NCP566 ON Semiconductor, NCP566 Datasheet - Page 8

• Manufacturer Part Number: NCP566
• Description: Low Dropout Linear Regulator
• Manufacturer: ON Semiconductor

PCB Layout Considerations
good load transient performance. Because it is very sensitive
to its PCB layout, particular care has to be taken when
tackling Printed Circuit Board (PCB) layout. For
microprocessor applications it is customary to use an output
capacitor network consisting of several capacitors in
parallel. This reduces the overall ESR and reduces the
instantaneous output voltage drop under transient load
conditions. The output capacitor network should be as close
as possible to the load for the best results.
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
NCP566 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 18 is recommended.
Good PCB layout plays an important role in achieving
When large external capacitors are used with a linear
V
IN
C
Figure 18. Protection Diode for Large
IN
V
Output Capacitors
IN
1N4002 (Optional)
NCP566
GND
V
OUT
in
drops. In the
C
OUT
V
http://onsemi.com
OUT
NCP566
8
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:
This series contains an internal thermal limiting circuit
200
180
160
140
120
100
80
60
40
0
50 100 150
COPPER HEAT−SPREADER AREA (mm sq)
Figure 19. Thermal Resistance
P D +
T J(max) * T A
200 250 300 350 400 450 500
2 oz Cu
1 oz Cu
R qJA