2 automatic path configuration, 1 standby release – Rainbow Electronics AT73C246 User Manual
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11050A–PMAAC–07-Apr-10
AT73C246
master clock must be running to properly shutdown the codec. This time linearly varies with
ASR_TIME value. See
The analog power-off time corresponds to the VMID’s discharge time specified in
: T
MID_OFF
.
Finally, the wait step #8 in
“Audio Codec Typical Control Sequence” on page 57
needs to acco-
modate the digital power-off time + the analog power-off time.
12.4.2
Automatic Path Configuration
In this automatic path mode, the audio path control is fully managed by the AUTOSTART(0x10)
register and more precisely by the following bits:
• ENAC (Enable Audio codec),
• STANDBY
(Audio standby) and
• PATHSEL (Audio path selection).
When the audio controller detects a change in these bits, it generates sequential controls to the
audio codec sub-functions (power-up, gain ramping, unmute,…) with the right timing and order.
Notes: 1. Audio STANDBY does not refer to the PMU STANDBY state as defined in
Manager Functional State Diagram” on page 25
. The audio STANDBY mode activated by reg-
ister AUTOSTART (0x10) only refers to the audio codec controller.
12.4.2.1
STANDBY Release
Once the CODEC is started and in standby mode (ENAC=1 and STANDBY=1, step #5 in
Codec Typical Control Sequence” on page 57
), the audio path is simply selected by PATHSEL
bits.
At STANDBY release (STANDBY=0), the audio controller will:
• Power-up the requested audio sub-functions. To do so, the audio controller makes WRITE
accesses to the registers
– INPUT_CONTROL (0x1E),
– OUTPUT_CONTROL (0x1F) and
– INPUT_MIXER (0x20).
• Ramp-up the concerned path gains from mute to their current register value.
Notes: 1. Changing PATHSEL value with STANDBY=1 does not changes the codec state. It remains in
STANDBY mode.
2. The audio controller always ensures minimum power consumption by powering only needed
sub-functions.
3. Audio parameters (volume, mute, effects…) can be modified before or after releasing the
standby mode.
Table 12-1.
Audio Codec Maximum Power-off Time
ASR_TIME
Power-off time (ms)
00
375
01
750
10
1500
11
3000