LP2981 LP2981 Micropower 100 mA Ultra Low-Dropout Regulator in SOT-23 Package Literature Number: SNOS773J LP2981 Micropower 100 mA Ultra Low-Dropout Regulator in SOT-23 Package General Description Features The LP2981 is a 100 mA, fixed-output voltage regulator designed specifically to meet the requirements of battery-powered applications. Using an optimized VIP® (Vertically Integrated PNP) process, the LP2981 delivers unequaled performance in all specifications critical to battery-powered designs: Dropout Voltage. Typically 200 mV @ 100 mA load, and 7 mV @ 1 mA load. Ground Pin Current. Typically 600 μA @ 100 mA load, and 80 μA @ 1 mA load. Sleep Mode. Less than 1 μA quiescent current when ON/ OFF pin is pulled low. Precision Output. 0.75% tolerance output voltages available (A grade). Nine voltage options, from 2.5V to 5.0V, are available as standard products. ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Ultra low dropout voltage Output voltage accuracy 0.75% (A Grade) Guaranteed 100 mA output current < 1 μA quiescent current when shutdown Low ground pin current at all load currents High peak current capability (300 mA typical) Wide supply voltage range (16V max) Fast dynamic response to line and load Low ZOUT over wide frequency range Overtemperature/overcurrent protection −40°C to +125°C junction temperature range Applications ■ ■ ■ ■ Cellular Phone Palmtop/Laptop Computer Personal Digital Assistant (PDA) Camcorder, Personal Stereo, Camera Block Diagram 1250601 VIP® is a registered trademark of National Semiconductor Corporation. © 2009 National Semiconductor Corporation 12506 www.national.com LP2981 Micropower 100 mA Ultra Low-Dropout Regulator in SOT-23 Package January 15, 2009 LP2981 Connection Diagram 5-Lead Small Outline Package (SOT-23) 1250602 Top View See NS Package Number MF05A Pin Descriptions Name Pin Number VIN 1 Input Voltage Function GND 2 Common Ground (device substrate) ON/OFF 3 Logic high enable input N/C 4 Post package trim - do not connect to this pin VOUT 5 Regulated output voltage www.national.com 2 LP2981 Ordering Information TABLE 1. Package Marking and Order Information Output Voltage (V) Grade A 2.5 STD 2.7 A STD A 2.8 STD A 3.0 STD 3.2 A A 3.3 STD A 3.6 STD 3.8 A STD A 5.0 STD Order Information Package Marking LP2981AIM5X-2.5 L0CA 3000 Units on Tape and Reel LP2981AIM5-2.5 L0CA 1000 Units on Tape and Reel LP2981IM5X-2.5 L0CB 3000 Units on Tape and Reel LP2981IM5-2.5 L0CB 1000 Units on Tape and Reel LP2981AIM5X-2.7 L0DA 3000 Units on Tape and Reel LP2981AIM5-2.7 L0DA 1000 Units on Tape and Reel LP2981IM5-2.7 L0DB 1000 Units on Tape and Reel LP2981AIM5X-2.8 L77A 3000 Units on Tape and Reel LP2981AIM5-2.8 L77A 1000 Units on Tape and Reel LP2981IM5X-2.8 L77B 3000 Units on Tape and Reel LP2981IM5-2.8 L77B 1000 Units on Tape and Reel LP2981AIM5X-3.0 L05A 3000 Units on Tape and Reel LP2981AIM5-3.0 L05A 1000 Units on Tape and Reel LP2981IM5X-3.0 L05B 3000 Units on Tape and Reel LP2981IM5-3.0 L05B 1000 Units on Tape and Reel LP2981AIM5X-3.2 L35A 3000 Units on Tape and Reel LP2981AIM5X-3.3 L04A 3000 Units on Tape and Reel LP2981AIM5-3.3 L04A 1000 Units on Tape and Reel LP2981IM5X-3.3 L04B 3000 Units on Tape and Reel LP2981IM5-3.3 L04B 1000 Units on Tape and Reel LP2981AIM5X-3.6 L0JA 3000 Units on Tape and Reel LP2981AIM5-3.6 L0JA 1000 Units on Tape and Reel LP2981IM5X-3.6 L0JB 3000 Units on Tape and Reel LP2981IM5-3.6 L0JB 1000 Units on Tape and Reel LP2981AIM5-3.8 L36A 1000 Units on Tape and Reel Supplied as: LP2981IM5-3.8 L36B 1000 Units on Tape and Reel LP2981AIM5X-5.0 L03A 3000 Units on Tape and Reel LP2981AIM5-5.0 L03A 1000 Units on Tape and Reel LP2981IM5X-5.0 L03B 3000 Units on Tape and Reel LP2981IM5-5.0 L03B 1000 Units on Tape and Reel 3 www.national.com LP2981 ESD Rating (Note 2) 2 kV Power