How to use LM317 three terminal regulator tube to stabilize 5 volt DC

LM317 is an easy-to-use and widely used integrated regulator with variable output voltage. There are many models of the 317 series regulators: such as LM317HVH, W317L, etc.

Electronics enthusiasts often use the 317 regulator block to make regulated power supplies with variable output voltage. The output voltage of the regulated power supply can be calculated using the following formula, vo. Just from the formula itself, the resistance values of R1 and R2 can be set arbitrarily.

However, as a formula for calculating the output voltage of a regulated power supply, the resistance values of R1 and R2 cannot be set arbitrarily. Between the 1 and 2 pins is the voltage reference. To ensure the output performance of the regulator, R1 should be less than 240 ohms.

The voltage value of the regulator can be adjusted by changing the R2 resistance value. D1, D2 are used to protect LM317. First of all, the output voltage of the 317 regulator block is VO The output voltage of the 317 regulator block with high output voltage such as LM317HVA, LM317HVK, etc., the output voltage change range is VO, so the ratio range of R2 R1 can only be 0—.

It is very simple to use and requires only two external resistors to set the output voltage. In addition, it has better linear regulation and load regulation than standard fixed regulators. LM117 LM317 has built-in overload protection, safety zone protection and other protection circuits.

Secondly, the 317 regulator block has a minimum stable working current, some data are called the minimum output current, and some data are called the minimum discharge current. The value of the minimum stable operating current is generally . Due to the different manufacturers and models of 317 regulator blocks, its minimum stable working current is also different, but generally not greater than 5mA.

When the output current of the 317 regulator block is less than its minimum stable working current, the 317 regulator block cannot work normally. When the output current of the 317 regulator block is greater than its minimum stable working current, the 317 regulator block can output a stable DC voltage. If you do not pay attention to the minimum stable working current of the 317 regulator block when making the regulated power supply with the 317 regulator block (as shown in the figure), then the regulated power supply you make may have the following abnormal phenomena:

There is a big difference between the on-load voltage and the no-load voltage of the regulated power supply output. Normally, the LM117 LM317 does not require an external capacitor unless the input filter capacitor is more than 6 inches (about 15 cm) from the input of the LM117 LM317. The transient response can be altered by using output capacitors.

Using a filter capacitor on the adjustment side can achieve a much higher ripple rejection ratio than a standard three-terminal regulator. The input must be at least 2V higher than the output, otherwise the voltage cannot be regulated. The maximum input power should not exceed 40V.

The output current does not exceed 1A. If you input 12V, the output will be about 10V at most. Since it is still linearly regulated internally, the power consumption is relatively large.

When the input-input voltage difference is large and the output current is large, pay attention to the power consumption of 317 should not be too large. Generally, the power consumption does not exceed 20W after adding a heat sink. Therefore, when the pressure difference is large, it is recommended to adjust the pressure in different bins.

The current limit protection set inside the LM317 is that the maximum output current is also set, which cannot be changed. A voltage regulation of 2% is no problem, and the LM317 indicator will only be higher than that. The operating temperature range of LM317 is 0 125, and in the full temperature range, when the LM317 outputs the maximum current, the output voltage changes typically by 20mV and the maximum value is 70mV, from which it can be estimated that its equivalent internal resistance is significantly less.

The power transformer can choose a 25W transformer with an output voltage of 15V, and the peak output voltage of the secondary side in the case of 10% of the grid voltage is about 10%, and the voltage after bridge rectification and filtering is about or so, and the normal operation of LM317 requires a minimum of 3V input and output voltage difference, which is just a little leeway on the basis of 12V+3V, which is also necessary, because there is a small amount of ripple voltage to be taken into account.

C2 is used to prevent the internal self-oscillation of LM317, which is called the vibration cancellation capacitor. C3 is the filter capacitor of the regulator VD1, and the Songru digging VD1 provides the LM3173 pin reference voltage, which needs to be stabilized.

