WM8734SEFL Wolfson Microelectronics, WM8734SEFL Datasheet - Page 34

• Manufacturer Part Number: WM8734SEFL
• Description: Audio CODECs Stereo CODEC
• Manufacturer: Wolfson Microelectronics

Specifications of WM8734SEFL

• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: QFN-28
• Minimum Operating Temperature: - 25 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

WM8734
POWER DOWN MODES
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A stop condition is defined when there is a low to high transition on SDIN while SCLK is high. If a
start or stop condition is detected out of sequence at any point in the data transfer then the device
will jump to the idle condition.
After receiving a complete address and data sequence the WM8734 returns to the idle state and
waits for another start condition. Each write to a register requires the complete sequence of start
condition, device address and R/W bit followed by the 16 register address and data bits.
Note that the 16 bit control word is made up of 7 address bits, B[15:9], and 9 data bits, B[8:0].
These are transmitted as 2 blocks of 8 bits. The first block contains 7 address bits and the data
HSB. The second block contains the 8 data LSBs.
The WM8734 contains power conservation modes in which various circuit blocks may be safely
powered down in order to conserve power. This is software programmable as shown in the table
below.
Table 18 Power Conservation Modes Software Control
When writing to the powerdown register bits 1,5 and 6 should be set to ‘1’.
The power down control can be used to either a) permanently disable functions when not required in
certain applications or b) to dynamically power up and down functions depending on the operating
mode, e.g.: during playback or record. Please follow the special instructions below if dynamic
implementations are being used.
LINEINPD: Simultaneously powers down both the Line Inputs. This can be done dynamically without
any audible effects either on the ADC or to the Line Outputs in Bypass mode. This is of use when the
device enters Playback, Pause or Stop modes or the Microphone input has been selected.
ADCPD: Powers down the ADC and ADC Filters. If this is done dynamically then audible pops will
result if any signals were present through the ADC. To overcome this whenever the ADC is to be
powered down, either mute the Microphone Input (MUTEIN) or MUTELINEIN, then change ADCPD.
This is of use when the device enters Playback, Pause or Stop modes regardless of whether
Microphone or Line Inputs are selected.
DACPD: Powers down the DAC and DAC Digital Filters. If this is done dynamically then audible pops
will result unless the following guidelines are followed. In order to prevent pops, the DAC should first
be soft-muted (DACMU), the output should then be de-selected from the line and headphone output
(DACSEL), then the DAC powered down (DACPD). This is of use when the device enters Record,
Pause, Stop or Bypass modes.
The device can be put into a standby mode (STANDBY) by powering down all the audio circuitry
under software control as shown in Table 18. Provision has been made to independently power off
these areas according to Table 19.
0000110
Power Down
Control
REGISTER
ADDRESS
0
2
3
4
7
BIT
LINEINPD
ADCPD
DACPD
OUTPD
POWEROFF
LABEL
1
1
1
1
1
DEFAULT
Line Input Power Down
1 = Enable Power Down
0 = Disable Power Down
ADC Power Down
1 = Enable Power Down
0 = Disable Power Down
DAC Power Down
1 = Enable Power Down
0 = Disable Power Down
Line Output Power Down
1 = Enable Power Down
0 = Disable Power Down
Power Off Device
1 = Device Power Off
0 = Device Power On
PD, Rev 4.3, January 2009
DESCRIPTION
Production Data
34