LM137, LM337-N

SNVS778E – MAY 1999 – REVISED JANUARY 2016

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Feature Description (continued)

LM137

Horizontal sensitivity, 20 ms/div

Figure 14. Output Drift (10-W Pulse for 100 ms)

7.4 Device Functional Modes

7.4.1 Protection Diodes

When external capacitors are used with any IC regulator, it is sometimes necessary to add protection diodes to

prevent the capacitors from discharging through low current points into the regulator. Most 10-

μF capacitors have

low enough internal series resistance to deliver 20-A spikes when shorted. Although the surge is short, there is

enough energy to damage parts of the IC.

When an output capacitor is connected to a negative output regulator and the input is shorted, the output

capacitor pulls current out of the output of the regulator. The current depends on the value of the capacitor, the

The bypass capacitor on the adjustment terminal can discharge through a low current junction. Discharge occurs

when either the input, or the output, is shorted. Figure 15 shows the placement of the protection diodes.

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