LM1117 800mA Low-dropout Linear Regulator LM1117 800mA Low-Dropout Linear Regulator General Description Features The LM1117 is a series of low dropout voltage regulators with a dropout of 1.2V at 800mA of load current. It has the same pin-out as National Semiconductor’s industry standard LM317. The LM1117 is available in an adjustable version, which can set the output voltage from 1.25V to 13.8V with only two external resistors. In addition, it is also available in three fixed voltages, 2.85V, 3.3V, and 5V. n n n n n n n The LM1117 offers current limiting and thermal shutdown. Its circuit includes a zener trimmed bandgap reference to assure output voltage accuracy to within ± 1%. The LM1117 series is available in SOT-223, TO-220, and TO-252 D-PAK packages. A minimum of 10µF tantalum capacitor is required at the output to improve the transient response and stability. Applications n n n n n Available in 2.85V, 3.3V, 5V, and Adjustable Versions Space Saving SOT-223 Package Current Limiting and Thermal Protection Output Current 800mA Temperature Range 0˚C to 125˚C Line Regulation 0.2% (Max) Load Regulation 0.4% (Max) 2.85V Model for SCSI-2 Active Termination Post Regulator for Switching DC/DC Converter High Efficiency Linear Regulators Battery Charger Battery Powered Instrumentation Typical Application Active Terminator for SCSI-2 Bus Fixed Output Regulator 1 LM1117 800mA Low-dropout Linear Regulator Ordering Information Package 3-lead SOT-223 3-lead TO-220 Temperature Range Packing 0˚C to +125˚C LM1117-ADJ-223 Tape and Reel LM1117-2.85-223 Tape and Reel LM1117-3.3-223 Tape and Reel LM1117-5.0-223 Tape and Reel LM1117-ADJ-220 Rails 5 lead available LM1117-2.85-220 Rails suffix add 220-5L LM1117-3.3-220 Rails LM1117-5.0-220 3-lead TO-252 Rails LM1117-ADJ-252 Tape and Reel 5 lead available LM1117-2.85-252 Tape and Reel suffix add 252-5L LM1117-3.3-252 Tape and Reel LM1117-5.0-252 Tape and Reel Block Diagram 2 LM1117 800mA Low-dropout Linear Regulator Connection Diagrams SOT-223 DS100919-4 Top View TO-220 DS100919-2 Top View TO-252 DS100919-38 Top View 3 LM1117 800mA Low-dropout Linear Regulator Absolute Maximum Ratings (Note 1) If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications. TO-220 Package 260˚C, 10 sec SOT-223 Package 260˚C, 4 sec ESD Tolerance (Note 3) 2000V Operating Ratings (Note 1) Maximum Input Voltage (VIN to GND) LM1117-ADJ, LM1117-3.3, LM1117-5.0 20V Power Dissipation (Note 2) Internally Limited Junction Temperature (TJ ) (Note 2) 150˚C Storage Temperature Range Input Voltage (VIN to GND) LM1117-ADJ, LM1117-3.3, LM1117-5.0 15V LM1117-2.85 10V Junction Temperature Range (T J) (Note 2) -65˚C to 150˚C 0˚C to 125˚C Lead Temperature Electrical Characteristics Typicals and limits appearing in normal type apply for T tion temperature range for operation, 0˚C to 125˚C. Symbol VREF VOUT ∆VOUT ∆V OUT Output Voltage Line Regulation (Note 6) Load Regulation (Note 6) = 25˚C. Limits appearing in Boldface type apply over the entire juncMin (Note 5) Typ (Note 4) Max (Note 5) Units 1.238 1.225 1.250 1.250 1.262 1.270 V V LM1117-2.85 IOUT =10mA, VIN=4.85V, TJ=25˚C O≤I OUT≤800mA, 4.25V≤ VIN≤10V O≤IOUT ≤500mA, VIN=4.10V 2.820 2.790 2.790 2.850 2.850 2.850 2.880 2.910 2.910 V V V LM1117-3.3 I OUT=10mA, VIN=5V TJ=25˚C O≤I OUT≤800mA, 4.75V≤ VIN≤10V 3.267 3.235 3.300 3.300 3.333 3.365 V V LM1117-5.0 I OUT=10mA, VIN=7V, TJ=25˚C O≤I OUT≤ 800mA, 6.5V≤ VIN≤12V 4.950 4.900 5.000 5.000 5.050 5.100 V V Parameter Reference Voltage J Conditions LM1117-ADJ IOUT=10mA, VIN-VOUT=2V, TJ=25˚C 10mA≤I OUT≤ 800mA, 1.4V≤ VIN-VOUT≤10V LM1117-ADJ IOUT=10mA, 1.5V≤ VIN-VOUT≤13.75V 0.035 0.2 % LM1117-2.85 I OUT=0mA, 4.25V≤ VIN≤10V 1 6 mV LM1117-3.3 I OUT=0mA, 4.75V≤ VIN≤15V 1 6 mV LM1117-5.0 I OUT=0mA, 6.5V≤ VIN≤15V 1 10 mV LM1117-ADJ VIN-V OUT=3V, 10≤IOUT≤800mA 0.2 0.4 % LM1117-2.85 V IN=4.25V, 0≤IOUT≤800mA 1 10 mV LM1117-3.3 V IN=4.75V, 0≤IOUT≤800mA 1 10 mV LM1117-5.0 V IN=6.5V, 0≤IOUT≤800mA VIN-V OUT ILIMIT Dropout Voltage (Note 7) 1 15 mV IOUT=100mA 1.10 1.20 V IOUT=500mA 1.15 1.25 V IOUT=800mA 1.20 1.30 V 1200 1500 mA 1.7 5 mA Current Limit VIN-VOUT=5V, TJ=25˚C Minimum Load Current (Note 8) LM1117-ADJ VIN=15V 800 4 LM1117 800mA