LM2931, NCV2931 Series

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9

Figure 17. Fixed Output Regulator

Figure 18. Adjustable Output Regulator

Figure 19. (5.0 A) Low Differential

Voltage Regulator

Figure 20. Current Boost Regulator with

Short Circuit Projection

Figure 21. Constant Intensity Lamp Flasher

Input

Output

GND

0.1

LM2931−5.0

Fixed

Output

Switch Position 1 = Output On", 2 = Output Off"

LM2931C

Adjustable

Output

0.1

Output

Input

51 k

1

2

Output

Inhibit

Adjust

GND

The LM2931 series can be current boosted with a PNP transistor. The

D45VH7, on a heatsink, will provide an output current of 5.0 A with an input

to output voltage differential of approximately 1.0 V. Resistor R in

begins conducting. This circuit is not short circuit proof.

Input

≥ 6.0 V

D45VH7

5.0 V @ 5.0 A

Output

100

+

100

+

68

LM2931−5.0

LM2931C

Input

6.4 V to 30 V

2.0 k

8.2 k

100

+

CM

#345

100

+

33 k

6.2 V

0

22.5 k

w

R

1

R

2

R

1 )

R

2

Vout + Vref 1 )

R

2

R

1

) I

Adj

R

2

R

The circuit of Figure 19 can be modified to provide supply protection against

transistor. The current sensing PNP must be capable of handling the short

circuit current of the LM2931. Safe operating area of both transistors must be

considered under worst case conditions.

Input

R

Output

LM2931−5.0

100

100

++