MPC5565 Просмотр технического описания (PDF) - Freescale Semiconductor

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MPC5565

Microcontroller

Freescale Semiconductor 

Electrical Characteristics

When powering down, VRC33 and VDDSYN have no delta requirement to each other, because the bypass

capacitors internal and external to the device are already charged. When not powering up or down, no delta

between VRC33 and VDDSYN is required for the VRC to operate within specification.

There are no power up/down sequencing requirements to prevent issues such as latch-up, excessive current

spikes, and so on. Therefore, the state of the I/O pins during power up and power down varies depending

on which supplies are powered.

Table 7 gives the pin state for the sequence cases for all pins with pad type pad_fc (fast type).

Table 7. Pin Status for Fast Pads During the Power Sequence

VDDE

Low

VDDE

VDDE

VDDE

VDDE

VDDE

VDD33

—

Low

Low

VDD33

VDD33

VDD33

VDD

POR

— Asserted

Low Asserted

VDD Asserted

Low Asserted

VDD Asserted

VDD Negated

Pin Status for Fast Pad Output Driver

pad_fc (fast)

Low

High

High

High impedance (Hi-Z)

Hi-Z

Functional

Table 8 gives the pin state for the sequence cases for all pins with pad type pad_mh (medium type) and

pad_sh (slow type).

Table 8. Pin Status for Medium and Slow Pads During the Power Sequence

VDDEH VDD

POR

Low

— Asserted

VDDEH Low Asserted

VDDEH VDD Asserted

VDDEH VDD Negated

Pin Status for Medium and Slow Pad Output Driver

pad_mh (medium) pad_sh (slow)

Low

High impedance (Hi-Z)

Hi-Z

Functional

The values in Table 7 and Table 8 do not include the effect of the weak-pull devices on the output pins

during power up.

Before exiting the internal POR state, the pins go to a high-impedance state until POR negates. When the

internal POR negates, the functional state of the signal during reset applies and the weak-pull devices

(up or down) are enabled as defined in the device reference manual. If VDD is too low to correctly

propagate the logic signals, the weak-pull devices can pull the signals to VDDE and VDDEH.

To avoid this condition, minimize the ramp time of the VDD supply to a time period less than the time

required to enable the external circuitry connected to the device outputs.

MPC5565 Microcontroller Data Sheet, Rev. 2.0

Freescale Semiconductor

11

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