 10 ESR (:) 1 0.1 STABLE REGION 0.01 0.001 0 200 400 600 800 LOAD CURRENT (mA) Figure 28. Stable Region for Output Capacitor ESR 14 Submit Documentation Feedback Copyright (c) 2005-2015, Texas Instruments Incorporated Product Folder Links: LP3878-ADJ LP3878-ADJ www.ti.com SNVS311D - MAY 2005 - REVISED FEBRUARY 2015 NOTE Important: The output capacitor must maintain its ESR within the stable region over the full operating temperature range of the application to assure stability. The output capacitor ESR forms a zero which is required to add phase lead near the loop gain crossover frequency, typically in the range of 50 kHz to 200 kHz. The ESR at lower frequencies is of no importance. Some capacitor manufacturers list ESR at low frequencies only, and some give a formula for Dissipation Factor (DF) which can be used to calculate a value for a term referred to as ESR. However, because the DF formula is usually at a much lower frequency than the range listed above, it will give an unrealistically high value. If good quality X5R or X7R ceramic capacitors are used, the actual ESR in the 50-kHz to 200-kHz range will not exceed 25 m. If these are used as output capacitors for the LP3878-ADJ, the regulator stability requirements are satisfied. It is important to remember that capacitor tolerance and variation with temperature must be taken into consideration when selecting an output capacitor so that the minimum required amount of output capacitance is provided over the full operating temperature range (see Capacitor Characteristics). The output capacitor must be located not more than 0.5 inches from the OUT pin and returned to a clean analog ground. 8.2.2.1.3 Noise Bypass Capacitor The 10-nF capacitor on the BYPASS pin significantly reduces noise on the regulator output and is required for loop stability. However, the capacitor is connected directly to a high-impedance circuit in the bandgap reference. Because this circuit has only a few A flowing in it, any significant loading on this node will cause a change in the regulated output voltage. For this reason, dc leakage current through the noise bypass capacitor must never exceed 100 nA, and should be kept as low as possible for best output voltage accuracy. The types of capacitors best suited for the noise bypass capacitor are ceramic and film. High-quality ceramic capacitors with either NPO or COG dielectric typically have very low leakage. 10-nF polypropylene and polycarbonate film capacitors are available in small surface-mount packages and typically have extremely low leakage current. While the capacitor value on the BYPASS will affect start-up time, this is not intended to be used as a soft-start circuit. There is no dedicated discharge circuitry for this capacitor, and it can be pre-biased if the IN pin, or the SHUTDOWN pin are not at 0 V at start-up. 8.2.2.2 Feedforward Capacitor The feedforward capacitor designated CFF in Figure 27 is required to increase phase margin and assure loop stability. Improved phase margin also gives better transient response to changes in load or input voltage, and faster settling time on the output voltage when transients occur. CFF forms both a pole and zero in the loop gain, the zero providing beneficial phase lead (which increases phase margin) and the pole adding undesirable phase lag (which should be minimized). The zero frequency is determined both by the value of CFF and R1: fZ = 1 / (2CFF x R1) (1) The pole frequency resulting from CFF is determined by the value of CFF and the parallel combination of R1 and R2: fP = 1 / (2CFF x (R1 // R2)) (2) At higher output voltages where R1 is much greater than R2, the value of R2 