Lm317 Adjustable Voltage Regulator

Research about LM317 Positive adaptable Linear Voltage Regulator The LM317T is a 3-terminal integrated circuit which house supply a cut current of up to 1. 5 Amps with an fruit potential difference of in the midst of 1. 2V and 37 Volts. It accepts an input potential difference of between 3 and 40 volts. It can be used to regulate either current or voltage in situations where a amend current or fixed voltage is required. The level of current or voltage required can be disciplineed by connecting the chip in series with a fixed resistor and a potentiometer. The LM317 is also a popular variable voltage regulator.It was invented by Robert C. Dobkin and Robert J. Widlar in 1970 while they worked at National Semiconductor. Furthermore, both line and load regulation is better than standard fixed regulators. In addition to having higher performance than fixed regulators, this device includes on-chip current limiting, thermal overload protection, and impregnable operating- atomic num ber 18a protection. All overload protection remains fully functional, even if the adjust terminal is disconnected. The LM317 is versatile in its applications, including uses in programmable produce regulation and local on-card regulation.Or, by connecting a fixed resistor between the adjust and output terminals, the LM317 can function as a precision current regulator. An optional output optical condenser can be added to improve transient response. The adjust terminal can be bypassed to achieve actually high ripple-rejection ratios, which are difficult to achieve with standard three-terminal regulators. LM317 adaptable Voltage Regulator pin configuration. LM317 Adjustable Voltage Regulator Internal Block Diagram Operation of the LM317 Adjustable Voltage Regulator A constant 1. 5V reference voltage (VREF) produces a constant current (IREF) through R1 regardless of the value of R2. IREF = VREF / R1 In operation, the LM317 develops a nominal 1. 25V reference voltage, VREF, between t he output and adjustment terminal. The reference voltage is impressed crossways the resistor R1 and, since the voltage is constant, a constant current I1 then ply through the output send resistor R2, giving an output voltage of VOUT = VREF (1+ R2/R1) + IADJ R2 (The IADJ is typically a 50 A it is miserable in most applications and the input voltage should be 2-3V higher than with its output voltage. Application Information NOTES A. Ci is non required, but is recommended, particularly if the regulator is not in close proximity to the power-supply filter capacitors. A 0. 1-? F disc or 1-? F tantalum deliver the goodss sufficient bypassing for most applications, especially when adjustment and output capacitors are used. B. CO improves transient response, but is not needed for stability. C. The Output Voltage (Because IAdj typically is 50 ? A, it is negligible in most applications. ) D. CADJ is used to improve ripple rejection it prevents amplification of the ripple as the output v oltage is adjusted higher.If CADJ is used, it is best to include protection diodes. E. If the input is shorted to ground during a fault condition, protection diodes provide measures to prevent the possibility of external capacitors discharging through low-impedance paths in the IC. By providing low-impedance discharge paths for CO and CADJ, respectively, D1 and D2 prevent the capacitors from discharging into the output of the regulator. Schematic Diagram Solving for IREF IREF = VREF / R1 IREF = 1. 25V / 10000? IREF = 125mA Solving for VOUT(MIN) and VOUT(MAX)VOUT (MIN)/(MAX) = VREF (1+ R2/R1) + IADJ R2 VOUT(MIN) = 1. 25V (1+ 0? /10000? ) + 0. 000050A * 0? VOUT(MIN) = 1. 25V VOUT(MAX) = 1. 25V (1+ 50000? /10000? ) + 0. 000050A * 50000? VOUT(MAX) = 10V (Therefore, the tokenish input voltage that in order to supply its utmost output voltage is 12V. ) List of Components crap Type Symbol Material Description LM317 (IC) Adjustable Linear Voltage Regulator It is an adjustable three-te rminal confirmatory voltage regulator capable of supplying more than 1. 5A over an output-voltage range of 1. 5 V to 37 V. Potentiometer Variable Resistor Informally, a pot, in electronics technology is a element, a three-terminal resistor with a sliding contact that forms an adjustable voltage divider. If only two terminals are used, one end and the wiper, it acts as a variable resistor or rheostat. Ceramic Capacitor Unpolarized It is a two-terminal non-polar device that is constructed of alternating layers of surface and ceramic, with the ceramic material acting as the dielectric. Name Type Symbol Material Descriptionelectrolytic capacitor Polarized Formerly known as condenser, is a passive two-terminal electrical component used to line energy in an electric field. Resistor Carbon Film It is a passive two-terminal electrical component that implements electrical resistance as a circuit element. The current through a resistor is in direct proportion to the voltage ac ross the resistors terminals. Diode Rectifier It is a two-terminal electronic components that allow current to flow in only one direction, from an anode (+) to a cathode (-), and that convert AC to DC. Component Layout PCB Design Layout Conclusion I observed that the output voltage of the regulator (LM317) is depend on the R1 and R2 because when the R2 is set to minimum output resistance, the output voltage decrease to its minimum value that is equal to the voltage reference (VREF) while it is set to the maximum resistance, its output voltage will increase and it will reach its maximum output voltage that it can supply. As I said, that the output voltage can control and set it to the value that you desired or enough to supply a load or a circuit.