R1 is the discharge resistance of C3, for example, when the output voltage is adjusted from large to small, the stock voltage on C3 should be discharged, and the output voltage should be followed. VD2 protects LM317 from the back EMF breakdown of the load, such as when the inductive load is de-energized.

The middle wire of the transformer is the ground wire, and the ground of LM317 and LM337 is also connected there. The LM317 and LM337 are used as positive and negative power supplies respectively, and the circuit can make an adjustable positive and negative power supply to 12V. If you want to be positive 5V, take the LM317 output between the ground and the edge.

If you want to minus 5V, take the LM337 output between the output and the ground. The LM317 output and LM337 output can be taken up to 24V.

1, LM317T: TO-220 package shape, the output voltage range is, the maximum output current is, the minimum destabilization voltage (that is, the minimum voltage difference between the input and output) is the output terminal (3 pins) to the ground connected two series voltage divider resistors, the indirect point in the two resistors can be connected to the 1 pin of the integrated circuit, and the 2 pins are the input end. Changing the voltage divider ratio can adjust the output voltage.

3. The grounded voltage divider resistor is replaced with an adjustable resistor, and the output voltage can be continuously adjusted. The reference voltage of the LM317T is nominal), and the voltage divider resistance to ground is zero. The output voltage is equal to the reference voltage.

The grounding resistance is equal to the resistance between the terminals, and the output voltage is twice the reference voltage, that is, the resistance between the terminals is generally 240ohm, and the resistance is too small to affect the output voltage accuracy.

4. The voltage regulator made of 317 for the 0 to 30V adjustable DC regulated power supply composed of LM317 is limited by the circuit composition in the integrated block. The circuit shown in the attached diagram can make the voltage adjust from 0V onwards.

5. The difference between this circuit and the 317 basic application circuit is that a set of negative voltage auxiliary power supplies is added. The voltage of the positive pole of the regulator tube DW to the ground is 1 25V, the lower end of the voltage regulating potentiometer W is not connected to the ground terminal, but is connected to the positive pole of the regulator tube, and the output voltage of the voltage regulator power supply is still obtained from the output end of the three-terminal regulator and the ground.

6. In this way, when the resistance value of W is adjusted to zero, the voltage of 1 25V on R1 is just offset by the voltage of 1 25V on DW, so that the output voltage is 0V. The circuit can be adjusted from 0V, and the output voltage can reach more than 30V.

The power transformer can choose a 25W transformer with an output voltage of 15V, and the peak output voltage of the secondary side under the condition of 10% of the grid voltage is about about the voltage after bridge rectification and filtering.

The LM317 requires a minimum of 3V input and output voltage difference for normal operation, which is just a little leeway on the basis of 12V+3V, which is also necessary, because there is also a small amount of ripple voltage to be taken into account.

First of all, you need to have two 17-28V DC inputs, and use 2 resistors + LM317 to make a +15V power supply;

Make a -15V power supply with 2 resistors +LM337;

In fact, if you need a fixed plus or minus 15V, you can use LM7815 and LM7915 to do it, which is simpler (no need to connect a voltage divider resistor) and is also very cheap.

Summary. Hello, I'm glad to help you. The LM317T is a linear regulator device, and its input voltage must be DC voltage. When using the LM317T, in order to ensure its normal operation, the input voltage must be at least 2V higher than the output voltage, and the maximum value of the input voltage must not exceed the rated input voltage range of the LM317T.

Specifically, in general, the maximum input voltage of the LM317T is about 40V, and the specific input voltage range also needs to refer to the data sheet of the LM317T.

Hello, I'm glad to help you. The LM317T is a linear regulator device, and its input voltage must be base and this is the masked DC voltage. When using the LM317T, in order to ensure its normal operation, the input voltage must be at least 2V higher than the output voltage, and the maximum value of the input voltage must not exceed the rated input voltage range of the LM317T. Specifically, in general, the maximum input voltage of LM317T is about 40V, and the specific input voltage Fan Boxunwei also needs to refer to the data sheet of LM317T.

LM371 input DC voltage 9-12 volts what does it mean.

