WM8758B datasheet(22/90 Pages) WOLFSON

22 / 90 page

WM8758B

Production Data

PD, Rev 4.4, January 2012

RECOMMENDED POWER UP/DOWN SEQUENCE

In order to minimise output pop and click noise, it is recommended that the WM8758B device is

powered up and down under control using the following sequences:

Power Up:

Turn on external power supplies. Wait for supply voltage to settle.

Set low bias mode, BIASCUT = 1.

Enable HPCOM = 1, LINECOM = 1.

Mute all Outputs and set PGAs to minimum gain, R52 to R57 = 0x140h.

Enable L/ROUT1

Enable L/ROUT2

Enable VMID independent current bias, POBCTRL = 1.

Enable required DACs and mixers.

Enable VMIDSEL=01, BIASEN = 1 and BUFIOEN = 1

10. Setup digital interface, input amplifiers, PLL, ADCs and DACs for desired operation.

11. Wait 100ms to allow VMID to rise sufficiently before unmuting outputs

12. Unmute L/ROUT1 and set desired volume, e.g. for 0dB R52 and R53 = 0x139h.

13. Unmute L/ROUT2 and set desired volume, e.g. for 0dB R54 and R55 = 0x139h.

14. Disable VMID independent current bias, POBCTRL = 0.

Power Down:

Disable Thermal shutdown

Enable VMIDTOG = 1

Disable VMIDSEL=00 and BUFIOEN=0

Wait for VMID to discharge

Power off registers R1, R2, R3 = 0x000h

Remove external power supplies

Notes:

Charging time constant is determined by impedance selected by VMIDSEL and the value of

decoupling capacitor connected to VMID pin.

It is possible to interrupt the power down sequence and power up to VMID before the allocated

VMID discharge time.

WM8758B bảng dữ liệu(PDF) 22 Page - Wolfson Microelectronics plc