LM340 datasheet(14/33 Pages) TI1

14 / 33 page

LM340, LM340A, LM7805, LM7812, LM7815

SNOSBT0K – FEBRUARY 2000 – REVISED JULY 2016

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Product Folder Links: LM340 LM340A LM7805 LM7812 LM7815

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Application Information (continued)

Figure 16. Regulator Floating Ground

Figure 17. Transients

When a value for θ(H–A) is found, a heat sink must be selected that has a value that is less than or equal to this

number.

θ(H–A) is specified numerically by the heat sink manufacturer in this catalog or shown in a curve that plots

temperature rise vs power dissipation for the heat sink.

8.2 Typical Applications

8.2.1 Fixed Output Voltage Regulator

The LM340x and LM78xx devices are primarily designed to provide fixed output voltage regulation. The simplest

implementation of LM340x and LM78xx is shown in Figure 18.

*Required if the regulator is located far from the power supply filter.

**Although no output capacitor is needed for stability, it does help transient response. (If needed, use 0.1-μF, ceramic

disc).

Figure 18. Fixed Output Voltage Regulator

8.2.1.1 Design Requirements

The device component count is very minimal. Although not required, TI recommends employing bypass

capacitors at the output for optimum stability and transient response. These capacitors must be placed as close

as possible to the regulator. If the device is located more than 6 inches from the power supply filter, it is required

to employ input capacitor.

LM340 Datasheet(PDF) 14 Page - Texas Instruments