LM317-N-MIL Datasheet, PDF (15/39 Pages) Texas Instruments – Wide Temperature Three-Pin Adjustable Regulator

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LM317-N-MIL
SNVSAY0 – JUNE 2017
Typical Applications (continued)
8.2.1.3 Application Curve
As shown in Figure 19, V_OUT will rise with V_IN minus some dropout voltage. This dropout voltage during startup
will vary with R_OUT.
Figure 19. V_OUT vs V_IN, V_OUT = 5V
8.2.2 5-V Logic Regulator With Electronic Shutdown
Figure 20 shows a variation of the 5-V output regulator application uses the device along with an NPN transistor
to provide shutdown control. The NPN will either block or sink the current from the ADJ pin by responding to the
TTL pin logic. When TTL is pulled high, the NPN is on and pulls the ADJ pin to GND, and the LM117 outputs
about
1.25 V. When TTL is pulled low, the NPN is off and the regulator outputs according to the programmed
adjustable voltage.
NOTE: Min. output ≊ 1.2 V
Figure 20. 5-V Logic Regulator With Electronic Shutdown
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