LM1117 1.0A Low Dropout Positive Voltage Regulator DESCRIPTION PIN CONFIGURATION The LM1117 is a series of low dropout voltage regulators which can provide up to 1A of output current. The LM1117 is available in four fixed voltage, 1.2V,1.8V, 3.3V and 5.0V. Additionally it is also available in adjustable version. On chip precision trimming adjusts the reference/ output voltage to within ±2%. Current limit is also trimmed to ensure specified output current and controlled short-circuit current. The LM1117 series is available in SOT-223 and TO-220 packages. A minimum of 10μF tantalum capacitor is required at the output to improve the transient response and stability. TO-220 FEATURES Adjustable and Fixed of 1.2V,1.8V, 3.3V, 5.0V Space saving SMD types of SOT-223 1.2V Drop-out Voltage 1.0A Output Current Line Regulation Typically at 0.2% max Current Limiting and Thermal Protection 1 2 3 SOT-223 1.ADJ/GND APPLICATION Post Regulator for switching DC/DC Converter High Efficiency Linear Regulator Battery Chargers 1 3 2 PC Add on Card Motherboard clock supplies Pin2 connected with heat sink LCD Monitor Set-top Box (Top View) 2.Output 3.Input ORDERING INFORMATION Temperature Range Package Orderable Device Package Qty LM1117T-1.2 LM1117T-1.8 LM1117T-2.5 TO-220-3L LM1117T-3.3 50Units/Tube LM1117T-5.0 LM1117T-ADJ 0°C +70°C Pb-Free LM1117MPX-1.2 LM1117MPX-1.8 LM1117MPX-2.5 SOT-223 LM1117MPX-3.3 LM1117MPX-5.0 LM1117MPX-ADJ Jan . 2008 Rev 1.2 1 2500Units/Tube LM1117 SCHEMATIC DIAGRAM Input SOA Current Limit Limiting Output Amplifier Sense Thermal Overload Voltage Adj / Com Regulation Reference Voltage Amplifier Figure 1. functional diagram ABSOLUTE MAXIMUM RATINGS Parameter Symbol Unit Value Input voltage VIN 15 V DC Output current Operating junction temperature range IOUT TJ PD/˄VIN-VO˅ mA Thermal resistance˄SOT-223˅ θJA Thermal resistance˄TO-220˅ Maximum power dissipation˄SOT-223˅ PD Maximum power dissipation˄TO-220˅ R C -25. to 125 150 R C/W 60 Internally limited mW RECOMMENDED OPERATING CONDITIONS Parameter Symbol DC Input Voltage VIN Operating Temperature, All Package Types TA Max Unit 1.224 15 V 0 May . 2008 Rev 1.0 Min 2 +70 R C LM1117 Parameter Reference LM1117T-ADJ Symbol VREF Voltage Test Conditions IO=10mA to 1.0A Min Typ Max Unit 1.225 1.250 1.280 V 1.176 1.200 1.224 V 1.764 1.800 1.836 2.45 2.500 2.55 3.240 3.300 3.360 4.900 5.000 5.100 0.1 0.2 2.0 7.0 2.0 7.0 2.0 7.0 Vin=2.8V to 1 2V LM1117T-1.2 IO=10mA to 1.0A Vin=2.7V to 12V LM1117T-1.8 IO=10mA to 1.0A Vin=3.3V to 12V Output LM1117T-2.5 VOUT Voltage IO=10mA to 1.0A Vin=4V to 12V LM1117T-3.3 IO=10mA to 1.0A Vin=4.8V to 12V LM1117T-5.0 IO=10mA to 1.0A Vin=6.5V to 15V LM1117T-ADJ IO=10mA % Vin=2.8V to 1 2V LM1117T-1.2 IO=10mA Vin=2.7V to 12V LM1117T-1.8 Line IO=10mA ∆VOUT Regulation LM1117T-2.5 Vin=3.3V to 12V IO=10mA mV Vin=4V to 12V LM1117T-3.3 IO=10mA 3.0 7.0 4.0 7.0 0.2 0.4 3.0 10.0 5.0 15.0 6.0 20.0 Vin=4.8V to 12V LM1117T-5.0 IO=10mA Vin=6.5V to 15V LM1117T-ADJ IO=10mA to 1.0A % Vin=2.8V LM1117T-1.2 IO=10mA to 1.0A Vin=2.7V LM1117T-1.8 Load IO=10mA to 1.0A ∆VOUT Regulation LM1117T-2.5 Vin=3.3V IO=10mA to 1.0A mV Vin=4V LM1117T-3.3 IO=10mA to 1.0A 6.0 20.0 7.0 25.0 IO=800mA 1.10 1.20 IO=1A 1.20 1.30 V 1250 1600 mA 50 120 μA Vin=4.8V LM1117T-5.0 IO=10mA to 1.0A Vin=6.5V Drop-out Voltage ∆V Current Limit ILIMIT Vin-Vout=1.5V Adjust pin Current IADJ IO=10mA 1000 Vin=1.4V to 10V Temperature Drift TS 0.5 May . 