Rêyên Danûnê 7805

Hemî berekên deng nayê destûr bibin da ku bi heman dengê derbas bidekan ji ber çalkirina ên di serkirinan de. Ji bo wereyekirina dengê pêk ve û têk, regulatorên deng hatine werin. circuits anîn yên bikar an ji bo wereyekirina deng bi navan in regulator ICs. Lîstere, divê mîna IC 7805 biafirînin.

IC regulator 7805 ya wê ya yekember a xebatên 78xx ya regulator ICs e. Ev yek linear regulator deng fix e. Xeyal bike 78xx li ser 78xx wekî nivîs dengê fix e ku wekî jî tiştekê dengê fix e. Ji bo IC 7805, ev +5V DC regulated power supply e. Ev IC ya regulator dê ji bo hevsanekî şansekeşî têne. Dengê input ji bo bu IC dikare her dem tê be 35V, û bu IC dikare her dem 5V constant bide ji bo her dem input tê ne 35V.

PIN 1-INPUT
Funksiyonê ya pinê ya vê ye ku dengê input bidin. Divê li ser raya 7V derket 35V be. Unregulated voltage ji bo regulation ên bi ser pin ên apply bikin. Ji bo 7.2V input, PIN efeksiya herî mezin dibin.

PIN 2-GROUND
Ground bi ser pin ên connect bikin. Ji bo output û input, pin ên yekî neutral (0V) e.

PIN 3-OUTPUT
Pin ên bi ser vê pin ên bikar an ji bo regulated output. Ev dibit

Heat Dissipation in IC 7805

Di IC 7805 voltage regulator de, zorî energi bi rêjeya cûrê hilkiyekirin. Ferq li ser nivîsa dengê input û output bi cûrê hilkiyekirin. Demê, ji ber ferqa yekbûyî dengê input û output, zorî cûrê hilkiyekirin dibit. Bi tenê heat sink, zorî cûrê hilkiyekirin dikare malfunction bigire.

We call, the bare minimum tolerable difference between the input and output voltage to keep the output voltage at the proper level as dropout voltage. It is better to keep the input voltage 2 to 3V greater than the output voltage, or a suitable heat sink should be placed to dissipate excess heat. We have to calculate the heat sink size properly. The following formula will give an idea of this calculation.

Now, we can analyze the relation of generated heat and the input voltage value in this regulator with the following two examples.

Assume a system with input voltage 16V and required output current be 0.5A.
So, heat generated
Thus, 5.5W heat energy is wasted and the actual energy used
That is almost double energy is wasted as heat.
Next, we can consider the case when input is lower, say 9V.
In this case, heat generated
From this, we can conclude that for high input voltage, this regulator IC will become highly inefficient. If you’d like to learn more, we have a large range of free digital electronics MCQ questions.

Internal Block Diagram of 7805 Voltage Regulator

The internal block diagram of IC 7805 is represented in the figure below:

The block diagram comprises of an error amplifier, series pass element, current generator, reference voltage, current generator, starting circuit, SOA protection and thermal protection.

Here the operating amplifier performs as an error amplifier. The Zener diode is used for giving the reference voltage. It is shown below.

Transistor is the series pass element here. It is used for dissipating additional energy in the form of heat. It controls the output voltage by controlling the current among the input and output. SOA is the Safe Operating Area. It is in fact the conditions of voltage and current in which the equipment is expected to work without any self-damage. Here for the SOA protection, bipolar transistor is implemented with a series resistor and an auxiliary transistor. Heat sink is implemented for thermal protection when there is high supply voltage.

Regulated Power Supply Circuit

The voltage regulator 7805 and the other components are arranged in the circuit as shown in figure.

The purposes of coupling the components to the IC7805 are explained below.
C1– It is the bypass capacitor, used to bypass very small extent spikes to the earth.
C2 and C3– They are the filter capacitors. C2 is used to make the slow changes in the input voltage given to the circuit to the steady form. C3 is used to make the slow changes in the output voltage from the regulator in the circuit to the steady form. When the value of these capacitors increases, stabilization is enlarged. But these capacitors single-handedly are unable to filter the very minute changes in the input and output voltages.
C4– like C1, it is also a bypass capacitor, used to bypass very small extent spikes to the ground or earth. This is done without influencing other components.

Applications of Voltage Regulator 7805 IC