MAS3549F datasheet(19/92 Pages) MICRONAS

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DATA SHEET

MAS 35x9F

Micronas

June 30, 2004; 6251-505-1DS

2.11.2.1.Important Advice for Turn-on and Operat-

ing Voltage

Before the 2.2 V are programmed at the DCDC con-

verter, DSP+Codec must be enabled.

Operating and Turn-Off is possible down to 2.2 V.

The sequence should be similar to the following:

1. Start DCDC

2. Set DCDC to 2.5 V

Turn on DSP+Codec

Write App-Select memory cell

Read App-Running Mem cell

If okay: Set DCDC to 2.2 V

Set other mem cells

Set other codec registers

.....

3. Demute...send data

4. Mute...stop data.....loop "3)" "4)"...

5. Turn off DSP+Codec

goto "2)"

etc.....

The signal at pin PUP will return to low only when both

PUPn flags (I2C subaddress 76hex) have returned to

zero. Care must be taken when changing both DC/DC

output voltages to higher values. In this case, both out-

put voltages are momentarily insufficient to keep the

PUPn flags up; the resulting dip in the signal at the

PUP pin may, in turn, reset the microcontroller. To

avoid this condition, only one DC/DC output voltage

should be changed at a time. Before modifying the

second voltage, the microcontroller must wait for the

PUPn flag of the first voltage to be set again.

If only DC/DC converter 1 is used, the reference volt-

age of the second, unused converter should be set to

a lower value than that of converter 1, and its pin

VSENS2 should be connected to VDD.

The operating mode pulse width modulation, or pulse

frequency modulation, are controlled at I2C subad-

dress 76hex, the operating frequency at I

2C subad-

dress 77hex.

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