XWM8739LEFL データシートの表示（PDF） - Wolfson Microelectronics plc

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XWM8739LEFL

Stereo Audio ADC

Wolfson Microelectronics plc 

WM8739 / WM8739L

Advanced Information

The device can be powered off by writing to the POWEROFF bit of the Power Down register. In

POWEROFF mode the Control Interface and a small portion of the digital remain active. The

analogue VMID reference is disabled. As in STANDBY mode the crystal oscillator pin can be

independently controlled. Refer to Table 18.

DESCRIPTION

1

0

X

X

1

1

X

X

Table 18 Power Off Mode

POWEROFF, but with Crystal

Oscillator OSC available

POWEROFF, Crystal

oscillator not-available

DEVICE RESETTING

The WM8739 contains a power on reset circuit that resets the internal state of the device to a known

condition. The power on reset is applied as DCVDD powers on and released only after the voltage

level of DCVDD crosses a minimum turn off threshold. If DCVDD later falls below a minimum turn on

threshold voltage then the power on reset is re-applied. The threshold voltages and associated

hysteresis are shown in the Electrical Characteristics table.

The user also has the ability to reset the device to a known state under software control as shown in

the table below.

REGISTER

ADDRESS

0001111

Reset Register

BIT

LABEL

8:0 RESET

Table 19 Software Control of Reset

DEFAULT

DESCRIPTION

not reset

Reset Register

Writing 00000000 to register resets

device

When using the software reset. In 3-wire mode the reset is applied on the rising edge of CSB and

released on the next rising edge of SCLK. In 2-wire mode the reset is applied for the duration of the

ACK signal (approximately 1 SCLK period, refer to Figure 20).

AI Rev 2.2 September 2001

26

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