NCP565/NCV565

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11

Protection Diodes

When large external capacitors are used with a linear

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

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 23 is recommended.

NCP565

GND

Adj

1N4002 (Optional)

Figure 23. Protection Diode for Large

Output Capacitors

Thermal Considerations

This series contains an internal thermal limiting circuit

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:

PD +

TJ(max) * TA

R

qJA

Figure 24. Thermal Resistance

0

50

100 150

200 250

300 350 400

450 500

40

60

80

100

120

140

160

180

COPPER HEAT−SPREADER AREA (mm sq)

200

DFN 1 oz Cu

DFN 2 oz Cu

SOT−223 1 oz Cu

SOT−223 2 oz Cu