WM8940GEFL/V Wolfson Microelectronics, WM8940GEFL/V Datasheet - Page 65

• Manufacturer Part Number: WM8940GEFL/V
• Description: Audio CODECs Mono CODEC with Speaker Driver
• Manufacturer: Wolfson Microelectronics

Specifications of WM8940GEFL/V

• Maximum Operating Temperature: + 85 C
• Mounting Style: SMD/SMT
• Package / Case: QFN-24
• Minimum Operating Temperature: - 25 C
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

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Production Data
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Power Down:
1.
2.
3.
4.
5.
6.
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1.
2.
Notes:
In addition to the power on sequence, it is recommended that the zero cross functions are used
when changing the volume in the PGAs to avoid any audible pops and clicks.
Enable DAC soft mute (DACMU = 1).
Enable non-VMID derived bias generator (VMID_OP_EN = 1).
Enable on Bias Control (POB_CTRL = 1).
Disable analogue amplifier bias control (BIASEN = 0) and VMID (VMIDSEL[1:0] bits set to
OFF).
Enable Fast VMID Discharge (TOGGLE = 1) to discharge VMID capacitor.
Wait for VMID capacitor to fully discharge.
Enable speaker output mute (SPKMUTE = 1).
Disable DAC (DACEN = 0), speaker mixer (SPKMIX = 0), and speaker outputs (SPKPEN =
0 and SPKNEN = 0).
Reset all registers to their default state (software reset).
Turn off external power supply voltages.
This step enables the internal device bias buffer and the VMID buffer for unassigned
inputs/outputs. This will provide a startup reference for all inputs and outputs. This will
cause the inputs and outputs to ramp towards VMID in a way that is controlled and
predictable.
Choose the value of VMIDSEL bits based on the startup time (VMIDSEL = 10 for the
slowest startup, VMIDSEL = 11 for the fastest startup). Startup time is defined by the value
of the VMIDSEL bits (the reference impedance) and the external decoupling capacitor on
VMID.
Disable speaker mute (SPKMUTE = 0) and set SPKVOL = -57dB.
Ramp up the SPKVOL using the following values:
-27 dB, -21 dB, -15 dB, -13 dB, -11 dB, -9 dB, -8 dB, -7 dB, -6 dB, -5 dB, -4 dB, -3 dB, -2
dB, -1 dB, 0 dB.
Disable DAC soft mute (DACMU = 0).
PD, Rev 4.2, April 2008
WM8940
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