JAJSBC2L March 2000 – January 2018 LM317L-N
PRODUCTION DATA.
An application of LM317L-N includes a PNP transistor with a capacitor to implement slow turnon functionality (see Figure 22). 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.