ISL9N7030BLP3 Datasheet(数据表) 6 Page

6 page

ISL9N7030BLP3, ISL9N7030BLS3ST Rev. B

Thermal Resistance vs. Mounting Pad Area

The maximum rated junction temperature, TJM, and the

thermal resistance of the heat dissipating path determines the

maximum allowable device power dissipation, PDM, in an

application. Therefore the application’s ambient temperature,

TA (

oC), and thermal resistance RθJA (oC/W) must be reviewed

to ensure that TJM is never exceeded. Equation 1

mathematically represents the relationship and serves as the

basis for establishing the rating of the part.

In using surface mount devices such as the TO-263

package, the environment in which it is applied will have a

significant influence on the part’s current and maximum

power dissipation ratings. Precise determination of PDM is

complex and influenced by many factors:

1. Mounting pad area onto which the device is attached and

whether there is copper on one side or both sides of the

board.

2. The number of copper layers and the thickness of the board.

3. The use of external heat sinks.

4. The use of thermal vias.

5. Air flow and board orientation.

6. For non steady state applications, the pulse width, the

duty cycle and the transient thermal response of the part,

the board and the environment they are in.

Fairchild provides thermal information to assist the

designer’s preliminary application evaluation. Figure 19

defines the RθJA for the device as a function of the top

copper (component side) area. This is for a horizontally

positioned FR-4 board with 1oz copper after 1000 seconds

of steady state power with no air flow. This graph provides

the necessary information for calculation of the steady state

junction temperature or power dissipation. Pulse applications

can be evaluated using the Fairchild device Spice thermal

model or manually utilizing the normalized maximum

transient thermal impedance curve.

Displayed on the curve are RθJA values listed in the Electrical

Specifications table. The points were chosen to depict the

compromise between the copper board area, the thermal

resistance and ultimately the power dissipation, PDM.

Thermal resistances corresponding to other copper areas can

be obtained from Figure 19 or by calculation using Equation 2.

RθJA is defined as the natural log of the area times a coefficient

added to a constant. The area, in square inches is the top

copper area including the gate and source pads.

FIGURE 17. SWITCHING TIME TEST CIRCUIT

FIGURE 18. SWITCHING TIME WAVEFORM

Test Circuits and Waveforms (Continued)

VGS

RGS

DUT

VDD

VDS

VGS

tON

td(ON)

90%

10%

VDS

90%

10%

td(OFF)

tOFF

90%

50%

10%

PULSE WIDTH

VGS

(EQ. 1)

–

()

ZθJA

-------------------------------

(EQ. 2)

RθJA

26.51

19.84

0.262

Area

()

----------------------------------------

110

0.1

RθJA = 26.51+ 19.84/(0.262+Area)

AREA, TOP COPPER AREA (in2)

FIGURE 19. THERMAL RESISTANCE vs MOUNTING PAD AREA

ISL9N7030BLP3, ISL9N7030BLS3ST

ISL9N7030BLP3 Datasheet(数据表) 6 Page - Fairchild Semiconductor

ISL9N7030BLP3 Datasheet(HTML) 6 Page - Fairchild Semiconductor

HTML 页

1 2 3 4 5 6 7 8 9 10

数据表下载

相关电子零件

链接网址