STAC9750 Datasheet, PDF (42/73 Pages) Integrated Device Technology – VALUE-LINE TWO-CHANNEL AC’97 CODECS

STAC9750/9751
VALUE-LINE TWO-CHANNEL AC’97 CODECS
PC AUDIO
This read/write register is used to program power down states and monitor subsystem readiness.
The EAPD external control is also supported through this register.
Bit
EAPD
REF
ANL
DAC
ADC
Table 23. Powerdown Status Registers
Function
External Amplifier Power Down
VREF’s up to nominal level
Analog mixers, etc. ready
DAC section ready to playback data
ADC section ready to playback data
6.5.10.1. Ready Status
The lower half of this register is read only status, a 1 indicating that the subsection is ready. Ready is
defined as the subsection's ability to perform in its nominal state. When this register is written, the bit
values that come in on AC-Link will have no effect on read only bits 0-7.
When the AC-Link “CODEC Ready” indicator bit (SDATA_IN slot 0, bit 15) is a 1, it indicates that the
AC-Link and AC'97 control and status registers are in a fully operational state. The AC'97 controller
must further probe this Powerdown Control/Status Register to determine exactly which subsections,
if any are ready. When this register is written, the bit values that come in on AC-Link will have no
effect on read only bits 0-7.
6.5.11.
6.5.10.2. Powerdown Controls
The STAC9750/9751 is capable of operating at reduced power when no activity is required. The
state of power down is controlled by the Powerdown Register (26h). See the section “Low Power
Modes” for more information.
6.5.10.3. External Amplifier Power Down Control
The EAPD bit 15 of the Powerdown Control/Status Register (Index 26h) directly controls the output
of the EAPD output (pin 45), and produces a logical 1 when this bit is set to logic high. This function
is used to control an external audio amplifier power down. EAPD = 0 places approximately 0V on the
output pin, enabling an external audio amplifier. EAPD = 1 places approximately DVdd on the output
pin, disabling the external audio amplifier. Audio amplifiers that operate with reverse polarity will
likely require an external inverter to maintain software driver compatibility.
Extended Audio ID (28h)
Default: 0605h
D15
ID1
D7
SDAC
D14
ID0
D6
CDAC
D13
D12
Reserved
D5
D4
DSA1
DSA0
D11
REV1
D3
VRM
D10
REV0
D2
SPDIF
D9
AMAP
D1
DRA
D8
LDAC
D0
VRA
IDT™
VALUE-LINE TWO-CHANNEL AC’97 CODECS
42
STAC9750/9751
V 5.8 103106