LM117HV, LM317HV

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SNVS773D – APRIL 2000 – REVISED SEPTEMBER 2015

Typical Applications (continued)

9.2.1.2 Detailed Design Procedure

The output voltage is set based on the selection of the two resistors, R1 and R2, as shown in Figure 16. For

details on capacitor selection, refer to External Capacitors.

9.2.1.3 Application Curve

As shown in Figure 17, the maximum output current capability is limited by the input-output voltage differential,

package type, and junction temperature.

Figure 17. Current Limit

9.2.2 Digitally Selected Outputs

Figure 18 shows a digitally selectable output voltage. In its default state, all transistors are off and the output

voltage is set based on R1 and R2. By driving certain transistors, the associated resistor is connected in parallel

to R2, modifying the output voltage of the regulator.

*Sets maximum VOUT

Figure 18. Digitally Selected Outputs

9.2.3 Logic Regulator (5-V) With Electronic Shutdown

A variation of the 5-V output regulator application uses the LM117HV 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 LM117HV outputs about

1.25 V. When TTL is pulled low, the NPN is off and the regulator outputs according to the programmed

adjustable voltage.

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