MCF5275LCVM133 Просмотр технического описания (PDF) - Freescale Semiconductor

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MCF5275LCVM133

Integrated Microprocessor Family Hardware Specification

Freescale Semiconductor 

Design Recommendations

analysis to separate traces with significant parallelism or are otherwise "noisy". Use 6 mils trace

and separation. Clocks get extra separation and more precise balancing.

5.2 Power Supply

• 33uF, 0.1 µF, and 0.01 µF across each power supply

5.2.1 Supply Voltage Sequencing and Separation Cautions

Figure 2 shows situations in sequencing the I/O VDD (OVDD), SDRAM VDD (SDVDD), PLL VDD

(PLLVDD), and Core VDD (VDD).

3.3V

2.5V

1.5V

1

Supplies Stable

OVDD, SDVDD

SDVDD (2.5V)

VDD, PLLVDD

2

0

Notes:

1. VDD should not exceed OVDD, SDVDD or PLLVDD by more than

0.4 V at any time, including power-up.

Time

2. Recommended that VDD/PLLVDD should track OVDD/SDVDD up to

0.9 V, then separate for completion of ramps.

3. Input voltage must not be greater than the supply voltage (OVDD, SDVDD,

VDD, or PLLVDD) by more than 0.5 V at any time, including during power-up.

4. Use 1 ms or slower rise time for all supplies.

Figure 2. Supply Voltage Sequencing and Separation Cautions

The relationship between SDVDD and OVDD is non-critical during power-up and power-down sequences.

Both SDVDD (2.5V or 3.3V) and OVDD are specified relative to VDD.

5.2.1.1 Power Up Sequence

If OVDD/SDVDD are powered up with VDD at 0 V, then the sense circuits in the I/O pads will cause all pad

output drivers connected to the OVDD/SDVDD to be in a high impedance state. There is no limit on how

long after OVDD/SDVDD powers up before VDD must powered up. VDD should not lead the OVDD,

SDVDD or PLLVDD by more than 0.4 V during power ramp-up, or there will be high current in the internal

ESD protection diodes. The rise times on the power supplies should be slower than 1 µs to avoid turning

on the internal ESD protection clamp diodes.

The recommended power up sequence is as follows:

1. Use 1 µs or slower rise time for all supplies.

MCF5275 Integrated Microprocessor Family Hardware Specification, Rev. 2

10

Preliminary—Subject to Change Without Notice

Freescale Semiconductor

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