The Role of TIP32C in Regulating Voltage Circuit

An integrated regulator is an integrated circuit that converts an unstable DC voltage into a stable DC voltage. Due to the obvious advantages of high voltage regulator, stable and reliable operation, simple peripheral circuit, small size and light weight, integrated regulator has been widely used in various power supply circuits. Commonly used integrated regulators are: metal round package, metal diamond package, plastic package, plastic package with radiator plate, flat package, double-line in-line package, etc. Three-terminal fixed output regulator is widely used in electronic systems.
The integrated regulator can be divided into three categories: series regulator, parallel regulator and on-off regulator. Figure 2 shows the internal circuit diagram of the most widely used series integrated regulator. The working principle is that the sampling circuit takes out the output voltage Uo proportionally, feeds it into the comparison amplifier to compare with the reference voltage, and after the difference is enlarged, controls the adjustment tube to keep the output voltage Uo stable.

78xx series integrated regulator is a common integrated regulator with fixed positive output voltage. The output voltage has specifications of 5V, 6V, 9V, 12V, 15V, 18V, 24V, and the output current is 1.5A. It has current limiting protection, overheat protection and overvoltage protection circuit inside. It uses a reference voltage source with low noise and small temperature drift, and works stably and reliably. 78xx series integrated regulator is a three-terminal device: 1 foot for input, 2 foot for ground, and 3 foot for output. It is very convenient to use.

The following figure shows an application circuit to increase the output voltage. The voltage regulator VD1 is connected in series between the two legs of the 78xx regulator and the ground, which can increase the output voltage Uo to a certain extent. The output voltage Uo is the sum of the output voltage of the 78xx regulator and the voltage regulator VC1 regulator value. VD2 is an output protection diode. Once the output voltage is lower than the VD1 regulator value, VD2 conducts and bypasses the output current to protect the output level of 7800 regulator from damage.

Below is an application circuit whose output voltage can be adjusted within a certain range. Due to the role of R1, RP resistance network, the output voltage is increased, the increase depends on the ratio of RP to R1. By adjusting the potentiometer RP, the output voltage can be adjusted within a certain range. When RP=0, the output voltage Uo equals the output voltage of the 78xx regulator; As RP increases gradually, so does Uo.

The following figure shows an application circuit that enlarges the output current. The VT2 is an external diffuser and the VT1 is a push tube. The two are Darlington connections. R1 is the bias resistance. The output current of the circuit depends on the parameters of VT2.

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The following figure shows an application circuit to increase the input voltage. The input voltage of the 78xx regulator is 35V (7824 is 40V). When the input voltage is higher than this value, the circuit shown below can be used. The VT, R1 and VD form a pre-regulator circuit, which makes the voltage added to the input of the 7800 regulator constant at the VD stable value (ignoring the B-E junction voltage drop of the VT). The input voltage at the Ui end depends only on the withstand voltage of the VT.

The integrated regulator can also be used as a constant current source. The figure below shows a constant current source circuit consisting of a 78xx regulator whose constant current Io is equal to the ratio of the output voltage of the 78xx regulator to R1.

79xx series integrated voltage regulator is a common three-terminal integrated regulator with fixed negative output voltage. Besides negative input and output voltage, other parameters and features are the same as 78xx series integrated voltage regulator. The three pins of the 79xx series integrated regulator are: one foot for ground, two foot for input and three foot for output.
The application circuit of 79xx series integrated regulator is also simple. The following figure shows a regulator power supply circuit with output-5V DC voltage. IC uses integrated regulator 7905. Heat sink should be attached when output current is large.

A voltage regulator circuit with positive and negative symmetric output can be composed by using both 78xx and 79xx regulators. The following figure shows the ++5V regulator power supply circuit. IC1 uses a fixed positive output integrated regulator 7805, IC2 uses a fixed negative output integrated regulator 7905, and VD1, VD2 are protective diodes to prevent damage to the integrated regulator when one of the positive or negative input voltage is not connected.