Motorola MC9S12DT128B, MC9S12DB128B manual The total power dissipation can be calculated from

MC9S12DT128B Device User Guide — V01.07

PD = Total Chip Power Dissipation, [W]

ΘJA = Package Thermal Resistance, [°C/W]

The total power dissipation can be calculated from:

PD = PINT + PIO

PINT = Chip Internal Power Dissipation, [W]

Two cases with internal voltage regulator enabled and disabled must be considered:

1. Internal Voltage Regulator disabled

PINT = IDD ⋅ VDD + IDDPLL ⋅ VDDPLL + IDDA ⋅ VDDA

P	IO	= ∑R	DSON	⋅ I	IO	2
						i
		i

Which is the sum of all output currents on I/O ports associated with VDDX and VDDM.

For RDSON is valid:			VOL
RDSON		=			;for outputs driven low
			------------IOL
respectively
	VDD5			–VOH
RDSON						;for outputs driven high
	= ------------------------------------		IOH

2. Internal voltage regulator enabled

PINT = IDDR ⋅ VDDR + IDDA ⋅ VDDA

IDDR is the current shown in Table A-7and not the overall current flowing into VDDR, which additionally contains the current flowing into the external loads with output high.

P	IO	= ∑R	DSON	⋅ I	IO	2
						i
		i

Which is the sum of all output currents on I/O ports associated with VDDX and VDDR.

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