ADAV4601 System Design Document
Confidential Information
Rev.1 August 2009
Analog Devices
Page 21
Note:
By default this power up sequence puts data from SRC1 out on all outputs of the ADAV4601. This will have to
be changed depending on the flow used.
POWER DOWN SEQUENCE
From the powered up state that was described in the previous section. The following is the recommended
sequence when powering down the ADAV4601.
34 0121 0000
Mute the audio flow using the fast mute control register. This mutes all outputs on the ADAV4601. It is
recommended to wait for 100ms after performing this write before performing the next I
2
C write.
34 008D 07A0
Power up the iDAC buffer, this is used to disconnect the iDAC and the DAC current to voltage converter. It is
recommended to wait for 10ms after this write so as to ensure that the iDAC buffer has been fully powered up.
34 000B 2121
34 000B 2222
34 000B 2323
34 000B 2424
34 000B 2525
34 000B 2626
34 000B 2727
34 000B 2828
34 000B 2929
34 000B 2A2A
These register writes decrease the gain of the headphone amplifier in steps of -1.5dB from 0dB to -15dB. This is an
additional precaution to ensure that no pops or clicks are heard at the headphone outputs.
34 008D 06A0
This register write disconnects the iDAC from the current to voltage converter. This means that any large current
flow that may occur on the iDAC will not be heard at the output.
34 0329 0400
This register write adjusts the current to the Vref discharger circuit. By writing this, it changes the initial change in
the Vref charge profile to a much more gradual decrease, which further decreases the chances of hearing any pops
on the output of the ADAV4601.
34 008D 06A9
This register write, enables the Vref discharger circuitry which when set allows the gradual discharging of the Vref
voltage from 1.5V down to 0V in an S shaped profile, which ensures that there are no sharp current spikes at the
output of the part, which would otherwise cause noise. It is recommended that there is delay of at least 500ms so as
to be sure the capacitor at the Vref pin has discharged fully. Refer to Figure 13 for more details on the output of the
Vref discharger circuit.
Содержание ADAV4601
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