LPC802 datasheet(66/83 Pages) NXP

66 / 83 page

LPC802

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Product data sheet

Rev. 1.6 — 27 April 2018

66 of 83

NXP Semiconductors

LPC802

32-bit ARM Cortex-M0+ microcontroller

15.3 I/O power consumption

I/O pins are contributing to the overall dynamic and static power consumption of the part.

If pins are configured as digital inputs, a static current can flow depending on the voltage

level at the pin and the setting of the internal pull-up and pull-down resistors. This current

can be calculated using the parameters Rpu and Rpd given in Table 14 for a given input

voltage VI. For pins set to output, the current drive strength is given by parameters IOH and

IOL in Table 14, but for calculating the total static current, you also need to consider any

external loads connected to the pin.

I/O pins also contribute to the dynamic power consumption when the pins are switching

because the VDD supply provides the current to charge and discharge all internal and

external capacitive loads connected to the pin in addition to powering the I/O circuitry.

The contribution from the I/O switching current Isw can be calculated as follows for any

given switching frequency fsw if the external capacitive load (Cext) is known (see Table 14

for the internal I/O capacitance):

Isw = VDD x fsw x (Cio + Cext)

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