WM8731 datasheet(43/56 Pages) WOLFSON

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WM8731

Advanced Information

WOLFSON MICROELECTRONICS LTD

AI Rev 2.0 February 2001

To control the WM8731 on the 2-wire bus the master control device must initiate a data transfer by

establishing a start condition, defined by a high to low transition on SDIN while SCLK remains high.

This indicates that an address and data transfer will follow. All peripherals on the 2-wire bus respond

to the start condition and shift in the next eight bits (7-bit address + R/W bit). The transfer is MSB

first. The 7-bit address consists of a 6-bit base address + a single programmable bit to select one of

two available addresses for this device (see table 24). If the correct address is received and the R/W

bit is ‘0’, indicating a write, then the WM8731 will respond by pulling SDIN low on the next clock pulse

(ACK). The WM8731 is a write only device and will only respond to the R/W bit indicating a write. If

the address is not recognised the device will return to the idle condition and wait for a new start

condition and valid address.

Once the WM8731 has acknowledged a correct address, the controller will send eight data bits (bits

B[15]-B[8]). WM8731 will then acknowledge the sent data by pulling SDIN low for one clock pulse.

The controller will then send the remaining eight data bits (bits B[7]-B[0]) and the WM8731 will then

acknowledge again by pulling SDIN low.

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 WM8731 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.

POWER DOWN MODES

The WM8731 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.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

LINEINPD

Line Input Power Down

1 = Enable Power Down

0 = Disable Power Down

MICPD

Microphone Input an Bias

Power Down

1 = Enable Power Down

0 = Disable Power Down

ADCPD

ADC Power Down

1 = Enable Power Down

0 = Disable Power Down

DACPD

DAC Power Down

1 = Enable Power Down

0 = Disable Power Down

OUTPD

Line Output Power Down

1 = Enable Power Down

0 = Disable Power Down

OSCPD

Oscillator Power Down

1 = Enable Power Down

0 = Disable Power Down

CLKOUTPD

CLKOUT power down

1 = Enable Power Down

0 = Disable Power Down

0000110

Power Down

Control

POWEROFF

Power Off Device

1 = Device Power Off

0 = Device Power On

Table 25 Power Conservation Modes Software Control

WM8731 Datasheet(PDF) 43 Page - Wolfson Microelectronics plc

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