WM8985GEFL Wolfson Microelectronics, WM8985GEFL Datasheet - Page 91

• 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
POP MINIMISATION
w
VMID
Table 51 VMID Impedance Control
BIASEN
Table 52 Analogue Bias Control
POBCTRL
WM8985 has two bias generators. A noisy bias derived from AVDD and a low noise bias derived
from VMID. POBCTRL is use to switch between the two bias generators. During power up, the
AVDD derived bias is available as soon as AVDD is applied; the VMID derived bias is available once
the VMID node has charged up.
Note: POBCTRL should be asserted during power up to minimize pops and then de-
asserted at the end of the power up sequence to give best performance. Refer to
Recommended Power Up/Down
The analogue circuitry will not operate unless VMID is enabled. The impedance of the VMID resistor
string, together with the decoupling capacitor on the VMID pin will determine the start-up time of the
VMID circuit.
The analogue amplifiers will not operate unless BIASEN is enabled.
R1 (01h)
Power
management 1
R1 (01h)
Power
management 1
R42
OUT4 to ADC
REGISTER
REGISTER
REGISTER
ADDRESS
ADDRESS
ADDRESS
1:0
3
2
BIT
BIT
BIT
VMIDSEL
BIASEN
POB
CTRL
LABEL
LABEL
LABEL
0
0
DEFAULT
DEFAULT
00
DEFAULT
Analogue amplifier bias control
0 = disabled
1 = enabled
VMID independent current bias control
0 = Disable VMID independent current
bias
1 = Enable VMID independent current bias
Reference string impedance to VMID pin
00 = off (250k Ω VMID to AGND1)
01=75k Ω
10=300k Ω
11=5k Ω
DESCRIPTION
DESCRIPTION
DESCRIPTION
PD, Rev 4.6, July 2009
WM8985
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