LM317SSLASHNOPB datasheet(24/51 Pages) TI

24 / 51 page

LM117

Short circuit current is approximately

, or 210 mA

600

LM317-N

LM117, LM317-N

SNVS774Q – MAY 2004 – REVISED JUNE 2020

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Typical Applications (continued)

9.2.11 Current-Limited Voltage Regulator

A maximum limit on output current can be set using the circuit shown in Figure 29. The load current travels

through R3 and R4. As the load current increases, the voltage drop across R3 increases until the NPN transistor

is driven, during which the ADJ pin is pulled down to ground and the output voltage is pulled down to the

reference voltage of 1.25 V.

(Compared to LM117's higher current limit)

—At 50 mA output only ¾ volt of drop occurs in R3 and R4

Figure 29. Current-Limited Voltage Regulator

9.2.12 Adjusting Multiple On-Card Regulators With Single Control

Figure 30 shows how multiple LM117 regulators can be controlled by setting one resistor. Because each device

maintains the reference voltage of about 1.25 V between its VOUT and ADJ pins, we can connect each ADJ rail to

a single resistor, setting the same output voltage across all devices. This allows for independent outputs, each

responding to its corresponding input only. Designers must also consider that by the nature of the circuit,

changes to R1 and R2 will affect all regulators.

NOTE: *All outputs within ±100 mV

†Minimum load—10 mA

Figure 30. Adjusting Multiple On-Card Regulators With Single Control

LM317S/NOPB bảng dữ liệu(PDF) 24 Page - Texas Instruments