Datasheet

Applications information L78MxxAB - L78MxxAC
18/29
Note: The circuit of Figure 19 can be modified to provide supply protection against short circuits by
adding a short-circuit sense resistor, R
SC
, and an additional PNP transistor. The current
sensing PNP must be able to handle the short-circuit current of the three-terminal regulator.
Therefore, a four-ampere plastic power transistor is specified.
Figure 19. Current boost regulator
I
O
= I
REG
+ Q
1
(I
REG
______)
V
BEQ1
R
1
R
1
= ______________
V
BEQ1
I
REQ
-(I
Q1
/β
Q1
)
Figure 20. Short-circuit protection