ADAV4601 System Design Document
Confidential Information
Rev.1 August 2009
Analog Devices
Page 16
560
5.6nF
RL
(10K)
Vref
Ipeak
10uF
DC blocking Cap
Speaker out
560
5.6nF
RL
(10K)
Vref
Ipeak
10uF
DC blocking Cap
Speaker out
Figure 7: Vref powered up instantaneously
This is disabled in this register write, and the Vref is powered up at a gradual rate to ensure no pop is audible at the
output.
34 0005 A06F
This register write powers up the Auxiliary DACs; AUXDAC1 and AUXDAC3. It also powers up the DAC internal
reference buffer and puts all DACs into normal mode.
34 0006 023F
This register write powers up the headphone 1 amplifiers as well as the headphone 1 DACs.
Note:
AUXDAC4 and headphone 1 are connected together. Therefore, to use AUXDAC4, headphone 1 must be
powered up.
Note:
Theses two writes power up all available DACs on the ADAV4601. In power critical applications or depending
on the number of DACs required, the user can power up the minimum number of DACs needed for operation.
34 000B 2020
This write disables the tri-state on the headphone. By default the headphone outputs are tri-stated. This register
write enables the headphone outputs for normal use.
34 0329 0400
This register write adjusts the current to the Vref charger circuit. By writing this, it changes the initial change in the
Vref charge profile to a much more gradual increase, which further decreases the chances of hearing any pops on
the output of the ADAV4601. For more information on the Vref charger circuit, refer to Figure 9.
34 008D 06BA
This register write, enables the Vref charger circuitry which when set allows the gradual charging of the Vref voltage
from 0V up to 1.5V 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. See Figure 8 for more details.
Содержание ADAV4601
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