WM8940GEFL/V Wolfson Microelectronics, WM8940GEFL/V Datasheet - Page 21

• 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
Table 5 Auxiliary Input Buffer Control
INPUT BOOST
The AUXMODE register bit controls the auxiliary input mode of operation:
In buffer mode (AUXMODE=0) the switch labelled AUXSW in Figure 7 is open and the signal at the
AUX pin will be buffered and inverted through the aux circuit using only the internal components.
In mixer mode (AUXMODE=1) the on-chip input resistor is bypassed, this allows the user to sum in
multiple inputs with the use of external resistors.
variations through this path from part to part due to the variation of the internal 20kΩ resistors
relative to the higher tolerance external resistors.
The input BOOST circuit has 3 selectable inputs: the input microphone PGA output, the AUX
amplifier output and the MICP input pin (when not using a differential microphone configuration).
These three inputs can be mixed together and have individual gain boost/adjust as shown in Figure
8.
The input PGA path can have a +20dB boost (PGABOOST=1) a 0dB pass through (PGABOOST=0)
or be completely isolated from the input boost circuit (INPPGAMUTE=1).
Figure 8 Input Boost Stage
R1
Power
management 1
R44
Input control
REGISTER
ADDRESS
6
3
BIT
AUXEN
AUXMODE
LABEL
0
0
DEFAULT
When used in this mode there will be gain
Auxiliary input buffer enable
0 = OFF
1 = ON
0 = inverting buffer
1 = mixer (on-chip input resistor bypassed)
DESCRIPTION
PD, Rev 4.2, April 2008
WM8940
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