MPC8250AVRIHBC Просмотр технического описания (PDF) - Freescale Semiconductor

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MPC8250AVRIHBC

MPC8250 Hardware Specifications

Freescale Semiconductor 

Electrical and Thermal Characteristics

1 The default configuration of the CPM pins (PA[0–31], PB[4–31], PC[0–31], PD[4–31]) is input. To prevent excessive

DC current, it is recommended to either pull unused pins to GND or VDDH, or to configure them as outputs.

2 The leakage current is measured for nominal VDD, VCCSYN, and VDD.

2.2 Thermal Characteristics

Table 4 describes thermal characteristics.

Table 4. Thermal Characteristics

Characteristic

Value

Symbol

Unit

480 TBGA

516 PBGA

Air Flow

Junction to ambient—

single-layer board 1

13

24

10

18

Natural convection

1 m/s

Junction to ambient—

θJA

11

16

°C/W

Natural convection

four-layer board

8

13

1 m/s

Junction to board 2

θJB

4

8

°C/W

—

Junction to case 3

θJC

1.1

6

°C/W

—

1 Assumes no thermal vias

2 Thermal resistance between the die and the printed circuit board per JEDEC JESD51-8. Board temperature is

measured on the top surface of the board near the package.

3 Thermal resistance between the die and the case top surface as measured by the cold plate method (MIL SPEC-883

Method 1012.1).

2.3 Power Considerations

The average chip-junction temperature, TJ, in °C can be obtained from the following:

TJ = TA + (PD x θJA)

(1)

where

TA = ambient temperature °C

θJA = package thermal resistance, junction to ambient, °C/W

PD = PINT + PI/O

PINT = IDD x VDD Watts (chip internal power)

PI/O = power dissipation on input and output pins (determined by user)

For most applications PI/O < 0.3 x PINT. If PI/O is neglected, an approximate relationship between PD and

TJ is the following:

PD = K/(TJ + 273° C)

(2)

Solving equations (1) and (2) for K gives:

K = PD x (TA + 273° C) + θJA x PD2

(3)

MPC8250 Hardware Specifications, Rev. 2

10

Freescale Semiconductor

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