NCV8667 Ver la hoja de datos (PDF) - ON Semiconductor

Número de pieza

componentes Descripción

Fabricante

NCV8667

150 mA LDO Regulator with Enable, Reset and Early Warning

ON Semiconductor 

NCV8667

Thermal Considerations

As power in the NCV8667 increases, it might become

necessary to provide some thermal relief. The maximum

power dissipation supported by the device is dependent

upon board design and layout. Mounting pad configuration

on the PCB, the board material, and the ambient temperature

affect the rate of junction temperature rise for the part. When

the NCV8667 has good thermal conductivity through the

PCB, the junction temperature will be relatively low with

high power applications. The maximum dissipation the

NCV8667 can handle is given by:

ƪ ƫ TJ(MAX) * TA

PD(MAX) +

RqJA

(eq. 5)

Since TJ is not recommended to exceed 150°C, then the

NCV8667 soldered on 645 mm2, 1 oz copper area, FR4 can

dissipate up to 1.33 W when the ambient temperature (TA)

is 25°C. See Figure 29 for RthJA versus PCB area. The power

dissipated by the NCV8667 can be calculated from the

following equations:

PD [ VinǒIq@IoutǓ ) IoutǒVin * VoutǓ

(eq. 6)

or

PD(MAX) ) ǒVout

Vin(MAX) [

Iout ) Iq

IoutǓ

(eq. 7)

170

160

150

140

SO−8 1 oz

130

SO−8 2 oz

120

110

100

SO−14 1 oz

90

SO−14 2 oz

80

70

0 100 200 300 400 500 600 700

COPPER HEAT SPREADER AREA (mm2)

Figure 32. Thermal Resistance vs. PCB Copper Area

Hints

Vin and GND printed circuit board traces should be as

wide as possible. When the impedance of these traces is

high, there is a chance to pick up noise or cause the regulator

to malfunction. Place external components, especially the

output capacitor, as close as possible to the NCV8667 and

make traces as short as possible.

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