wm8940gefl-v Wolfson Microelectronics plc, wm8940gefl-v Datasheet - Page 67

• Manufacturer Part Number: wm8940gefl-v
• Description: Mono Codec With Speaker Driver
• Manufacturer: Wolfson Microelectronics plc

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Production Data
POP MINIMISATION
Table 60 POP Minimisation Control
Power-On-Bias Control (POB_CTRL) selects the bias current source for the output stages of the
WM8940. 0 selects the VMID derived bias source (normal operation), 1 selects a non-VMID derived
source which allows the output amplifiers to be enabled before VMID at start-up. This feature can be
used to minimise pops. Once VMID is enabled and has stabilised, POBCTRL should be set to 0.
Register SOFT_START is the enable bit for the VMID soft-start function. Setting the bit to 1 causes
charging of the VMID decoupling cap to follow a soft-start profile which minimises pops. This soft-
start profile has minimal impact on VMID charge time.
Fast VMID discharge is enabled using TOGGLE. Setting to 1 opens a low impedance discharge path
from VMID to GND. This function can be used during power down to reduce the discharge time of
the VMID decoupling cap. Must be set to 0 for normal operation.
R7
Additional
Control
REGISTER
ADDRESS
BIT
6
5
4
POB_CTRL
SOFT_START
TOGGLE
LABEL
DEFAULT
0
0
0
Power on Bias Control
0=normal (current bias based on VMID)
1=Startup (current bias not based on
VMID)
VMID Soft Start
0=disabled
1=enabled
Fast VMID Discharge
0=normal
1=enable (used during power-down)
DESCRIPTION
PD, Rev 4.2, April 2008
WM8940
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