<>The LM371 is a linear regulator with an input voltage of between 9 and 12 volts. This means that if you want to use the LM371, you need to connect its input pins to a power supply with a DC voltage between 9 and 12 volts. If you set the input voltage to more than 12 volts, the LM371 will be overloaded and it will not work properly.

If the input voltage is lower than 9 volts, the LM371 will not be able to provide a stable output voltage, which will also cause it to not work properly.

Yes, but there are a few things to keep in mind:

1.The maximum input voltage of the LM317 and LM337 is 40V, if the input voltage exceeds this range, a voltage regulator needs to be added to step down.

2.The maximum supply voltage of the LM1875 is 25V, if the voltage is still exceeded after using the LM317 and LM337 voltage regulation, it is necessary to use a voltage splitting circuit to reduce the voltage.

3.The LM317 and LM337 have limited current output capabilities, and if the power of the equipment that needs to be powered is large, a higher power regulator is required.

4.When using LM317 and LM337 voltage regulation, it is necessary to pay attention to the heat dissipation problem, especially in the case of high voltage and high current, the voltage regulator will generate more heat, and it is necessary to choose the appropriate heat sink.

The LM1875 is a compact amplifier with a wide range of supply voltages, and its output power can be up to 20 watts. In order to ensure the stable operation of the LM1875, it needs to provide the required supply voltage and current. A voltage regulator is a common circuit component that can stabilize the input voltage at a low and stable level, providing reliable power for subsequent circuits.

The LM317 and LM337 are common positive and negative regulators that provide adjustable output voltages. If you want to power the LM1875 with the LM317 and LM337 regulated, this is theoretically possible. With proper circuit design and the right component selection, you can stabilize the input voltage within the range required by the LM1875 and meet the output power requirements of the LM1875.

It is important to note that the use of the LM317 and LM337 regulators requires consideration of parameters such as their maximum input voltage and maximum output current to avoid issues such as short circuits or overloads. In addition, the voltage regulator itself will generate a certain temperature rise, so heat dissipation needs to be considered to keep the regulator within a safe temperature range.

In summary, if you can properly design and implement the regulated circuit and ensure that it meets the requirements of the LM1875, then it is feasible to use the LM317 and LM337 regulated power supply. However, if you do not have the relevant experience and expertise, it is recommended to seek the help of a professional or use another reliable power source.

The LM1875 can be powered using the LM317 LM337 regulator. The LM1875 is a single-chip amplifier that delivers 20 watts of power for consumer audio applications. It requires 2 positive and 2 negative supplies, each of which is 25V (or 30V) quietly, and provides a large amount of current between them.

The LM317 and LM337 are three-terminal adjustable regulators that can adjust the output voltage range with two resistors and are used as positive power insights and negative power supplies, respectively. Since the LM1875 generates a certain amount of noise and clutter during operation, an external finger tremor power supply filter capacitor is required to reduce these noises. In addition, the appropriate heat sink needs to be selected to ensure that the LM1875 can operate within a safe temperature range.

In conclusion, it is feasible to use the LM317 LM337 regulator to power the LM1875, but it requires a reasonable circuit design and attention to safety issues.

LM1875 is a high-performance audio power amplifier IC with the advantages of low distortion and low noise, which is widely used in audio equipment. When using the LM1875, it is necessary to provide both positive and negative power supplies for power supply. At the same time, in order to ensure the stability of the power supply, a voltage regulator can be used for voltage regulation.

The LM317 and LM337 are two commonly used voltage regulators that provide accurate output voltages and have features such as overload protection. Both regulators can be used to supply the LM1875 with macro voltage regulation.

However, it should be noted that the quiescent current of LM1875 itself is large, about 60mA, and there will be a large dynamic current when working at high power. Therefore, when using a voltage regulator for voltage regulation, it is necessary to consider the issue of current capacity and select an appropriate voltage regulator.

In general, it is feasible to use LM317 and LM337 voltage regulation to supply power to LM1875, but it is necessary to select the appropriate voltage regulator according to the specific situation, and pay attention to the design and layout of the circuit to ensure the stability of the power supply and the reliable operation of the circuit.