primarily determines the value of the parallel combination of R1 // R2. This puts the pole at a much higher frequency than the zero. As the regulated output voltage is reduced (and the value of R1 decreases), the parallel effect of R2 diminishes and the two equations become equal (at which point the pole and zero cancel out). Because the pole frequency gets closer to the zero at lower output voltages, the beneficial effects of CFF are increased if the frequency range of the zero is shifted slightly higher for applications with low VOUT (because then the pole adds less phase lag at the loop crossover frequency). CFF should be selected to place the pole-zero pair at a frequency where the net phase lead added to the loop at the crossover frequency is maximized. The following design guidelines were obtained from bench testing to optimize phase margin, transient response, and settling time: * For VOUT 2.5 V: CFF should be selected to set the zero frequency in the range of about 50 kHz to 200 kHz. Submit Documentation Feedback Copyright (c) 2005-2015, Texas Instruments Incorporated Product Folder Links: LP3878-ADJ 15 LP3878-ADJ SNVS311D - MAY 2005 - REVISED FEBRUARY 2015 * www.ti.com For VOUT > 2.5 V: CFF should be selected to set the zero frequency in the range of about 20 kHz to 100 kHz. 8.2.2.3 Capacitor Characteristics 8.2.2.3.1 Ceramic The LP3878-ADJ was designed to work with ceramic capacitors on the output to take advantage of the benefits they offer: for capacitance values in the 10-F range, ceramics are the least expensive and also have the lowest ESR values (which makes them best for eliminating high-frequency noise). The ESR of a typical 10-F ceramic capacitor is in the range of 5 m to 10 m, which meets the ESR limits required for stability by the LP3878-ADJ. One disadvantage of ceramic capacitors is that their capacitance can vary with temperature. Many large value ceramic capacitors ( 2.2 F) are manufactured with the Z5U or Y5V temperature characteristic, which results in the capacitance dropping by more than 50% as the temperature goes from 25C to 85C. Another significant problem with Z5U and Y5V dielectric devices is that the capacitance drops severely with applied voltage. A typical Z5U or Y5V capacitor can lose 60% of its rated capacitance with half of the rated voltage applied to it. For these reasons, X7R and X5R type ceramic capacitors must be used on the input and output of the LP3878ADJ. 8.2.2.4 Setting the Output Voltage The output voltage is set using resistors R1 and R2 (see Figure 27). The formula for output voltage is: VOUT = VADJ x (1 + (R1 / R2)) (3) R2 must be less than 5 k to ensure loop stability. To prevent voltage errors, R1 and R2 must be located near the LP3878-ADJ and connected via traces with no other currents flowing in them (Kelvin connect). The bottom of the R1/R2 divider must be connected directly to the LP3878-ADJ ground pin. 8.2.3 Application Curves Figure 29. Load Transient Response 16 Submit Documentation Feedback Figure 30. Load Transient Response Copyright (c) 2005-2015, Texas Instruments Incorporated Product Folder Links: LP3878-ADJ LP3878-ADJ www.ti.com SNVS311D - MAY 2005 - REVISED FEBRUARY 2015 9 Power Supply Recommendations The LP3878-ADJ is designed to operate from an input voltage supply range between 2.5 V and 16 V. The input voltage range provides adequate headroom in order for the device to have a regulated output. This input supply must be well regulated. An input capacitor of at least 4.7 F is required. 