NCP561 ON, NCP561 Datasheet - Page 8

• Manufacturer Part Number: NCP561
• Description: 150 mA CMOS Low Iq Low-Dropout Voltage Regulator
• Manufacturer: ON

Input
Enable
The NCP561 series can be current boosted with a PNP transis-
tor. Resistor R in conjunction with V
when the pass transistor begins conducting; this circuit is not
short circuit proof. Input/Output differential voltage minimum is
increased by V
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.
R
1.0 mF
Input
Figure 14. Current Boost Regulator
Q1
Figure 16. Delayed Turn−on
BE
R
of the pass resistor.
1.0 mF
1.0 mF
C
1
2
3
1
2
3
1
2
3
BE
of the PNP determines
5
4
5
4
5
4
1.0 mF
APPLICATION CIRCUITS
Output
1.0 mF
1.0 mF
Output
Output
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Input
NCP561
Q2
8
Input
A regulated output can be achieved with input voltages that
exceed the 6.0 V maximum rating of the NCP561 series with
the addition of a simple pre−regulator circuit. Care must be
taken to prevent Q1 from overheating when the regulated
output (V
Short circuit current limit is essentially set by the V
R1. I
R
Figure 17. Input Voltages Greater than 6.0 V
R1
R2
5.6 V
SC
= ((V
OUT
Figure 15. Current Boost Regulator
Q1
) is shorted to GND.
BEQ2
1.0 mF
R3
1.0 mF
with Short Circuit Limit
− ib * R2) / R1) + I
Q1
1
2
3
1
2
3
O(max) Regulator
5
4
BE
5
4
of Q2 and
1.0 mF
Output
Output
1.0 mF