MSC7118 datasheet(42/60 Pages) FREESCALE

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MSC7118 Low-Cost 16-bit DSP with DDR Controller Data Sheet, Rev. 7

Hardware Design Considerations

Freescale Semiconductor

3.2.2.2

Case 2

The power-up sequence is as follows:

Turn on the VDDIO (3.3 V) supply first.

Turn on the VDDC (1.2 V) and VDDM (2.5 V) supplies simultaneously (second).

Turn on the VREF (1.25 V) supply last (third).

Note:

Make sure that the time interval between the ramp-up of VDDIO and VDDC/VDDM is less than 10 ms.

The power-down sequence is as follows:

Turn off the VREF (1.25 V) supply first.

Turn off the VDDM (2.5 V) supply second.

Turn off the VDDC (1.2 V) supply third.

Turn of the VDDIO (3.3 V) supply fourth (last).

Use the following guidelines:

•

Make sure that the time interval between the ramp-down for VDDIO and VDDC is less than 10 ms.

•

Make sure that the time interval between the ramp-up or ramp-down for VDDC and VDDM is less than 10 ms for

power-up and power-down.

•

Refer to Figure 27 for relative timing for Case 2.

Figure 27. Voltage Sequencing Case 2

Time

Ramp-down

Ramp-up

VDDIO = 3.3 V

VDDM = 2.5 V

VDDC = 1.2 V

VREF = 1.25 V

<10 ms

MSC7118 Datasheet(PDF) 42 Page - Freescale Semiconductor, Inc