MC9S08QE8_11 Datasheet, PDF(9/52 Page) Freescale Semiconductor, Inc – Up to 20 MHz CPU at 3.6 V to 1.8 V across temperature range of

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MC9S08QE8_11 Datasheet, PDF (9/52 Pages) Freescale Semiconductor, Inc – Up to 20 MHz CPU at 3.6 V to 1.8 V across temperature range of –40 °C to 85 °C

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Table 4. Thermal Characteristics

Rating

Operating temperature range

(packaged)

Maximum junction temperature

Thermal resistance

Single-layer board

32-pin QFN

32-pin LQFP

28-pin SOIC

20-pin SOIC

16-pin PDIP

16-pin TSSOP

Thermal resistance

Four-layer board

32-pin QFN

32-pin LQFP

28-pin SOIC

20-pin SOIC

16-pin PDIP

16-pin TSSOP

Symbol

TJM

ï±JA

Value

TL to TH

â40 to 85

110

108

ï±JA

Electrical Characteristics

Unit

ï°C

ï°C/W

The average chip-junction temperature (TJ) in ï°C can be obtained from:

TJ = TA + (PD ï´ ï±JA)

Eqn. 1

where:

TA = Ambient temperature, ï°C

ï±JA = Package thermal resistance, junction-to-ambient, ï°C/W

PD = Pint ï«ï PI/O

Pint = IDD ï´ VDD, Watts â chip internal power

PI/O = Power dissipation on input and output pins â user determined

For most applications, PI/O ï¼ï¼ Pint and can be neglected. An approximate relationship between PD and TJ

(if PI/O is neglected) is:

PD = K ï¸ (TJ + 273 ï°C)

Solving Equation 1 and Equation 2 for K gives:

Eqn. 2

K = PD ï´ (TA + 273 ï°C) + ï±JA ï´ (PD)2

Eqn. 3

MC9S08QE8 Series Data Sheet, Rev. 8

Freescale Semiconductor

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