LM317SSLASHNOPB datasheet(17/48 Pages) TI1

Part #	LM317S/NOPB

Description	Wide Temperature Three-Pin Adjustable Regulator

PDF	48 Pages

Scroll/Zoom	100%

Manufacturer	TI1 [Texas Instruments]

Direct Link	http://www.ti.com

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17 / 48 page

LM117

LM117, LM317-N

www.ti.com

SNVS774P – MAY 2004 – REVISED OCTOBER 2015

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

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LM317S/NOPB Datasheet(PDF) 17 Page - Texas Instruments