Low-dropout Linear Regulator Electrical Characteristics (Continued) Typicals and limits appearing in normal type apply for T tion temperature range for operation, 0˚C to 125˚C. Symbol = 25˚C. Limits appearing in Boldface type apply over the entire juncTyp (Note 4) Max (Note 5) Units LM1117-2.85 VIN≤10V 5 10 mA LM1117-3.3 V IN≤15V 5 10 mA Parameter Quiescent Current J Min (Note 5) Conditions LM1117-5.0 V IN≤15V Thermal Regulation TA=25˚C, 30ms Pulse Ripple Regulation fRIPPLE=120Hz, V IN-VOUT=3V VRIPPLE=1VPP Adjust Pin Current Adjust Pin Current Change 10≤ IOUT≤ 800mA, 1.4V≤ VIN-VOUT≤ 10V Temperature Stability 60 5 10 mA 0.01 0.1 %/W 75 dB 60 120 µA 0.2 5 µA 0.5 % 0.3 % (% of VOUT), 10Hz≤f≤10kHz 0.003 % Thermal Resistance Junction-to-Case 3-Lead SOT-223 3,5 -Lead TO-220 3,5 -Lead TO-252 15.0 3.0 10 ˚C/W ˚C/W ˚C/W Thermal Resistance Junction-to-Ambient (No heat sink; No air flow) 3-Lead SOT-223 3,5 -Lead TO-220 3,5 -Lead TO-252(Note 9) 136 79 92 ˚C/W ˚C/W ˚C/W Long Term Stability TA=125˚C, 1000Hrs RMS Output Noise Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics. Note 2: The maximum power dissipation is a function of TJ(max) , θJA, and TA. The maximum allowable power dissipation at any ambient temperature is PD = (TJ(max)–T A)/θJA. All numbers apply for packages soldered directly into a PC board. Note 3: For testing purposes, ESD was applied using human body model, 1.5kΩ in series with 100pF. Note 4: Typical Values represent the most likely parametric norm. Note 5: All limits are guaranteed by testing or statistical analysis. Note 6: Load and line regulation are measured at constant junction room temperature. Note 7: The dropout voltage is the input/output differential at which the circuit ceases to regulate against further reduction in input voltage. It is measured when the output voltage has dropped 100mV from the nominal value obtained at VIN=V OUT+1.5V. Note 8: The minimum output current required to maintain regulation. Note 9: Minimum pad size of 0.038in2 5 LM1117 800mA Low-dropout Linear Regulator Typical Performance Characteristics Dropout Voltage (VIN-V OUT) Short-Circuit Current DS100919-22 DS100919-23 Load Regulation LM1117-ADJ Ripple Rejection LM1117-ADJ Ripple Rejection vs. Current Temperature Stability 6 LM1117 800mA Low-dropout Linear Regulator Typical Performance Characteristics Adjust Pin Current (Continued) LM1117-2.85 Load Transient Response LM1117-5.0 Load Transient Response LM1117-2.85 Line Transient Response LM1117-5.0 Line Transient Response 7 LM1117 800mA Low-dropout Linear Regulator APPLICATION NOTE 1.0 External Capacitors/Stability 1.1 Input Bypass Capacitor Figure 2, shows a typical application using a fixed output regulator. The Rt1 and Rt2 are the line resistances. It is obvious that the V LOAD is less than the VOUT by the sum of the voltage drops along the line resistances. In this case, the load regulation seen at the RLOAD would be degraded from the data sheet specification. To improve this, the load should be tied directly to the output terminal on the positive side and directly tied to the ground terminal on the negative side. An input capacitor is recommended. A 10µF tantalum on the input is a suitable input bypassing for almost all applications. 1.2 Adjust Terminal Bypass Capacitor The adjust terminal can be bypassed to ground with a pass capacitor (CADJ) to improve ripple rejection. This pass capacitor prevents ripple from being amplified as output voltage is increased. At any ripple frequency, the pedance of the CADJ should be less than R1 to prevent ripple from being amplified: (2π*fRIPPLE*CADJ) < R1 bybythe imthe The R1 is the resistor between the output and the adjust pin. Its value is normally in the range of 100-200Ω. For example, with R1=124Ω and fRIPPLE=120Hz, the CADJ should be > 11µF. 1.3 Output Capacitor The output capacitor is critical in maintaining regulator stability, and must meet the required conditions for both minimum amount of capacitance and ESR (Equivalent Series Resistance). The minimum output capacitance required by the LM1117 is 10µF, if a tantalum capacitor is used. Any increase of the output capacitance will merely improve the loop stability and transient response. The ESR of the output capacitor should be less than 0.5Ω. In the case of the adjustable regulator, when the CADJ is used, a larger output capacitance (22µf tantalum) is required. 