LP2989 Micropower/Low Noise, 500 mA Ultra Low-Dropout Regulator For Use with Ceramic Output Capacitors General Description Features The LP2989 is a fixed-output 500 mA precision LDO regulator designed for use with ceramic output capacitors. Output noise can be reduced to 18µV (typical) by connecting an external 10 nF capacitor to the bypass pin. Using an optimized VIP™ (Vertically Integrated PNP) process, the LP2989 delivers superior performance: Dropout Voltage: Typically 310 mV @ 500 mA load, and 1 mV @ 100 µA load. Ground Pin Current: Typically 3 mA @ 500 mA load, and 110 µA @ 100 µA load. Sleep Mode: The LP2989 draws less than 0.8 µA quiescent current when shutdown pin is pulled low. Error Flag: The built-in error flag goes low when the output drops approximately 5% below nominal. Precision Output: Guaranteed output voltage accuracy is 0.75% (“A” grade) and 1.25% (standard grade) at room temperature. n n n n n n n n n n n Ultra low dropout voltage Guaranteed 500 mA continuous output current Very low output noise with external capacitor SO-8 surface mount package < 0.8 µA quiescent current when shutdown Low ground pin current at all loads 0.75% output voltage accuracy (“A” grade) High peak current capability (800 mA typical) Wide supply voltage range (16V max) Overtemperature/overcurrent protection −40˚C to +125˚C junction temperature range Applications n n n n Notebook/Desktop PC PDA/Palmtop Computer Wireless Communication Terminals SMPS Post-Regulator Block Diagram DS101339-1 VIP™ is a trademark of National Semiconductor Corporation. © 2000 National Semiconductor Corporation DS101339 www.national.com LP2989 Micropower/Low Noise, 500 mA Ultra Low-Dropout Regulator For Use with Ceramic Output Capacitors July 2000 LP2989 Connection Diagram Surface Mount Packages: SO-8 Package Type M: See NS Package Drawing Number M08A DS101339-2 Ordering Information TABLE 1. Package Marking and Ordering Information for SO-8 (M) Devices Output Voltage Grade Order Information Package Marking Supplied as: 2.5 A LP2989AIMX-2.5 2989AIM2.5 2500 Units on Tape and Reel 2.5 A LP2989AIM-2.5 2989AIM2.5 Shipped in Anti-Static Rails 2.5 STD LP2989IMX-2.5 2989IM2.5 2500 Units on Tape and Reel 2.5 STD LP2989IM-2.5 2989IM2.5 Shipped in Anti-Static Rails 3.3 A LP2989AIMX-3.3 2989AIM3.3 3.3 A LP2989AIM-3.3 2989AIM3.3 3.3 STD LP2989IMX-3.3 2989IM3.3 2500 Units on Tape and Reel 3.3 STD LP2989IM-3.3 2989IM3.3 Shipped in Anti-Static Rails 2500 Units on Tape and Reel Shipped in Anti-Static Rails Basic Application Circuit DS101339-3 *Capacitance values shown are minimum required to assure stability, but may be increased without limit. Larger output capacitor provides improved dynamic re- sponse. **Shutdown must be actively terminated (see App. Hints). Tie to INPUT (Pin4) if not used. www.national.com 2 Input Supply Voltage If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Input Supply Voltage (Operating) 2.1V to +16V Sense Pin −0.3V to +6V Storage Temperature Range −65˚C to +150˚C Operating Junction Temperature Range Output Voltage (Note 4) −40˚C to +125˚C IOUT (Survival) Lead Temperature 5 seconds) (Survival) −0.3V to +16V (Survival) −0.3V to +16V Short Circuit Protected (Soldering, Power Dissipation (Note 3) Input-Output Voltage (Note 5) 260˚C ESD Rating (Note 2) 2 kV (Survival) −0.3V to +16V Internally Limited Electrical Characteristics Limits in standard typeface are for TJ = 25˚C, and limits in boldface type apply over the full operating temperature range. Unless otherwise specified: VIN = VO(NOM) + 1V, IL = 1 mA, COUT = 4.7 µF, CIN = 1 µF, VS/D = 2V. Symbol VO Parameter Output Voltage Tolerance VIN–VO Conditions Typical Max Min Max 0.75 −1.25 1.25 −1.5 1.5 −2.5 2.5 −4.0 2.5 −5.0 3.5 1 mA < IL < 500 mA VO(NOM) + 1V ≤ VIN ≤ 16V −25˚C ≤ TJ ≤ 125˚C −3.5 2.5 −4.5 3.5 VO(NOM) + 1V ≤ VIN ≤ 16V Load Regulation 1 mA < IL < 500 mA Dropout Voltage (Note 7) IL = 100 µA 0.005 0.014 0.032 0.032 150 310 110 IL = 200 mA 1 IL = 500 mA 3 3 3 4 4 200 200 300 300 425 425 650 650 175 175 200 200 2 2 3.5 3.5 6 6 9 9 VS/D < 0.18V 0.5 2 2 VS/D < 0.4V 0.05 0.8 0.8 IO(PK) Peak Output Current VOUT ≥ VO(NOM) − 5% 800 IO(MAX) Short Circuit Current RL = 0 (Steady State) (Note 9) 1000 Output Noise Voltage (RMS) BW = 100 Hz to 100 kHz, COUT = 10 µF CBYPASS = .01 µF VOUT = 2.5V Ripple Rejection f = 1 kHz, COUT = 10 µF 3 %/V %VNOM 1 IL = 100 µA %VNOM 0.014 0.4 IL = 500 mA en Units Min −0.75 Output Voltage Line Regulation Ground Pin Current LP2989I-X.X (Note 6) 1 mA < IL < 500 mA VO(NOM) + 1V ≤ VIN ≤ 16V IL = 200 mA IGND LP2989AI-X.X (Note 6) 600 mV µA mA µA 600 mA 18 µV(RMS) 60 dB www.national.com LP2989 Absolute Maximum Ratings (Note 1) LP2989 Electrical Characteristics (Continued) Limits in standard typeface are for TJ = 25˚C, and limits in boldface type apply over the full operating temperature range. Unless otherwise specified: VIN = VO(NOM) + 1V, IL = 1 mA, COUT = 4.7 µF, CIN = 1 µF, VS/D = 2V. Symbol Parameter Conditions Typical LP2989AI-X.X (Note 6) Min Output Voltage Temperature Coefficient (Note 8) Max LP2989I-X.X (Note 6) Min Units Max 20 ppm/˚C SHUTDOWN INPUT VS/D IS/D S/D Input Voltage S/D Input Current VH = O/P ON 1.4 1.6 1.6 0.18 0.18 0.001 −1 −1 5 15 15 1 1 2 2 220 220 350 350 VL = O/P OFF IIN ≤ 2 µA 0.50 VS/D = 0 VS/D = 5V V µA ERROR COMPARATOR IOH VOL Output “HIGH” Leakage Output “LOW” Voltage VOH = 16V 0.001 VIN = VO(NOM) − 0.5V, IO(COMP) = 150 µA 150 VTHR (MAX) Upper Threshold Voltage VTHR (MIN) Lower Threshold Voltage −6.6 HYST Hysteresis 2.0 −4.8 −6.0 −3.5 −6.0 µA mV −3.5 −8.3 −2.5 −8.3 −2.5 −8.9 −4.9 −8.9 −4.9 −13.0 −3.0 −13.0 −3.0 %VOUT Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the device outside of its rated operating conditions. Note 2: ESD testing was performed using Human Body Model, a 100 pF capacitor discharged through a 1.5 kΩ resistor. Note 3: The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(MAX), the junction-to-ambient thermal resistance, θJ−A, and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature is calculated using: The value of θJ−A for the SO-8 (M) package is 160˚C. Exceeding the maximum allowable power dissipation will cause excessive die temperature, and the regulator will go into thermal shutdown. Note 4: If used in a dual-supply system where the regulator load is returned to a negative supply, the LP2989 output must be diode-clamped to ground. Note 5: The output PNP structure contains a diode between the VIN and VOUT terminals that is normally reverse-biased. Forcing the output above the input will turn on this diode and may induce a latch-up mode which can damage the part (see Application Hints). Note 6: Limits are 100% production tested at 25˚C. Limits over the operating temperature range are guaranteed through correlation using Statistical Quality Control (SQC) methods. The limits are used to calculate National’s Average Outgoing Quality Level (AOQL). Note 7: Dropout voltage is defined as the input to output differential at which the output voltage drops 100 mV below the value measured with a 1V differential. Note 8: Temperature coefficient is defined as the maximum (worst-case) change divided by the total temperature range. Note 9: See Typical Performance Characteristics curves. www.national.com 4 Unless otherwise specified: TA = 25˚C, COUT = 4.7 µF, CIN = 1 µF, S/D is tied to VIN, VIN = VO(NOM) + 1V, IL = 1 mA, VOUT = 2.5V. Input Current vs VIN Input Current vs VIN DS101339-5 IGND vs Shutdown DS101339-6 IGND vs Shutdown DS101339-7 IGND vs Shutdown DS101339-8 IGND vs Shutdown DS101339-9 DS101339-10 5 www.national.com LP2989 Typical Performance Characteristics LP2989 Typical Performance Characteristics Unless otherwise specified: TA = 25˚C, COUT = 4.7 µF, CIN = 1 µF, S/D is tied to VIN, VIN = VO(NOM) + 1V, IL = 1 mA, VOUT = 2.5V. (Continued) Line Transient Response Line Transient Response DS101339-11 Line Transient Response DS101339-26 Line Transient Response DS101339-15 Load Transient Response DS101339-16 Load Transient Response DS101339-17 www.national.com DS101339-18 6 Unless otherwise specified: TA = 25˚C, COUT = 4.7 µF, CIN = 1 µF, S/D is tied to VIN, VIN = VO(NOM) + 1V, IL = 1 mA, VOUT = 2.5V. (Continued) Dropout Voltage vs Load Current Dropout Voltage vs Temperature DS101339-20 DS101339-19 Dropout Characteristics Ground Pin Current vs Load Current DS101339-21 DS101339-22 GND Pin Current vs Temperature and Load VOUT vs Shutdown DS101339-24 DS101339-23 7 www.national.com LP2989 Typical Performance Characteristics LP2989 Typical Performance Characteristics Unless otherwise specified: TA = 25˚C, COUT = 4.7 