10 Layout 10.1 Layout Guidelines Good PC layout practices must be used or instability can be induced because of ground loops and voltage drops. The input and output capacitors must be directly connected to the input, output, and ground pins of the regulator using traces which do not have other currents flowing in them (Kelvin connect). The best way to do this is to lay out CIN and COUT near the device with short traces to the IN, OUT, and ground pins. The regulator ground pin should be connected to the external circuit ground so that the regulator and its capacitors have a single point ground. It should be noted that stability problems have been seen in applications where vias to an internal ground plane were used at the ground points of the IC and the input and output capacitors. This was caused by varying ground potentials at these nodes resulting from current flowing through the ground plane. Using a single-point ground technique for the regulator and its capacitors fixed the problem. Because high current flows through the traces going into IN and coming from OUT, Kelvin connect the capacitor leads to these pins so there is no voltage drop in series with the input and output capacitors. 10.2 Layout Example BYP S/D N/C N/C Bypass Capacitor R2 CFF GND ADJ IN OUT Input Capacitor R1 Output Capacitor 10.3 Power Dissipation The LP3878-ADJ is offered in the 8-lead SO PowerPAD or WSON surface-mount packages to allow for increased power dissipation compared to the SO-8 and Mini SO-8. For details on thermal performance as well as mounting and soldering specifications, refer to Application Note AN-1187, SNOA401. Submit Documentation Feedback Copyright (c) 2005-2015, Texas Instruments Incorporated Product Folder Links: LP3878-ADJ 17 LP3878-ADJ SNVS311D - MAY 2005 - REVISED FEBRUARY 2015 www.ti.com 11 Device and Documentation Support 11.1 Documentation Support 11.1.1 Related Documentation For related documentation see the following: Application Note AN-1187, SNOA401 11.2 Trademarks PowerPAD is a trademark of Texas Instruments. 11.3 Electrostatic Discharge Caution These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam during storage or handling to prevent electrostatic damage to the MOS gates. 11.4 Glossary SLYZ022 -- TI Glossary. This glossary lists and explains terms, acronyms, and definitions. 12 Mechanical, Packaging, and Orderable Information The following pages include mechanical, packaging, and orderable information. This information is the most current data available for the designated devices. This data is subject to change without notice and revision of this document. For browser-based versions of this data sheet, refer to the left-hand navigation. 18 Submit Documentation Feedback Copyright (c) 2005-2015, Texas Instruments Incorporated Product Folder Links: LP3878-ADJ PACKAGE OPTION ADDENDUM www.ti.com 11-Jan-2021 PACKAGING INFORMATION Orderable Device Status (1) Package Type Package Pins Package Drawing Qty Eco Plan (2) Lead finish/ Ball material MSL Peak Temp Op Temp (C) Device Marking (3) (4/5) (6) LP3878MR-ADJ NRND SO PowerPAD DDA 8 95 Non-RoHS & Green Call TI Call TI -40 to 125 3878 MRADJ LP3878MR-ADJ/NOPB ACTIVE SO PowerPAD DDA 8 95 RoHS & Green SN Level-3-260C-168 HR -40 to 125 3878 MRADJ LP3878MRX-ADJ/NOPB ACTIVE SO PowerPAD DDA 8 2500 RoHS & Green SN Level-3-260C-168 HR -40 to 125 3878 MRADJ LP3878SD-ADJ/NOPB ACTIVE WSON NGT 8 1000 RoHS & Green NIPDAU | SN Level-1-260C-UNLIM -40 to 125 3878ADJ LP3878SDX-ADJ/NOPB ACTIVE WSON NGT 8 4500 RoHS & Green NIPDAU | SN Level-1-260C-UNLIM -40 to 125 3878ADJ (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) RoHS: TI defines "RoHS" to mean semiconductor products that are compliant with the current EU RoHS requirements for all 10 RoHS substances, including the requirement that RoHS substance do