2.0 Output Voltage The LM1117 adjustable version develops a 1.25V reference voltage, VREF, between the output and the adjust terminal. As shown in Figure 1, this voltage is applied across resistor R1 to generate a constant current I1. The current IADJ from the adjust terminal could introduce error to the output. But since it is very small (60µA) compared with the I1 and very constant with line and load changes, the error can be ignored. The constant current I1 then flows through the output set resistor R2 and sets the output voltage to the desired level. For fixed voltage devices, R1 and R2 are integrated inside the devices. FIGURE 2. Typical Application using Fixed Output Regulator When the adjustable regulator is used (Figure 3), the best performance is obtained with the positive side of the resistor R1 tied directly to the output terminal of the regulator rather than near the load. This eliminates line drops from appearing effectively in series with the reference and degrading regulation. For example, a 5V regulator with 0.05Ω resistance between the regulator and load will have a load regulation due to line resistance of 0.05Ω x IL. If R1 (=125Ω) is connected near the load, the effective line resistance will be 0.05Ω (1+R2/R1) or in this case, it is 4 times worse. In addition, the ground side of the resistor R2 can be returned near the ground of the load to provide remote ground sensing and improve load regulation. FIGURE 3. Best Load Regulation using Adjustable Output Regulator 4.0 Protection Diodes Under normal operation, the LM1117 regulators do not need any protection diode. With the adjustable device, the internal resistance between the adjust and output terminals limits the current. No diode is needed to divert the current around the regulator even with capacitor on the adjust terminal. The adjust pin can take a transient signal of ± 25V with respect to the output voltage without damaging the device. When a output capacitor is connected to a regulator and the input is shorted to ground, the output capacitor will discharge FIGURE 1. Basic Adjustable Regulator 3.0 Load Regulation The LM1117 regulates the voltage that appears between its output and ground pins, or between its output and adjust pins. In some cases, line resistances can introduce errors to the voltage across the load. To obtain the best load regulation, a few precautions are needed. 8 LM1117 800mA Low-dropout Linear Regulator APPLICATION NOTE (Continued) into the output of the regulator. The discharge current depends on the value of the capacitor, the output voltage of the regulator, and rate of decrease of V IN. In the LM1117 regulators, the internal diode between the output and input pins can withstand microsecond surge currents of 10A to 20A. With an extremely large output capacitor (≥1000 µF), and with input instantaneously shorted to ground, the regulator could be damaged. In this case, an external diode is recommended between the output and input pins to protect the regulator, as shown in Figure 4. FIGURE 5. Cross-sectional view of Integrated Circuit Mounted on a printed circuit board. Note that the case temperature is measured at the point where the leads contact with the mounting pad surface The LM1117 regulators have internal thermal shutdown to protect the device from over-heating. Under all possible operating conditions, the junction temperature of the LM1117 must be within the range of 0˚C to 125˚C. A heatsink may be required depending on the maximum power dissipation and maximum ambient temperature of the application. To determine if a heatsink is needed, the power dissipated by the regulator, PD , must be calculated: IIN = IL + IG PD = (VIN-VOUT)I L + VINIG Figure 6 shows the voltages and currents which are present in the circuit. FIGURE 4. Regulator with Protection Diode 5.0 Heatsink Requirements When an integrated circuit operates with an appreciable current, its junction temperature is elevated. It is important to quantify