NCP511

http://onsemi.com

9

0

3

100

2

120

40

160

Time (ms)

2

1

20

4

1

0

140

80

60

0

R = 1.0 M

W

C = 1.0

mF

R = 1.0 M

W

C = 0.1

mF

No Delay

3

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

5.6 V

0

100

120

40

160

Time (ms)

20

140

80

60

R = 1.0 M

W

C = 1.0

mF

R = 1.0 mW

C = 0.1

mF

No Delay

Figure 18. Current Boost Regulator

Figure 19. Current Boost Regulator

with Short Circuit Limit

Figure 20. Delayed Turn−on

Figure 21. Delayed Turn−on

Figure 22. Input Voltages Greater than 6.0 V

The NCP511 series can be current boosted with a PNP transis-

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 volt-

ages then the above schematic can be used. Resistor R, and

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

few values were chosen and the resulting delay can be seen in

Figure 21.

The graph shows the delay between the enable signal and

output turn−on for various resistor and capacitor values.

A regulated output can be achieved with input voltages that

exceed the 6.0 V maximum rating of the NCP511 series with

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

taken to prevent Q1 from overheating when the regulated

Q1

R

APPLICATION CIRCUITS