not exceed 0.1% by weight in homogeneous materials. Where designed to be soldered at high temperatures, "RoHS" products are suitable for use in specified lead-free processes. TI may reference these types of products as "Pb-Free". RoHS Exempt: TI defines "RoHS Exempt" to mean products that contain lead but are compliant with EU RoHS pursuant to a specific EU RoHS exemption. Green: TI defines "Green" to mean the content of Chlorine (Cl) and Bromine (Br) based flame retardants meet JS709B low halogen requirements of <=1000ppm threshold. Antimony trioxide based flame retardants must also meet the <=1000ppm threshold requirement. (3) MSL, Peak Temp. - The Moisture Sensitivity Level rating according to the JEDEC industry standard classifications, and peak solder temperature. (4) There may be additional marking, which relates to the logo, the lot trace code information, or the environmental category on the device. (5) Multiple Device Markings will be inside parentheses. Only one Device Marking contained in parentheses and separated by a "~" will appear on a device. If a line is indented then it is a continuation of the previous line and the two combined represent the entire Device Marking for that device. (6) Lead finish/Ball material - Orderable Devices may have multiple material finish options. Finish options are separated by a vertical ruled line. Lead finish/Ball material values may wrap to two lines if the finish value exceeds the maximum column width. Addendum-Page 1 Samples PACKAGE OPTION ADDENDUM www.ti.com 11-Jan-2021 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 2 PACKAGE MATERIALS INFORMATION www.ti.com 5-Jan-2021 TAPE AND REEL INFORMATION *All dimensions are nominal Device Package Package Pins Type Drawing SPQ Reel Reel A0 Diameter Width (mm) (mm) W1 (mm) B0 (mm) K0 (mm) P1 (mm) W Pin1 (mm) Quadrant LP3878MRX-ADJ/NOPB SO Power PAD DDA 8 2500 330.0 12.4 6.5 5.4 2.0 8.0 12.0 Q1 LP3878SD-ADJ/NOPB WSON NGT 8 1000 180.0 12.4 4.3 4.3 1.1 8.0 12.0 Q1 LP3878SDX-ADJ/NOPB WSON NGT 8 4500 330.0 12.4 4.3 4.3 1.1 8.0 12.0 Q1 Pack Materials-Page 1 PACKAGE MATERIALS INFORMATION www.ti.com 5-Jan-2021 *All dimensions are nominal Device Package Type Package Drawing Pins SPQ Length (mm) Width (mm) Height (mm) LP3878MRX-ADJ/NOPB SO PowerPAD DDA 8 2500 367.0 367.0 35.0 LP3878SD-ADJ/NOPB WSON NGT 8 1000 200.0 183.0 25.0 LP3878SDX-ADJ/NOPB WSON NGT 8 4500 346.0 346.0 35.0 Pack Materials-Page 2 PACKAGE OUTLINE DDA0008B PowerPAD TM SOIC - 1.7 mm max height SCALE 2.400 PLASTIC SMALL OUTLINE C 6.2 TYP 5.8 A SEATING PLANE PIN 1 ID AREA 0.1 C 6X 1.27 8 1 2X 3.81 5.0 4.8 NOTE 3 4 5 8X B 4.0 3.8 NOTE 4 0.51 0.31 0.25 1.7 MAX C A B 0.25 TYP 0.10 SEE DETAIL A 5 4 EXPOSED THERMAL PAD 3.4 2.8 0.25 GAGE PLANE 9 8 1 0 -8 0.15 0.00 1.27 0.40 DETAIL A 2.71 2.11 TYPICAL 4214849/A 08/2016 PowerPAD is a trademark of Texas Instruments. NOTES: 1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing per ASME Y14.5M. 2. This drawing is subject to change without notice. 3. This dimension does not include mold flash, protrusions, or gate burrs. Mold flash, protrusions, or gate burrs shall not exceed 0.15 mm per side. 4. This dimension does not include interlead flash. Interlead flash shall not exceed 0.25 mm per side. 5. Reference JEDEC registration MS-012. www.ti.com EXAMPLE BOARD LAYOUT DDA0008B PowerPAD TM SOIC - 1.7 mm max height PLASTIC SMALL OUTLINE (2.95) NOTE 9 SOLDER MASK DEFINED PAD (2.71) SOLDER MASK OPENING SEE DETAILS 8X (1.55) 1 8 8X (0.6) 9 SYMM (1.3) TYP (3.4) SOLDER MASK OPENING (4.9) NOTE 9 6X (1.27) 5 4 (R0.05) TYP METAL COVERED BY SOLDER MASK SYMM ( 0.2) TYP VIA (1.3) TYP (5.4) LAND PATTERN EXAMPLE SCALE:10X 0.07 MIN ALL AROUND 0.07 MAX ALL AROUND SOLDER MASK OPENING METAL SOLDER MASK OPENING METAL UNDER SOLDER MASK SOLDER MASK DEFINED NON SOLDER MASK DEFINED SOLDER MASK DETAILS PADS 1-8 4214849/A 08/2016 NOTES: (continued) 6. Publication IPC-7351 may have alternate designs. 