Dissipation (Note 3) Internally Limited Input Supply Voltage (Survival) −0.3V to +16V Input Supply Voltage (Operating) 2.1V to +16V Shutdown Input Voltage (Survival) −0.3V to +16V Output Voltage (Survival, (Note 4)) −0.3V to +9V IOUT (Survival) Short Circuit Protected Input-Output Voltage (Survival, (Note 5) −0.3V to +16V Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. Storage Temperature Range Operating Junction Temperature Range Lead Temperature (Soldering, 5 sec.) −65°C to +150°C −40°C to +125°C 260°C Electrical Characteristics Limits in standard typeface are for TJ = 25°C, and limits in boldface type applyover the full operating temperature range. Unless otherwise specified: VIN = VO(NOM) + 1V, CIN = 1 μF, IL = 1 mA, COUT = 4.7 μF,VON/OFF = 2V. Symbol ΔVO Parameter Conditions Typ Output Voltage Tolerance IL = 1mA 1 mA < IL < 100 mA VIN–VO Output Voltage VO(NOM) + 1V Line Regulation ≤ VIN ≤ 16V Dropout Voltage IL = 0 LP2981AI-XX (Note 6) Min Max Min Max −0.75 0.75 −1.25 1.25 −1.0 1.0 −2.0 2.0 −2.5 2.5 −3.5 3.5 0.007 1 (Note 7) IL = 1 mA IGND Ground Pin Current 7 IL = 25 mA 70 IL = 100 mA 200 IL = 0 65 IL = 1 mA 80 IL = 25 mA VON/OFF ION/OFF LP2981I-XX (Note 6) 200 0.014 0.014 0.032 0.032 3 3 5 5 10 10 15 15 100 100 150 150 250 250 375 375 95 95 125 125 110 110 170 170 300 300 550 550 800 800 IL = 100 mA 600 1500 1500 VON/OFF < 0.3V 0.01 0.8 0.8 VON/OFF < 0.15V 0.05 2 2 ON/OFF Input Voltage High = O/P ON 1.4 (Note 8) Low = O/P OFF 0.50 0.15 0.15 ON/OFF Input Current VON/OFF = 0 0.01 −1 −1 5 15 15 VON/OFF = 5V 1.6 Units %VNOM %/V mV μA V 1.6 μA IO(PK) Peak Output Current VOUT ≥ VO(NOM) − 5% 400 en Output Noise BW = 300 Hz–50 kHz, 160 μV Voltage (RMS) COUT = 10 μF Ripple Rejection f = 1 kHz 63 dB 150 mA 150 150 mA COUT = 10 μF IO(MAX) Short Circuit Current RL = 0 (Steady State) (Note 9) www.national.com 4 Note 2: The ESD rating of pins 3 and 4 for the SOT-23 package is 1 kV. Note 3: The maximum allowable power dissipation is a function of the maximum junction temperature, TJ(MAX), the junction-to-ambient thermal resistance, θJA, and the ambient temperature, TA. The maximum allowable power dissipation at any ambient temperature is calculated using: The value of θJA for the SOT-23 package is 220°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 LP2981 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. Reversing the polarity from VIN to VOUT will turn on this diode (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: The ON/OFF inputs must be properly driven to prevent misoperation. For details, refer to Application Hints. Note 9: See Typical Performance Characteristics curve(s). Typical Application Circuit 1250604 *ON/OFF input must be actively terminated. Tie to VIN if this function is not to be used. **Minimum Output Capacitance is shown to insure stability over full load current range. More capacitance provides superior dynamic performance and additional stability margin (see Application Hints). ***Do not make connections to this pin. 5 www.national.com LP2981 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. LP2981 Typical Performance Characteristics Unless otherwise specified: TA = 25°C, VIN = VO(NOM) + 1V, COUT = 4.7 μF, CIN = 1 μF all voltage options, ON/OFF pin tied to VIN. Output Voltage vs Temperature Output Voltage vs Temperature 1250607 1250606 Output Voltage vs Temperature Dropout Characteristics 1250609 1250608 Dropout Characteristics Dropout Characteristics 1250610 1250611 www.national.com 6 LP2981 Dropout Voltage vs Temperature Dropout Voltage vs Load Current 1250612 1250613 Ground Pin Current vs Temperature Ground Pin Current vs Load Current 1250614 1250615 Input Current vs VIN Input Current vs VIN 1250617 1250616 7 www.national.com LP2981 Line Transient Response Line Transient Response 