NCP551, NCV551

http://onsemi.com

9

Output

R

1

2

3

5

4

Input

1.0 mF

1.0 mF

Output

1

2

3

5

4

Input

1.0 mF

1.0 mF

Q2

Q1

R3

R1

R2

Output

1

2

3

5

4

Input

1.0 mF

1.0 mF

Output

1

2

3

5

4

Enable

1.0 mF

1.0 mF

C

Output

1

2

3

5

4

Input

1.0 mF

1.0 mF

Q1

R

11 V

Figure 21. Current Boost Regulator

Figure 22. Current Boost Regulator with

Short Circuit Limit

Figure 23. Delayed Turn−on

Figure 24. Input Voltages Greater than 12 V

The NCP551 series can be current boosted with a PNP transist-

when the pass transistor begins conducting; this circuit is not

short circuit proof. Input/Output differential voltage minimum is

If a delayed turn−on is needed during power up of several

voltages then the above schematic can be used. Resistor R,

and capacitor C, will delay the turn−on of the bottom regulator.

A regulated output can be achieved with input voltages that

exceed the 12 V maximum rating of the NCP551 series with

the addition of a simple pre−regulator circuit. Care must be

taken to prevent Q1 from overheating when the regulated

Q1

R