MC56F8345 Freescale Semiconductor, Inc, MC56F8345 Datasheet - Page 157

• Manufacturer Part Number: MC56F8345
• Description: 56f8300 16-bit Digital Signal Controllers
• Manufacturer: Freescale Semiconductor, Inc

Power due to capacitive loading on output pins is (first order) a function of the capacitive load and
frequency at which the outputs change.
in the IO cells as a function of capacitive load. In these cases:
Total Power = Σ((Intercept +Slope*Cload)*frequency/10MHz)
where:
Because of the low duty cycle on most device pins, power dissipation due to capacitive loads was found
to be fairly low when averaged over a period of time.
E, the external [static component], reflects the effects of placing resistive loads on the outputs of the
device. Sum the total of all V
0.5 for the purposes of these rough calculations. For instance, if there is a total of eight PWM outputs
driving 10mA into LEDs, then P = 8*.5*.01 = 40mW.
In previous discussions, power consumption due to parasitics associated with pure input pins is ignored,
as it is assumed to be negligible.
Freescale Semiconductor
Preliminary
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•
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Summation is performed over all output pins with capacitive loads
Total Power is expressed in mW
Cload is expressed in pF
Table 10-24 IO Loading Coefficients at 10MHz
PDU08DGZ_ME
PDU04DGZ_ME
2
/R or IV to arrive at the resistive load contribution to power. Assume V =
56F8345 Technical Data, Rev. 17
Table 10-24
provides coefficients for calculating power dissipated
Intercept
1.15mW
1.3
0.11mW / pF
0.11mW / pF
Slope
Power Consumption
157