1250618 1250619 Load Transient Response Load Transient Response 1250621 1250620 Load Transient Response Load Transient Response 1250622 www.national.com 1250623 8 LP2981 Short Circuit Current Instantaneous Short Circuit Current vs Temperature 1250624 1250625 Short Circuit Current Instantaneous Short Circuit Current vs Output Voltage 1250626 1250627 Output Impedance vs Frequency Ripple Rejection 1250628 1250629 9 www.national.com LP2981 Output Noise Density Output Impedance vs Frequency 1250631 1250630 Input to Output Leakage vs Temperature Output Reverse Leakage vs Temperature 1250633 1250632 Turn-On Waveform Turn-Off Waveform 1250635 1250634 www.national.com 10 LP2981 ON/OFF Pin Current vs VON/OFF ON/OFF Threshold vs Temperature 1250637 1250636 11 www.national.com LP2981 Application Hints EXTERNAL CAPACITORS Like any low-dropout regulator, the external capacitors used with the LP2981 must be carefully selected to assure regulator loop stability. Input Capacitor: An input capacitor whose value is ≥ 1 μF is required with the LP2981 (amount of capacitance can be increased without limit). This capacitor must be located a distance of not more than 0.5″ from the input pin of the LP2981 and returned to a clean analog ground. Any good quality ceramic or tantalum can be used for this capacitor. Output Capacitor: The output capacitor must meet both the requirement for minimum amount of capacitance and E.S.R. (equivalent series resistance) value. Curves are provided which show the allowable ESR range as a function of load current for various output voltages and capacitor values (refer to Figures 1, 2, 3, 4). Important: The output capacitor must maintain its ESR in the stable region over the full operating temperature range to assure stability. Also, capacitor tolerance and variation with temperature must be considered to assure the minimum amount of capacitance is provided at all times. This capacitor should be located not more than 0.5″ from the output pin of the LP2981 and returned to a clean analog ground. 1250638 FIGURE 1. 5V/3.3 μF ESR Curves CAPACITOR CHARACTERISTICS Tantalum: Tantalum capacitors are the best choice for use with the LP2981. Most good quality tantalums can be used with the LP2981, but check the manufacturer's data sheet to be sure the ESR is in range. It is important to remember that ESR increases at lower temperatures and a capacitor that is near the upper limit for stability at room temperature can cause instability when it gets cold. In applications which must operate at very low temperatures, it may be necessary to parallel the output tantalum capacitor with a ceramic capacitor to prevent the ESR from going up too high (see next section for important information on ceramic capacitors). Ceramic: Ceramic capacitors are not recommended for use at the output of the LP2981. This is because the ESR of a ceramic can be low enough to go below the minimum stable value for the LP2981. A 2.2 μF ceramic was measured and found to have an ESR of about 15 mΩ, which is low enough to cause oscillations. If a ceramic capacitor is used on the output, a 1Ω resistor should be placed in series with the capacitor. Aluminum: Because of large physical size, aluminum electrolytics are not typically used with the LP2981. They must meet the same ESR requirements over the operating temperature range, more difficult because of their steep increase at cold temperature. An aluminum electrolytic can exhibit an ESR increase of as much as 50X when going from 20°C to −40°C. Also, some aluminum electrolytics are not operational below −25°C because the electrolyte can freeze. www.national.com 1250639 FIGURE 2. 5V/10 μF ESR Curves 1250640 FIGURE 3. 3V/3.3 μF ESR Curves 12 1250642 FIGURE 4. 