What is a LM7805 IC?
A LM7805 IC is a voltage regulator that outputs +5 volts.
An easy way to remember the voltage output by a LM78XX series of voltage regulators is the last two digits of the number. A LM7805 ends with "05"; thus, it outputs 5 volts. The "78" part is just the convention that the chip makers use to denote the series of regulators that output positive voltage. The other series of regulators, the LM79XX, is the series that outputs negative voltage. So:
An easy way to remember the voltage output by a LM78XX series of voltage regulators is the last two digits of the number. A LM7805 ends with "05"; thus, it outputs 5 volts. The "78" part is just the convention that the chip makers use to denote the series of regulators that output positive voltage. The other series of regulators, the LM79XX, is the series that outputs negative voltage. So:
LM78XX: Voltage regulators that output positive voltage, "XX"=voltage output.
LM79XX: Voltage regulators that output negative voltage, "XX"=voltage output.
LM79XX: Voltage regulators that output negative voltage, "XX"=voltage output.
Tabular Pin Information.
Problems with LM7805 IC.
7805 is not very efficient and has drop-out voltage problems. A lot of energy is wasted in the form of heat. If you are going to be using a heatsink, better calculate the heatsink size properly. The below formula should help in determining appropriate heatsink size for such applications.
Heat generated = (input voltage – 5) x output current.
If we have a system with input 15 volts and output current required is .5 amperes, we have: (15 – 5) x 0.5 = 10×0.5 =5W;
5W energy is being wasted as heat, hence an appropriate heatsink is required to disperse this heat. On the other hand, energy actually being used is: (5 x 0.5Amp) = 2.5W.
So twice the energy, that is actually utilized is wasted. On the other hand, if 9V is given as input at the same amount of load: (9-5) x 0.5 = 2W.
2W energy will be wasted as heat.
5W energy is being wasted as heat, hence an appropriate heatsink is required to disperse this heat. On the other hand, energy actually being used is: (5 x 0.5Amp) = 2.5W.
So twice the energy, that is actually utilized is wasted. On the other hand, if 9V is given as input at the same amount of load: (9-5) x 0.5 = 2W.
2W energy will be wasted as heat.
What we learn: Higher the input voltage, less efficient your 7805 will be.
Applications of the IC.
7805 IC is used in a wide range of circuits. The major ones being:
· Fixed-Output Regulator
· Positive Regulator in Negative Configuration
· Adjustable Output Regulator
· Current Regulator
· Adjustable DC Voltage Regulator
· Regulated Dual-Supply
· Output Polarity-Reversal-Protection Circuit
· Reverse bias projection Circuit
7805 IC also finds usage in building circuits for inductance meter, phone charger, portable CD player, infrared remote control extension and UPS power supply circuits.
· Fixed-Output Regulator
· Positive Regulator in Negative Configuration
· Adjustable Output Regulator
· Current Regulator
· Adjustable DC Voltage Regulator
· Regulated Dual-Supply
· Output Polarity-Reversal-Protection Circuit
· Reverse bias projection Circuit
7805 IC also finds usage in building circuits for inductance meter, phone charger, portable CD player, infrared remote control extension and UPS power supply circuits.
Click Below to see what a LM7805 looks like!
Thank You!
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