LM7805CT View Datasheet(PDF) - International Cmos Technology

Part Name

Description

Manufacturer

LM7805CT

3-Terminal Positive Regulators

International Cmos Technology 

Line Regulation

140AK-5.0, IOUT = 1A, TA = 25˚C

Line Regulation

140AK-5.0, VIN = 10V, TA = 25˚C

Equivalent Schematic

00778105

00778106

Application Hints

The LM340/LM78XX series is designed with thermal protec-

tion, output short-circuit protection and output transistor safe

area protection. However, as with any IC regulator, it be-

comes necessary to take precautions to assure that the

regulator is not inadvertently damaged. The following de-

scribes possible misapplications and methods to prevent

damage to the regulator.

Shorting the Regulator Input: When using large capacitors

at the output of these regulators, a protection diode con-

nected input to output (Figure 1) may be required if the input

is shorted to ground. Without the protection diode, an input

short will cause the input to rapidly approach ground poten-

00778107

tial, while the output remains near the initial VOUTbecause of

the stored charge in the large output capacitor. The capacitor

will then discharge through a large internal input to output

diode and parasitic transistors. If the energy released by the

capacitor is large enough, this diode, low current metal and

the regulator will be destroyed. The fast diode in Figure 1 will

shunt most of the capacitors discharge current around the

regulator. Generally no protection diode is required for val-

ues of output capacitance ≤ 10 µF.

Raising the Output Voltage above the Input Voltage:

Since the output of the device does not sink current, forcing

the output high can cause damage to internal low current

paths in a manner similar to that just described in the “Short-

ing the Regulator Input” section.

9

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