3V/10 μF ESR Curves 1250643 REVERSE CURRENT PATH The internal PNP power transistor used as the pass element in the LP2981 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 (See Figure 5). FIGURE 6. Adding External Schottky Diode Protection ON/OFF INPUT OPERATION The LP2981 is shut off by pulling the ON/OFF input low, and turned on by driving the input high. If this feature is not to be used, the ON/OFF input should be tied to VIN to keep the regulator on at all times (the ON/OFF input must not be left floating). To ensure proper operation, the signal source used to drive the ON/OFF input must be able to swing above and below the specified turn-on/turn-off voltage thresholds which guarantee an ON or OFF state (see Electrical Characteristics). The ON/OFF signal may come from either a totem-pole output, or an open-collector output with pull-up resistor to the LP2981 input voltage or another logic supply. The high-level voltage may exceed the LP2981 input voltage, but must remain within the Absolute Maximum Ratings for the ON/OFF pin. It is also important that the turn-on/turn-off voltage signals applied to the ON/OFF input have a slew rate which is greater than 40 mV/μs. IMPORTANT: The regulator shutdown function will not operate correctly if a slow-moving signal is applied to the ON/OFF input. 1250641 FIGURE 5. LP2981 Reverse Current Path However, if the input voltage is more than a VBE below the output voltage, 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 the VIN pin and out the ground pin, which can damage the part. The internal diode can also be turned on if the input voltage is abruptly stepped down to a voltage which is a VBE below the output voltage. 13 www.national.com LP2981 In any application where the output voltage may be higher than the input voltage, an external Schottky diode must be connected from VIN to VOUT (cathode on VIN, anode on VOUT. See Figure 6), to limit the reverse voltage across the LP2981 to 0.3V (see Absolute Maximum Ratings) LP2981 Physical Dimensions inches (millimeters) unless otherwise noted 5-Lead Small Outline Package (SOT-23) NS Package Number MF05A For Order Numbers, refer to Table 1 in the “Ordering Information” section of this document. www.national.com 14 LP2981 Notes 15 www.national.com LP2981 Micropower 100 mA Ultra Low-Dropout Regulator in SOT-23 Package Notes For more National Semiconductor product information and proven design tools, visit the following Web sites at: Products Design Support Amplifiers www.national.com/amplifiers WEBENCH® Tools www.national.com/webench Audio www.national.com/audio App Notes www.national.com/appnotes Clock and Timing www.national.com/timing Reference Designs www.national.com/refdesigns Data Converters www.national.com/adc Samples www.national.com/samples Interface www.national.com/interface Eval Boards www.national.com/evalboards LVDS www.national.com/lvds Packaging www.national.com/packaging Power Management www.national.com/power Green Compliance www.national.com/quality/green Switching Regulators www.national.com/switchers Distributors www.national.com/contacts LDOs www.national.com/ldo Quality and Reliability www.national.com/quality LED Lighting www.national.com/led Feedback/Support www.national.com/feedback Voltage Reference www.national.com/vref Design Made Easy www.national.com/easy PowerWise® Solutions www.national.com/powerwise Solutions www.national.com/solutions Serial Digital Interface (SDI) www.national.com/sdi Mil/Aero www.national.com/milaero Temperature Sensors www.national.com/tempsensors Solar Magic® www.national.com/solarmagic Wireless (PLL/VCO) www.national.com/wireless Analog University® www.national.com/AU THE CONTENTS OF THIS DOCUMENT ARE PROVIDED IN CONNECTION WITH NATIONAL SEMICONDUCTOR CORPORATION (“NATIONAL”) PRODUCTS. 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