LM317SSLASHNOPB datasheet(18/51 Pages) TI

Part #	LM317S/NOPB

Description	LM117, LM317-N Wide Temperature Three-Pin Adjustable Regulator

PDF	51 Pages

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Manufacturer	TI [Texas Instruments]

Direct Link	http://www.ti.com

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18 / 51 page

LM117

LM117, LM317-N

SNVS774Q – MAY 2004 – REVISED JUNE 2020

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Product Folder Links: LM117 LM317-N

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Typical Applications (continued)

9.2.3 Slow Turnon 15-V Regulator

An application of LM117 includes a PNP transistor with a capacitor to implement slow turnon functionality (see

Figure 21). As VIN rises, the PNP sinks current from the ADJ rail. The output voltage at start up is the addition of

the 1.25-V reference plus the drop across the base to emitter. While this is happening, the capacitor begins to

charge and eventually opens the PNP. At this point, the device functions normally, regulating the output at 15 V.

A diode is placed between C1 and VOUT to provide a path for the capacitor to discharge. Such controlled turnon

is useful for limiting the in-rush current.

Figure 21. Slow Turnon 15-V Regulator

LM317S/NOPB Datasheet(PDF) 18 Page - Texas Instruments