7. Solder mask tolerances between and around signal pads can vary based on board fabrication site. 8. This package is designed to be soldered to a thermal pad on the board. For more information, see Texas Instruments literature numbers SLMA002 (www.ti.com/lit/slma002) and SLMA004 (www.ti.com/lit/slma004). 9. Size of metal pad may vary due to creepage requirement. 10. Vias are optional depending on application, refer to device data sheet. If any vias are implemented, refer to their locations shown on this view. It is recommended that vias under paste be filled, plugged or tented. www.ti.com EXAMPLE STENCIL DESIGN DDA0008B PowerPAD TM SOIC - 1.7 mm max height PLASTIC SMALL OUTLINE (2.71) BASED ON 0.125 THICK STENCIL 8X (1.55) (R0.05) TYP 1 8 8X (0.6) (3.4) BASED ON 0.125 THICK STENCIL 9 SYMM 6X (1.27) 5 4 METAL COVERED BY SOLDER MASK SYMM (5.4) SEE TABLE FOR DIFFERENT OPENINGS FOR OTHER STENCIL THICKNESSES SOLDER PASTE EXAMPLE EXPOSED PAD 100% PRINTED SOLDER COVERAGE BY AREA SCALE:10X STENCIL THICKNESS SOLDER STENCIL OPENING 0.1 0.125 0.150 0.175 3.03 X 3.80 2.71 X 3.40 (SHOWN) 2.47 X 3.10 2.29 X 2.87 4214849/A 08/2016 NOTES: (continued) 11. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. IPC-7525 may have alternate design recommendations. 12. Board assembly site may have different recommendations for stencil design. www.ti.com PACKAGE OUTLINE NGT0008A WSON - 0.8 mm max height SCALE 3.000 PLASTIC SMALL OUTLINE - NO LEAD 4.1 3.9 A B PIN 1 INDEX AREA 4.1 3.9 C 0.8 MAX SEATING PLANE 0.05 0.00 0.08 C EXPOSED THERMAL PAD 2.6 0.05 (0.2) TYP 4 2X 2.4 5 SYMM 9 3 0.05 8 1 6X 0.8 PIN 1 ID 8X SYMM 8X 0.5 0.3 0.35 0.25 0.1 0.05 C A B C 4214935/A 08/2020 NOTES: 1. All linear dimensions are in millimeters. Any dimensions in parenthesis are for reference only. Dimensioning and tolerancing per ASME Y14.5M. 2. This drawing is subject to change without notice. 3. The package thermal pad must be soldered to the printed circuit board for thermal and mechanical performance. www.ti.com EXAMPLE BOARD LAYOUT NGT0008A WSON - 0.8 mm max height PLASTIC SMALL OUTLINE - NO LEAD (2.6) 8X (0.6) SYMM 1 8 8X (0.3) SYMM 9 (3) (1.25) 6X (0.8) 4 (R0.05) TYP 5 ( 0.2) VIA TYP (1.05) (3.8) LAND PATTERN EXAMPLE EXPOSED METAL SHOWN SCALE:15X 0.07 MIN ALL AROUND 0.07 MAX ALL AROUND EXPOSED METAL SOLDER MASK OPENING METAL EXPOSED METAL METAL UNDER SOLDER MASK NON SOLDER MASK DEFINED (PREFERRED) SOLDER MASK OPENING SOLDER MASK DEFINED SOLDER MASK DETAILS 4214935/A 08/2020 NOTES: (continued) 4. This package is designed to be soldered to a thermal pad on the board. For more information, see Texas Instruments literature number SLUA271 (www.ti.com/lit/slua271). 5. Vias are optional depending on application, refer to device data sheet. If any vias are implemented, refer to their locations shown on this view. It is recommended that vias under paste be filled, plugged or tented. www.ti.com EXAMPLE STENCIL DESIGN NGT0008A WSON - 0.8 mm max height PLASTIC SMALL OUTLINE - NO LEAD (0.675) SYMM 8X (0.6) METAL TYP 1 8 8X (0.3) (0.755) 9 SYMM (1.31) 6X (0.8) 5 4 (R0.05) TYP (1.15) (3.8) SOLDER PASTE EXAMPLE BASED ON 0.125 mm THICK STENCIL EXPOSED PAD 9: 77% PRINTED SOLDER COVERAGE BY AREA UNDER PACKAGE SCALE:20X 4214935/A 08/2020 NOTES: (continued) 6. Laser cutting apertures with trapezoidal walls and rounded corners may offer better paste release. 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