LM317L 데이터 시트보기 (PDF) - ON Semiconductor

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LM317L

LOW CURRENT THREE-TERMINAL ADJUSTABLE POSITIVE VOLTAGE REGULATOR

ON Semiconductor 

LM317L, NCV317LB

Protection Diodes

When external capacitors are used with any IC regulator

it is sometimes necessary to add protection diodes to prevent

the capacitors from discharging through low current points

into the regulator.

Figure 14 shows the LM317L with the recommended

protection diodes for output voltages in excess of 25 V or

high capacitance values (CO > 10 mF, CAdj > 5.0 mF). Diode

D1 prevents CO from discharging thru the IC during an input

short circuit. Diode D2 protects against capacitor CAdj

discharging through the IC during an output short circuit.

The combination of diodes D1 and D2 prevents CAdj from

discharging through the IC during an input short circuit.

+25V

Vout R1

VO

IO

LM317L

Vin

1.25k

Adjust

* To provide current limiting of IO

ăĂto the system ground, the source of

ăĂthe current limiting diode must be tied to

ăĂa negative voltage below - 7.25 V.

R2 ≥

Vref

IDSS

R1 =

Vref

IOmax + IDSS

VO < POV + 1.25 V + VSS

ILmin - IP < IO < 100 mA - IP

As shown O < IO < 95 mA

D1

R2

1N914

500

D2

1N914

1N5314

VSS*

Figure 20. Adjustable Current Limiter

D1

1N4002

Vin

Vout

LM317L

+

Cin

R1

D2

CO

Adjust

1N4002

R2

CAdj

Figure 19. Voltage Regulator with

Protection Diodes

D1

1N4002

Vin

Vout

LM317L

+

120

1.0mF

Adjust

720

MPS2222

1.0k

TTL

Control

Minimum Vout = 1.25 V

D1 protects the device during an input short circuit.

Figure 21. 5.0 V Electronic Shutdown Regulator

Vin

Vout

LM317L

240

1N4002

Adjust

R2

50k

MPS2907

+

10mF

Figure 22. Slow Turn-On Regulator

Iout

Vin

R1

R2

LM317L

Vout

Adjust

IAdj

Ioutmax =

Ioutmax =

Vref

R1

1.25 V

+ IAdj ^ R1

Vref

R1 + R2

1.25 V

+ IAdj ^ R1 + R2

5.0 mA < Iout < 100 mA

Figure 23. Current Regulator

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