2008 Rev 1.0 3 % LM1117 RMS Output Noise RON Bandwidth in 60 70 dB 60 70 dB 10Hz to 10kHz Ripple Rejection Ratio RR 120Hz input CADJ=25μF, Vin-Vout=5V, IO=1.0A May. 2008 Rev 1.0 4 ripple, LM1117 TYPICAL PERFORMANCE CHARACTERISTICS 80 ,287 $ 50 40 COUT=10µF 30 10 Temperature(ºC) Figure 2. Temperature Stability 100 1K 10K 100K 1M Frequency(Hz) Figure 3. Ripple Rejection(with CADJ 25µF) 100 5 Tj=125ºC 4 3 Tj=25ºC 2 Tj=0ºC Adjust Pin Current(μA) Minimum Operating Current (mA) COUT=25µF COUT=10µF 60 20 COUT=25µF 70 Ripple Rejection(dB) 1 1 2 3 4 5 80 60 40 20 -50 6 -25 0 25 50 75 100 125 Input/Output Differential Voltage(V) Temperature(ºC) Figure 4. Minimum Load Current(Adjustable) Figure 5. Adjust Pin Current 1.45 1.8 IO=800mA 1.6 1.4 Tj=0ºC 1.2 Tj=50ºC 1.0 Tj=125ºC 0.8 0.6 Dropout Voltage(V) Minimum Differential Voltage(V) Output Voltage Deviation(%) 1.35 1.25 1.15 0.4 1.05 0.2 0 200 400 600 800 1000 0 Output Current(mA) 40 60 80 100 120 140 Ambient Temperature(ºC) Figure 6. Dropout Voltage vs. Output Current Figure 7. Dropout Voltage vs. Temperature May. 2008 Rev 1.0 20 5 Output Voltage(V.AC)Load Current Output Voltage(V.AC) Input Voltage(V) LM1117 0.1 0.05 0 -0.05 Vin=5V CIN=1μF COUT=10μF(Tantalum) VOUT=3.3V -0.1 0.4A 0.1A Time(μs) 50 0 -50 COUT=10μF(Tantalum) VOUT=3.3V -100 70 60 0 10 20 30 40 50 Time(μs) Figure 8. Load Transient Response Figure 9. Line Transient Response APPLICATION INFORMATION External Capacitors/Stability Input Bypass Capacitor An input capacitor is recommended. A 10μF tantalum on the input is a suitable input bypassing for almost all applications. Adjust Terminal Bypass Capacitor The adjust terminal can be bypassed to ground with a bypass capacitor (CADJ) to improve ripple rejection. This bypass capacitor prevents ripple from being amplified as the output voltage is increased. At any ripple frequency, the impedance of the CADJ should be less than R1 to prevent the ripple from being amplified: (2π*fRIPPLE*CADJ) < R1 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. 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. Output Voltage The LM1117 adjustable version develops a 1.25V reference voltage, VREF, between the output and the adjust terminal. As shown in Figure 10, 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. May. 2008 Rev 1.0 6 LM1117 LM1117-ADJ VOUT VIN VIN VOUT ADJ I1 VREF R1 10μF 100μF IADJ R2 VOUT=VREF(1+ R2 )+IADJR2 R1 Figure 10. Basic Adjustable Regulator 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. Figure 11, shows a typical application using a fixed output regulator. The Rt1 and Rt2 are the line resistances. It is obvious that the VLOAD 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. LM1117-XX VIN IL Rt1 VOUT VIN GND VOUT VLOAD RLOAD Rt2 VLOAD=VOUT-IL(Rt1+Rt2) Figure 11. Typical Application using Fixed Output Regulator When the adjustable regulator is used (Figure 12), 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 0.05Ωx 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. Rt1 VIN LM1117-ADJ VOUT VIN VOUT ADJ VREF R1 VLOAD RLOAD R2 IL Rt2 VLOAD=VREF(R1+ R2) / R1 - IL Rt1 Figure 12. Best Load Regulation Using Adjustable Output Regulator May. 2008 Rev 1.0 7 LM1117 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 an output capacitor is connected to a regulator and the input is shorted to ground, the output capacitor will discharge 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 VIN. 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 (≥1000μF), 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 13. 