7805 pin chart, Application Circuit

7805 Power Supply Circuit Diagram:

7805 pin chart

7805 typical application circuit diagram:

Shows the typical application circuit of the 78xx series Integrated Voltage Regulator. This is a regulated power supply circuit that outputs positive v dc voltage. IC uses an integrated voltage regulator 7805, c1 and c2 are the input and output filter capacitors, and RL is the load resistance. When the output power is large, 7805 should be equipped with a hot plate.

An Application Circuit Used to increase the output voltage. The voltage regulator vd1 is connected to the voltage regulator 78xx between two feet and the ground, which can improve the output voltage uo. The output voltage uo is the sum of the output voltage of the Voltage Regulator 78xx and the voltage regulator value of the Voltage Regulator diode vc1. Vd2 is the output protection diode. Once the output voltage is lower than the vd1 regulator value, vd2 is turned on and the output current is bypassed to protect the output level of the voltage regulator from being damaged.

It is an application circuit that can be adjusted within a certain range of output voltage. Due to the role of R1 and RP resistance networks, the output voltage is increased. The increase is determined by the ratio of RP to R1. Adjust the potentiometer RP to adjust the output voltage within a certain range. When Rp = 0, the output voltage uo is equal to the output voltage of the 78xx voltage regulator. When RP increases gradually, the uo increases gradually.

An Application Circuit Used to expand the output current. VT2 is the external Expansion Flow Rate tube, vt1 is the streamer tube, and the two are the dington connections. R1 is the offset resistance. The maximum output current of the circuit depends on the VT2 parameter.

 

An Application Circuit Used to increase the input voltage. The maximum input voltage of the 78xx voltage regulator is 35 V (7824 is 40 V). When the input voltage is higher than this value, the circuit shown in can be used. VT, R1, and VD constitute a pre-regulated circuit, so that the voltage added to the input of the Voltage Regulator of 7800 is constant at the voltage regulator value of VD (ignore the B-e junction Pressure Drop of VT ). The maximum input voltage of the UI depends only on the voltage of VT.

The integrated voltage regulator can also be used as a constant current source. For the constant current source circuit consisting of 78xx voltage regulator, its constant current IO is equal to the ratio of the output voltage of 78xx voltage regulator to R1.

The 79xx series integrated voltage regulator is a common three-end integrated voltage regulator with fixed negative output voltage. Apart from the negative input voltage and output voltage, other parameters and features are the same as those of the 78xx series integrated voltage regulator. The 79xx series integrated voltage regulator has three pins: one pin is the grounding end, two pins are the input end, and three pins are the output end.
The Application Circuit of the 79xx series integrated voltage regulator is also very simple. As shown in the following figure, the voltage regulator circuit is used for the output-5 v dc voltage. The IC uses an integrated voltage regulator of 7905. A hot plate should be used when the output current is large.

Both 78xx and 79xx voltage regulators can be used to form a voltage regulator circuit with positive and negative symmetric output. Shows the ± 5 V regulated power supply circuit, IC1 uses a fixed positive output integrated voltage regulator 7805, ic2 uses a fixed negative output integrated voltage regulator 7905, vd1, vd2 as the protection diode, it is used to prevent damage to the integrated voltage regulator when either positive or negative input voltage is not connected.