WM8711BL datasheet(19/43 Pages) WOLFSON

19 / 43 page

Production Data

WM8711BL

PD, Rev 4.1, April 2007

The recommended external components required to complete the application are shown in Figure 11.

AGND

HPOUT

Figure 11 Headphone Output Application Drawing

Recommended values are C1 = 220uF (10V electrolytic), R1 = 47k

C1 forms a DC blocking capacitor to isolate the dc of the HPOUT from the headphones. R1 form a

pull down resistor to discharge C1 to prevent the voltage at the connection to the headphones from

rising to a level that may damage the headphones.

DEVICE OPERATION

DEVICE RESETTING

The WM8711BL 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.

ADDRESS

BIT

LABEL

DEFAULT

DESCRIPTION

0001111

Reset Register

8:0

RESET

not reset

Reset Register

Writing 00000000 to register resets

device

Table 5 Software Control of Reset

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 21).

WM8711BL Datasheet(PDF) 19 Page - Wolfson Microelectronics plc