1N4002 (Optional) LM1117-ADJ VIN VOUT VIN VOUT ADJ COUT 100μF R1 Cadj 10μF R2 Figure 13. Regulator With Protection Diode Heat sink 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 temperatureˈrises from the semiconductor junction to the operating environment. A one-dimensional steady-state model of conduction heat transfer is demonstrated in Figure 14. 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 heat sink. RθJC(Component Variables) RθCA (Application Variables) Lead frame Size & Material Mounting Pad Size, Material, & Location No. of Conduction Pins Placement of Mounting Pad Die Size PCB Size & Material Traces Length & Width Die Attach Material Molding Compound Size and Material Adjacent Heat Sources Volume of Air Ambient Temperature Shape of Mounting Pad May. 2008 Rev 1.0 8 LM1117 RθJA=RθJC+RθCA Lead Frame Die RθCA Molded Package RθJC TA=25°C Board Via Extended Cooper Plane Mounting Pad Figure 14. 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 overheating. Under all possible operating conditions, the junction temperature of the LM1117 must be within the range of 0°C to 125°C. A heat sink may be required depending on the maximum power dissipation and maximum ambient temperature of the application. To determine if a heat sink is needed, the power dissipated by the regulator, PD , must be calculated: IIN = IL + IG PD = (VIN-VOUT)IL + VINIG Figure 15 shows the voltages and currents which are present in the circuit. IIN VIN VOUT OUT IN IL GND LOAD IG Figure 15. Power Dissipation Diagram 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, no heat-sink is needed since the package alone will dissipate enough heat to satisfy these requirements. If the calculated value for θJA falls below these limits, a heat-sink is required. As a design aid, Table 1 shows the value of the θJA of SOT-223 for different heat-sink area. May. 2008 Rev 1.0 9 LM1117 Table 1 θJA Different Heat-sink Area Layout 1 2 3 4 5 6 7 Copper Area Bottom Side (in²) Top Side (in²)* 0.0123 0 0 0.066 0 0.3 0 0.53 0.76 0 0 1 0.2 0.4 0.6 0.8 1 0 0 0 0 0 8 9 10 11 12 0.066 0.175 0.284 0.392 0.066 0.175 0.284 0.392 13 14 15 16 0.5 0.5 * Tab of device attached to topside copper. May. 2008 Rev 1.0 10 Thermal Resistance θJA,°C/W, SOT-223 136 123 84 75 69 66 115 98 89 82 79 125 93 83 75 70 LM1117 TYPICAL APPLICATION CIRCUIT 110Ω 110Ω LM1117-XX IN 4.75V to 5.25V 110Ω 18 to 27 LINES OUT GND + 10μF 22μF + 110Ω Figure 16. Active Terminator for SCSI-2 Bus LM1117-XX VOUT VIN 10μF* Tantalum GND 10μF Tantalum *Required if the regulator is located far from the power supply filter. Figure 17. Fixed Output Regulator VIN VO LM1117 (Adj) C2 R1 + 10μF + C1 10μF + C3 10μF R2 Figure 18. Adjustable- Voltage Model May. 2008 Rev 1.0 11 Load LM1117 PHYSICAL DIMENSIONS TO-220 B4 B5 B2 B1 θ1 A1 A3 A A3 A2 B3 B D2 D1 θ2 C3 C1 C C2 θ3 θ4 D Symbol Dimension(mm) Min Symbol Max Dimension(mm) Min Max 0.81(TYP) 2.56 C1 C2 C3 D 2.60(TYP) 0.38(TYP) 4.58(TYP) 9.20(TYP) B1 8.20(TYP) 3.65(TYP) D1 D2 Ø3.84(TYP) Ø1.50(TYP) B2 3.55(TYP) B3 2.74(TYP) θ1 θ2 3º(TYP) 3º(TYP) B4 13.00(TYP) θ3 3º(TYP) θ4 3º(TYP) A A1 A2 A3 B 10.10 2.51 15.47 B5 C 10.14 1.27(TYP) 15.51 1.27(TYP) May. 2008 Rev 1.0 12 LM1117 SOT-223 A θ4 E B2 B1 E1 E2 B A2 F A1 θ6 C1 θ3 A3 D D1 R 0 .3 F1 θ5 θ2 θ1 C Symbol A A1 A2 A3 B Dimension(mm) Min Max 2.96 3.02 Symbol E E1 E2 F F1 2.28 0.74 0.68 4.57 Dimension(mm) Min Max 0.30 0.09 0.03 0.30 4.63 1.00 0.90 B1 1.70 3.45 1.80 3.55 B2 6.90 7.10 θ1 θ2 C 6.45 6.55 θ3 13º C1 6.35 6.45 D D1 0.67 1.55 0.72 1.65 θ4 θ5 θ6 37.5º 13º May. 2008 Rev 1.0 13 13º 3º 9º 13º