NCP565 ON, NCP565 Datasheet - Page 9

• Manufacturer Part Number: NCP565
• Description: 1.5 A Low Dropout Linear Regulator
• Manufacturer: ON

Protection Diodes
regulator it is sometimes necessary to add protection diodes.
If the input voltage of the regulator gets shorted, the output
capacitor will discharge into the output of the regulator. The
discharge current depends on the value of the capacitor, the
output voltage and the rate at which V
NCP565 linear regulator, the discharge path is through a
large junction and protection diodes are not usually needed.
If the regulator is used with large values of output
capacitance and the input voltage is instantaneously shorted
to ground, damage can occur. In this case, a diode connected
as shown in Figure 20 is recommended.
When large external capacitors are used with a linear
V
Figure 20. Protection Diode for Large
in
C
1
V
GND
in
Output Capacitors
1N4002 (Optional)
NCP565
V
Adj
out
C
80
70
60
50
40
30
Adj
0
Thermal Resistance and Maximum Power
R
R
1
2
in
Vertically
Mounted
Figure 21. 3−Pin and 5−Pin D
Free Air
5.0
drops. In the
Dissipation vs. P.C.B Length
C
V
out
2
L, LENGTH OF COPPER (mm)
http://onsemi.com
10
Minimum
Size Pad
NCP565
R
15
9
qJA
P
D(max)
Thermal Considerations
that is designed to protect the regulator in the event that the
maximum junction temperature is exceeded. This feature
provides protection from a catastrophic device failure due to
accidental overheating. It is not intended to be used as a
substitute for proper heat sinking. The maximum device
power dissipation can be calculated by:
package. The package has an exposed metal tab that is
specifically designed to reduce the junction to air thermal
resistance, R
copper as a heat dissipater. Figure 21 shows typical R
values that can be obtained from a square pattern using
economical single sided 2.0 ounce copper board material.
The final product thermal limits should be tested and
quantified in order to insure acceptable performance and
reliability. The actual R
graph shown. This will be due to any changes made in the
copper aspect ratio of the final layout, adjacent heat sources,
and air flow.
This series contains an internal thermal limiting circuit
The devices are available in surface mount D
for T
20
A
= +50 C
L
Î Î Î Î
Î Î Î Î
Î Î Î Î
Î Î Î Î
2
2.0 oz. Copper
PAK
qJA
25
L
, by utilizing the printed circuit board
P D +
30
3.5
3.0
2.5
2.0
1.5
1.0
qJA
T J(max) * T A
can vary considerably from the
R qJA
2
PAK
qJA