MC33389 데이터 시트보기 (PDF) - Motorola => Freescale

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MC33389

System Basis Chip with Low Speed Fault Tolerant CAN

Motorola => Freescale 

MC33389

FreescalDeEVSICEeDmESiCcRoIPnTIOdNuctor, Inc.

Thermal Management

The MC33389 is proposed in two different packages.

HSOP20 for high power applications and SO28WB with 8 pins

to the leadframe for medium power applications.

SO28WB Package

The case(pin) to junction Rth is here represented by only

one thermal resistance for the total power since the 3 power

sources strongly interact on the silicon for such a package.

HSOP20 Package

For such a package, the heat flow is mainly vertical and

each heat source (dissipating element) can be seen as an

independent thermal resistance to the Heatsink. The thermal

network can be roughly depicted as:

Figure 2. HSOP20 Simplified Thermal Model

V1 power

V2 power

Can power

Tj (max 155°C)

Figure 3. SO28WB Simplified Thermal Model

Total power

Tj (max 155°C)

Rthj/c=20°C/W

9°C/W

6.5°C/W

Rthj/c=18°C/W

Tcase(pin)

Tcase(heatsink)

Rthc/a

Rthc/a (ECU supplier dependent)

Tambient

Tambient

Example

Assuming IV1=100mA at Vbat=16V,

IV2=150mA at Vbat=16V (Excluding CAN consumption).

ICAN=50mA at Vbat=16V, we have :

PV1=1.1W, PV2=1.65W, Pcan=0.55W

System assumptions:

If Tamb=85°C and Rthc/a=18°C/W, this gives:

Tcase=Tamb+Rth c/a x 3.3W = 85+18 x 3.3=145°C

and TjV1=TjV2=Tjcan=155°C.

This example represents the limit for the maximum power

dissipations with a HSOP20.

Example

Assuming IV1=45mA at Vbat=16V,

IV2=45mA at Vbat=16V (Excluding CAN consumption).

ICAN=50mA at Vbat=16V, we have :

PV1=0.5W, PV2=0.5W, Pcan=0.55W thus Ptotal=1.55W

System assumptions:

If Tamb=85°C and Rthc/a=25°C/W, this gives:

Tcase=Tamb+Rthc/a x 1.55W=85+25x1.55 =124°C

and TjV1=124 + 20 x 1.55= 155°C.

This example represents the limit for the maximum power

dissipations with a SO28WB.

For More Information On This Product,

MC33389

Go toM: wOTwOwR.OfrLeAescale.com

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