its thermal limits in order to achieve acceptable performance and reliability. This limit is determined by summing the individual parts consisting of a series of temperature rises from the semiconductor junction to the operating environment. A one-dimensional steady-state model of conduction heat transfer is demonstrated in Figure 5. The heat generated at the device junction flows through the die to the die attach pad, through the lead frame to the surrounding case material, to the printed circuit board, and eventually to the ambient environment. Below is a list of variables that may affect the thermal resistance and in turn the need for a heatsink. RθJC(Component Variables) FIGURE 6. Power Dissipation Diagram RθCA (Application Variables) Leadframe Size & Material Mounting Pad Size, Material, & Location No. of Conduction Pins Placement of Mounting Pad Die Size PCB Size & Material Die Attach Material Traces Length & Width Molding Compound Size and Material Adjacent Heat Sources Volume of Air Ambient Temperatue Shape of Mounting Pad 9 LM1117 800mA Low-dropout Linear Regulator APPLICATION NOTE needed since the package alone will dissipate enough heat to satisfy these requirements. If the calculated value for θJA falls below these limits, a heatsink is required. As a design aid, Table 1 shows the value of the θJA of SOT223 and TO-252 for different heatsink area. The copper patterns that we used to measure these θJAs are shown at the end of the Application Notes Section. Figure 7 and Figure 8 reflects the same test results as what are in the Table 1 Figure 9 and Figure 10 shows the maximum allowable power dissipation vs. ambient temperature for the SOT-223 and TO-252 device. Figures Figure 11 and Figure 12 shows the maximum allowable power dissipation vs. copper area (in2) for the SOT-223 and TO-252 devices. Please see AN1028 for power enhancement techniques to be used with SOT-223 and TO-252 packages. (Continued) The next parameter which must be calculated is the maximum allowable temperature rise, TR(max): TR(max)=TJ(max)-TA(max) where TJ(max) is the maximum allowable junction temperature (125˚C), and TA(max) is the maximum ambient temperature which will be encountered in the application. Using the calculated values for TR(max) and PD, the maximum allowable value for the junction-to-ambient thermal resistance (θJA) can be calculated: θJA = TR(max)/PD If the maximum allowable value for θJA is found to be ≥136˚C/W for SOT-223 package or ≥79˚C/W for TO-220 package or ≥92˚C/W for TO-252 package, no heatsink is TABLE 1. θJA Different Heatsink Area Layout Copper Area Thermal Resistance Top Side (in2)* Bottom Side (in2) (θJA,˚C/W) SOT-223 (θJA,˚C/W) TO-252 1 0.0123 0 136 103 2 0.066 0 123 87 3 0.3 0 84 60 4 0.53 0 75 54 5 0.76 0 69 52 6 1 0 66 47 7 0 0.2 115 84 8 0 0.4 98 70 9 0 0.6 89 63 10 0 0.8 82 57 11 0 1 79 57 12 0.066 0.066 125 89 13 0.175 0.175 93 72 14 0.284 0.284 83 61 15 0.392 0.392 75 55 16 0.5 0.5 70 53 *Tab of device attached to topside copper FIGURE 8. θJA vs. 2oz Copper Area for TO-252 FIGURE 7. θJA vs. 1oz Copper Area for SOT-223 10 LM1117 800mA Low-dropout Linear Regulator APPLICATION NOTE FIGURE 9. Maximum Allowable Power Dissipation vs. Ambient Temperature for SOT-223 (Continued) FIGURE 10. Maximum Allowable Power Dissipation vs. Ambient Temperature for TO-252 FIGURE 12. Maximum Allowable Power Dissipation vs. 2oz Copper Area for TO-252 11 FIGURE 11. Maximum Allowable Power Dissipation vs. 1oz Copper Area for SOT-223 LM1117 800mA Low-dropout Linear Regulator Typical Application Circuits Adjusting Output of Fixed Regulators Regulator with Reference 5V Logic Regulator with Electronic Shutdown* 1.25V to 10V Adjustable Regulator with Improved Ripple Rejection Low Dropout Negative Supply Battery Backed-Up Regulated Supply Battery Backed-Up Regulated Supply 12 LM1117 800mA Low-dropout Linear Regulator Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 3-Lead TO-220 Package Physical Dimensions inches (millimeters) unless otherwise noted (Continued) 3-Lead TO-252 Package 13 LM1117 800mA Low-dropout Linear Regulator Physical Dimensions inches (millimeters) unless otherwise noted 3-Lead SOT-223 Package 14