µF, CIN = 1 µF, S/D is tied to VIN, VIN = VO(NOM) + 1V, IL = 1 mA, VOUT = 2.5V. (Continued) Input Current vs VIN Turn-ON Waveform DS101339-28 DS101339-25 Turn-ON Waveform Turn-ON Waveform DS101339-29 Turn-ON Waveform DS101339-30 Short Circuit Current vs Temperature DS101339-31 DS101339-32 www.national.com 8 Unless otherwise specified: TA = 25˚C, COUT = 4.7 µF, CIN = 1 µF, S/D is tied to VIN, VIN = VO(NOM) + 1V, IL = 1 mA, VOUT = 2.5V. (Continued) Short Circuit Current vs VOUT Short Circuit Current DS101339-34 DS101339-33 Short Circuit Current Output Noise Density DS101339-35 DS101339-36 Output Noise Density DS101339-37 9 www.national.com LP2989 Typical Performance Characteristics LP2989 Typical Performance Characteristics Unless otherwise specified: TA = 25˚C, COUT = 4.7 µF, CIN = 1 µF, S/D is tied to VIN, VIN = VO(NOM) + 1V, IL = 1 mA, VOUT = 2.5V. (Continued) Ripple Rejection Ripple Rejection DS101339-39 Ripple Rejection DS101339-40 Ripple Rejection DS101339-41 Ripple Rejection DS101339-42 Ripple Rejection DS101339-43 www.national.com DS101339-44 10 Unless otherwise specified: TA = 25˚C, COUT = 4.7 µF, CIN = 1 µF, S/D is tied to VIN, VIN = VO(NOM) + 1V, IL = 1 mA, VOUT = 2.5V. (Continued) Ripple Rejection Ripple Rejection In Dropout DS101339-46 DS101339-45 Ripple Rejection vs Load DS101339-47 11 www.national.com LP2989 Typical Performance Characteristics LP2989 operating temperature range. Some ceramic capacitors can exhibit large changes in capacitance with temperature, so X7R or X5R dielectric are strongly recommended. Application Hints EXTERNAL CAPACITORS The output capacitor must be located not more than 0.5″ from the output pin and returned to a clean analog ground. Like any low-dropout regulator, the LP2989 requires external capacitors for regulator stability. These capacitors must be correctly selected for good performance. NOISE BYPASS CAPACITOR: Connecting a 10 nF capacitor to the Bypass pin significantly reduces noise on the regulator output. However, the capacitor is connected directly to a high-impedance circuit in the bandgap reference. Because this circuit has only a few microamperes 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 polypropolene and polycarbonate film capacitors are available in small surface-mount packages and typically have extremely low leakage current. INPUT CAPACITOR: An input capacitor whose capacitance is ≥ 1 µF is required between the LP2989 input and ground (the amount of capacitance may be increased without limit). This capacitor must be located a distance of not more than 0.5″ from the input pin and returned to a clean analog ground. Any good quality ceramic, tantalum, or film capacitor may be used at the input. IMPORTANT: Tantalum capacitors can suffer catastrophic failure due to surge current when connected to a low-impedance source of power (like a battery or very large capacitor). If a Tantalum capacitor is used at the input, it must be guaranteed by the manufacturer to have a surge current rating sufficient for the application. There are no requirements for ESR on the input capacitor, but tolerance and temperature coefficient must be considered when selecting the capacitor to ensure the capacitance will be ≥ 1 µF over the entire operating temperature range. OUTPUT CAPACITOR: The LP2989 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 output capacitor whose ESR is as low as 5 mΩ. It may also be possible to use Tantalum or film capacitors at the output, but these are not as attractive for reasons of size and cost (see next section Capacitor Characteristics). The output capacitor must meet the requirement for minimum amount of capacitance and also have an ESR (equivalent series resistance) value which is within the stable range. Curves are provided which show the stable ESR range as a function of load current (see ESR graph below). CAPACITOR CHARACTERISTICS CERAMIC: The LP2989 was designed to work with ceramic capacitors on the output to take advantage of the benefits they offer: for capacitance values in the 4.7 µF 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 4.7 µF ceramic capacitor is in the range of 10 mΩ to 15 mΩ, which easily meets the ESR limits required for stability by the LP2989. One disadvantage of ceramic capacitors is that their capacitance