WM8985GEFL Wolfson Microelectronics, WM8985GEFL Datasheet - Page 23

• Manufacturer Part Number: WM8985GEFL
• Description: Audio CODECs Multimedia CODEC with Class D HP
• Manufacturer: Wolfson Microelectronics

Specifications of WM8985GEFL

• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: QFN-32
• Minimum Operating Temperature: - 25 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Production Data
RECOMMENDED POWER UP/DOWN SEQUENCE
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In order to minimise output pop and click noise, it is recommended that the WM8985 device is
powered up and down under control using the following sequences:
Power Up:
Power Down
Notes:
1.
2.
3.
1.
2.
3.
4.
5.
6.
7.
8.
9.
10. Setup digital interface, input amplifiers, PLL, ADCs and DACs for desired operation.
11. Disable VMID independent current bias, POBCTRL = 0.
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.
1.
2.
3.
4.
5.
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. This is done by following the power-up sequence omitting steps 4 to 8.
Discharge time constant is determined by the values of analogue output capacitors.
Turn on external power supplies. Wait for supply voltage to settle.
Set low analogue bias mode, BIASCUT = 1
Enable thermal shutdown TSDEN = TSOPCTRL = 1
Enable Internal bias BIASEN = 1.
Mute all outputs and set PGAs to minimum gain, R52 to R57 = 0x140h.
Enable VMID independent current bias, POBCTRL = 1.
Enable required outputs, DACs and mixers.
Enable VMID with required charge time e.g. VMIDSEL=01.
Wait 500ms
Disable Thermal shutdown, TSDEN = TSOPCTRL = 0
Disable VMIDSEL=00 and BIASEN=0
Wait for VMID to discharge
Power off registers R1, R2, R3 = 0x000h
Remove external power supplies
2
:
1
3
PD, Rev 4.6, July 2009
WM8985
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