LP2989LV Micropower 500 mA Low Noise Low Dropout Regulator for Applications with Output Voltages < 2V Designed for Use with Very Low ESR Output Capacitors General Description Features The LP2989LV is a 500 mA fixed-output voltage regulator designed to provide high performance and low noise in applications requiring output voltages < 2V. 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 LP2989LV delivers superior performance: Ground Pin Current: Typically 3 mA @ 500 mA load, and 110 µA @ 100 µA load. Sleep Mode: The LP2989LV 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 DS101357-1 VIP™ is a trademark of National Semiconductor Corporation. © 2000 National Semiconductor Corporation DS101357 www.national.com LP2989LV Micropower 500 mA Low Noise Low Dropout Regulator for Output Voltages < 2V Designed for Use with Very Low ESR Output Capacitors July 2000 LP2989LV Connection Diagram Surface Mount Packages: SO-8 Package Type M: See NS Package Drawing Number M08A DS101357-2 Ordering Information TABLE 1. Package Marking and Ordering Information for SO-8 (M) Devices Output Voltage Grade Order Information Package Marking Supplied as: 1.8 A LP2989AIMX-1.8 2989AIM1.8 2500 Units on Tape and Reel 1.8 A LP2989AIM-1.8 2989AIM1.8 Shipped in Anti-Static Rails 1.8 STD LP2989IMX-1.8 2989IM1.8 2500 Units on Tape and Reel 1.8 STD LP298IM-1.8 2989IM1.8 Shipped in Anti-Static Rails For output voltages ≥ 2V, see LP2989 datasheet. Basic Application Circuit DS101357-3 *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 = 10 µF, CIN = 1 µF, VS/D = 2V. Symbol VO VIN (min) IGND Parameter Output Voltage Tolerance Conditions Typical Units Min Max Min Max −0.75 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 0.4 VOUT = 1.8 IL ≤ 50 mA 1.96 VOUT = 1.8 IL = 250 mA 1.98 VOUT = 1.8 IL = 500 mA 2.11 Ground Pin Current LP2989I-X.X (Note 6) 1 mA < IL < 500 mA VO(NOM) + 1V ≤ VIN ≤ 16V Output Voltage Line Regulation Minimum Input Voltage Required To Maintain Output Regulation LP2989AI-X.X (Note 6) 0.005 IL = 100 µA 0.014 0.032 0.032 3 175 175 200 200 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 8) 1000 en Output Noise Voltage (RMS) BW = 100 Hz to 100 kHz, CBYPASS = .01 µF Ripple Rejection f = 1 kHz 3 %/V V 1 IL = 500 mA 0.014 %VNOM 110 IL = 200 mA %VNOM 600 µA mA µA 600 mA 18 µV(RMS) 60 dB www.national.com LP2989LV Absolute Maximum Ratings (Note 1) LP2989LV 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 = 10 µF, CIN = 1 µF, VS/D = 2V. Symbol Parameter Conditions Typical LP2989AI-X.X (Note 6) Min Output Voltage Temperature Coefficient Max LP2989I-X.X (Note 6) Min Units Max (Note 7) 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 VOH = 16V Output “LOW” Voltage VOUT = VO(NOM) − 0.5V IO(COMP) = 150 µA 0.001 150 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/W. 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 LP2989LV 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: Temperature coefficient is defined as the maximum (worst-case) change divided by the total temperature range. Note 8: See Typical Performance Characteristics curves. www.national.com 4 Unless otherwise specified: TA = 25˚C, COUT = 10 µF, CIN = 1 µF, S/D is tied to VIN, VIN = VO(NOM) + 1V, IL = 1 mA, VOUT = 1.8V. IGND vs Shutdown IGND vs Shutdown DS101357-7 IGND vs Shutdown DS101357-8 IGND vs Shutdown DS101357-9 Ground Pin Current vs Load Current DS101357-10 GND Pin Current vs Temperature and Load DS101357-22 DS101357-23 5 www.national.com LP2989LV Typical Performance Characteristics LP2989LV Typical Performance Characteristics Unless otherwise specified: TA = 25˚C, COUT = 10 µF, CIN = 1 µF, S/D is tied to VIN, VIN = VO(NOM) + 1V, IL = 1 mA, VOUT = 1.8V. (Continued) Short Circuit Current vs Temperature Short Circuit Current DS101357-34 DS101357-32 Short Circuit Current Minimum VIN vs Load Current DS101357-35 DS101357-39 www.national.com 6 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 LP2989LV 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 LP2989LV 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 LP2989LV 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 LP2989LV was designed to work with ceramic capacitors on the output to take advantage of the benefits they offer: for capacitance values in the 10 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 10 µF ceramic capacitor is in the range of 5 mΩ to 10 mΩ, which easily meets the ESR limits required for stability by the LP2989LV. 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 10 µF Y5V capacitor were used on the output since it will drop down to approximately 5 µF at high ambient temperatures (which could cause the LP2989LV to oscillate). If Z5U or Y5V capacitors are used on the output, a minimum capacitance value of 22 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 LP2989LV 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 10 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- DS101357-38 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 LP2989LV requires a minimum of 10 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 7 www.national.com LP2989LV operating temperature range. Some ceramic capacitors can exhibit large changes in capacitance with temperature, so X7R or X5R dielectric are strongly recommended. Application Hints LP2989LV Application Hints REVERSE INPUT-OUTPUT VOLTAGE (Continued) est of the three types listed, their capacitance is very stable with temperature, and DC leakage currrent is extremely low. The PNP power transistor used as the pass element in the LP2989LV has an inherent diode connected between the regulator output and input. 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. 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 LP2989LV 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 LP2989LV 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. www.national.com 8 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. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury to the user. National Semiconductor Corporation Americas Tel: 1-800-272-9959 Fax: 1-800-737-7018 Email: [email protected] www.national.com National Semiconductor Europe Fax: +49 (0) 180-530 85 86 Email: [email protected] Deutsch Tel: +49 (0) 69 9508 6208 English Tel: +44 (0) 870 24 0 2171 Français Tel: +33 (0) 1 41 91 8790 2. A critical component is any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. National Semiconductor Asia Pacific Customer Response Group Tel: 65-2544466 Fax: 65-2504466 Email: [email protected] National Semiconductor Japan Ltd. Tel: 81-3-5639-7560 Fax: 81-3-5639-7507 National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications. LP2989LV Micropower 500 mA Low Noise Low Dropout Regulator for Output Voltages < 2V Designed for Use with Very Low ESR Output Capacitors Physical Dimensions