ADAV4601 System Design Document
Confidential Information
Rev.1 August 2009
Analog Devices
Page 15
SECTION 2 – POWERING UP THE ADAV4601
This section explains the recommended sequence of register writes which are required for powering up the device.
These register writes are required to ensure that there is no noise at the output of the audio processor while the
part is going from the reset state to full power mode. Please refer to the Appendix A – Detailed Register
Descriptions for more details on register settings
WRITE SEQUENCE EXPLAINED
The ADAV4601 is controlled via I
2
C; therefore the following sequence is given in the following format
34 AAAA DDDD
Where 34 is the I
2
C address of the ADAV4601, AAAA is the register address in the ADAV4601 that is being written to
and DDDD is the data that is being written.
POWER UP SEQUENCE
After power has been applied initially to the part, nothing in the device is powered up. This means that the
ADAV4601 is in reset state.
The recommended power up sequence from this state is therefore as follows.
34 0000 0000
This sets the PLL Frequency to be equal to 512*Fs. Given that the sampling frequency is given as 48kHz, this means
the MCLKI frequency is set to be 24.576Mhz. Depending on the clock frequency required, this register must be set
accordingly.
34 0006 0200
This register write powers up the PLL block in the ADAV4601. This bit must be set to ensure the correct operation of
the device.
34 000A 0801
Setting this register to this enables the PLL for use. Like the above register write, this bit must be set to ensure the
correct operation of the device. There should be a delay of 15ms (worst-case scenario) after this write to ensure that
the PLL has locked to the MCLKI frequency.
34 008D 0628
This register write disables the clamp on the headphone output. By default, the headphone output is connected
directly to ground. Once this is disabled, the headphone is in normal operation. This register write also disables the
voltage reference, which is enabled by default. When enabled and the DACs powered up, Vref is at 1.5V. This sharp
transition from 0V to 1.5V causes a pop at the output of the part. See Figure 7 for more details.
Содержание ADAV4601
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