33389 datasheet(21/49 Pages) FREESCALE

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Analog Integrated Circuit Device Data

Freescale Semiconductor

33389

FUNCTIONAL DEVICE OPERATION

Figure 6. HSOP-20 Simplified Thermal Model

Example

Assuming IV1 = 100 mA at VBAT = 16 V,

IV2 =150 mA at VBAT = 16 V (Excluding CAN

consumption).

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

PV1 = 1. 1 W, PV2 = 1.65 W, PCAN = 0.55 W

System assumptions:

If TAMB= 85°C and RTHC/A = 18°C/W, this gives:

TCASE = TAMB+RTHC/A x 3.3 W = 85 + 18 x 3.3 = 145°C

and TJV1 = TJV2 = TJCAN=155°C.

This example represents the limit for the maximum power

dissipation with a HSOP20.

SO28WB Package

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

one thermal resistance for the total power because the three

power sources strongly interact on the silicon for such a

package.

Figure 7. SO28WB Simplified Thermal Model

Example

Assuming IV1 = 45 mA at VBAT = 16 V,

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

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

PV1 = 0.5 W, PV2 =0.5 W, PCAN =0.55 W thus PTOTAL

=1.55W

System assumptions:

If TAMB = 85°C and RTHC/A = 25°C/W, this gives:

TCASE = TAMB + RTHC/A x 1.55 W = 85+25 x 1.55 = 124°C

and TJV1 = 124 + 20 x 1.55 = 155°C.

DIFFERENT DEVICE VERSIONS

The MC33389 is proposed in several package versions,

and also offers slight differences in term of functionalities.

The device version is identified in the device part number by

the first letter after the 389 number. The package

identification is done by the last two letters of the part number

(DW for SO28 wide body, DH for power SO20).

T ambient

T case (Heatsink)

V1 Power

V2 Power

CAN Power

TJ (Max 155°C)

RTHJ/C=18°C/W

6.5°C/W

9°C/W

RTHC/A (ECU supplier dependent)

TCASE (pin)

TJ (Max 155°C)

Total Power

RTHC/A

TAMBIENT

RTHJ/C = 20°C/W

33389 Datasheet(PDF) 21 Page - Freescale Semiconductor, Inc

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