can vary with temperature. Many large value ceramic capacitors (≥ 2.2 µF) are manufactured with the Z5U or Y5V temperature characteristic, which results in the capacitance dropping by more than 50% as the temperature goes from 25˚C to 85˚C. This could cause problems if a 4.7 µF capacitor were used on the output since it will drop down to approximately 2.4 µF at high ambient temperatures (which could cause the LP2989 to oscillate). If Z5U or Y5V capacitors are used on the output, a minimum capacitance value of 10 µF must be observed. A better choice for temperature coefficient in ceramic capacitors is X7R or X5R, which holds the capacitance within about ± 15% over the operating temperature range. TANTALUM: Tantalum output capacitors are not recommended for use with the LP2989 because: Tantalum capacitors are less desirable than ceramics for use as output capacitors because they are typically more expensive when comparing equivalent capacitance and voltage ratings in the 1 µF to 4.7 µF range. Another important consideration is that Tantalum capacitors have higher ESR values than equivalent size ceramics. This means that while it may be possible to find a Tantalum capacitor with an ESR value within the stable range, it would have to be larger in capacitance (which means bigger and more costly) than a ceramic capacitor with the same ESR value. It should also be noted that the ESR of a typical Tantalum will increase about 2:1 as the temperature goes from 25˚C down to −40˚C, so some guard band must be allowed. FILM: Polycarbonate and polypropelene film capacitors have excellent electrical performance: their ESR is the low- DS101339-38 Stable Region For output Capacitor ESR 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 LP2989 requires a minimum of 4.7 µF on the output (output capacitor size can be increased without limit). 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 www.national.com 12 CAUTION: the regulator output voltage can not be guaranteed if a slow-moving AC (or DC) signal is applied that is in the range between the specified turn-on and turn-off voltages listed under the electrical specification VON/OFF (see Electrical Characteristics). (Continued) est of the three types listed, their capacitance is very stable with temperature, and DC leakage currrent is extremely low. One disadvantage is that film capacitors are larger in physical size than ceramic or tantalum which makes film a poor choice for either input or output capacitors. REVERSE INPUT-OUTPUT VOLTAGE The PNP power transistor used as the pass element in the LP2989 has an inherent diode connected between the regulator output and input. During normal operation (where the input voltage is higher than the output) this diode is reverse-biased. However, if the output is pulled above the input, this diode will turn ON and current will flow into the regulator output. In such cases, a parasitic SCR can latch which will allow a high current to flow into VIN (and out the ground pin), which can damage the part. In any application where the output may be pulled above the input, an external Schottky diode must be connected from VIN to VOUT (cathode on VIN, anode on VOUT), to limit the reverse voltage across the LP2989 to 0.3V (see Absolute Maximum Ratings). However, their low leakage makes them a good choice for the noise bypass capacitor. Since the required amount of capacitance is only .01 µF, small surface-mount film capacitors are avalable in this size. SHUTDOWN INPUT OPERATION The LP2989 is shut off by driving 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 turn-on/turn-off voltage thresholds listed in the Electrical Characteristics section under VON/OFF. To prevent mis-operation, the turn-on (and turn-off) voltage signals applied to the Shutdown input must have a slew rate which is ≥ 40 mV/µs. 13 www.national.com LP2989 Application Hints LP2989 Micropower/Low Noise, 500 mA Ultra Low-Dropout Regulator For Use with Ceramic Output Capacitors Physical Dimensions inches (millimeters) unless otherwise noted SO-8 Package Type M NS Package Number M08A LIFE SUPPORT POLICY NATIONAL’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT AND GENERAL COUNSEL OF NATIONAL SEMICONDUCTOR CORPORATION. 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