wm9708 Wolfson Microelectronics plc, wm9708 Datasheet - Page 25

• Manufacturer Part Number: wm9708
• Description: Ac?97 Revision 2.1 Audio Codec
• Manufacturer: Wolfson Microelectronics plc

Production Data
POWERDOWN CONTROL/STATUS REGISTER (INDEX 26h)
w
This read/write register is used to program Powerdown states and monitor subsystem readiness. The
lower half of this register is read only status, a 1 indicating that the subsection is ready. Ready is
defined as the subsection able 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 to 7.
When the AC-link Codec Ready indicator bit (SDATAIN slot 0, bit 15) is a 1 it indicates that the AC-
link and the WM9708 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.
Table 10 Powerdown Status Register Function
The powerdown modes are as follows. The first three bits are to be used individually rather than in
combination with each other. The last bit PR3 can be used in combination with PR2 or by itself. PR0
and PR1 control the PCM ADCs and DACs only. PR6 is not supported by the WM9708.
Table 11 Powerdown Control Register Function
Figure 13 An Example of the WM9708 Powerdown/Powerup Flow
Figure 13 illustrates one example procedure to do a complete Powerdown of the WM9708. From
normal operation sequential writes to the Powerdown Register are performed to Powerdown the
WM9708 a piece at a time. After everything has been shut off (PR0 to PR3 set), a final write (of PR4)
can be executed to shut down the WM9708’s digital interface (AC-link).
WRITE BIT
PR0
PR1
PR2
PR3
PR4
PR5
PR6
EAPD
READ BIT
DAC
ADC
REF
ANL
NORMAL
PR0 = 0 AND
ADC = 1
PR0 = 1
FUNCTION
VREFs up to nominal level
Analogue mixers, etc ready
DAC section ready to accept data
ADC section ready to transmit data
FUNCTION
PCM in ADCs and input Mux Powerdown
PCM out DACs Powerdown
Analogue mixer Powerdown
(VREF still on)
Analogue mixer Powerdown (VREF off)
Digital interface (AC-link) Powerdown
(external clock off)
Internal clock disable
HP amp Powerdown – not supported
External amplifier Powerdown
READY = 1
ADCs OFF
PR0
PR1 = 0 AND
DAC = 1
PR1 = 1
DACs OFF
PR1
PR2 = 0 AND
ANL = 1
DEFAULT
PR2 = 1
OFF PR2 OR
ANALOGUE
PR3
PR4 = 1
COLD RESET
DIGITAL I/F
OFF PR4
RESET
WARM
PD, Rev 4.2, August 2009
CODA LINK
WM9708
SHUT OFF
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