wm8982gefl-v Wolfson Microelectronics plc, wm8982gefl-v Datasheet - Page 19

• Manufacturer Part Number: wm8982gefl-v
• Description: Mono Codec With Speaker Driver And Video Buffer
• Manufacturer: Wolfson Microelectronics plc

Pre-Production
INPUT SIGNAL PATH
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CONTROL INTERFACES
To allow full software control over all its features, the WM8982 offers a choice of 2 or 3 wire MPU
control interface. It is fully compatible and an ideal partner for a wide range of industry standard
microprocessors, controllers and DSPs.
Selection between the modes is via the MODE pin. In 2 wire mode the address of the device is fixed
as 0011010.
CLOCKING SCHEMES
WM8982 offers the normal audio DAC clocking scheme operation, where 256fs MCLK is provided to
the DAC and ADC.
A PLL is included which may be used to generate these clocks in the event that they are not
available from the system controller. This PLL uses an input clock, typically the 12MHz USB or ilink
clock, to generate high quality audio clocks. If this PLL is not required for generation of these clocks,
it can be reconfigured to generate alternative clocks which may then be output on the GPIO pins and
used elsewhere in the system.
VIDEO BUFFER
The WM8982 incorporates a current mode output video buffer with an input 3
(LPF) and clamp. The gain through this buffer can be programmed as 0dB or 6dB via the control
interface. The current mode output means that the signal swing seen at the output of the buffer will
be the same as that at the connection to the receiving equipment (e.g. a TV). Note that the input to
the receiver should be AC coupled and terminated to 75Ω, as is standard, for best performance.
POWER CONTROL
The WM8982 provides the ability to disable any unused parts of the circuitry under software control,
to save power and includes standby and power off modes.
The WM8982 has a number of flexible analogue inputs, consisting of an input PGA stage followed by
a boost/mix stage which is input to the ADC. The input path has three input pins which can be
configured in a variety of ways to accommodate single-ended or differential microphones. There is
an auxiliary input pin which can be fed into to the input boost/mix stage as well as driving into the
output path. A bypass path exists from the output of the boost/mix stage into the output mixer.
MICROPHONE INPUT
The WM8982 can accommodate a variety of microphone configurations including single ended and
differential inputs. The inputs to the input PGA are MICN, MICP and LINEIN.
In single-ended microphone input configuration the microphone signal should be input to MICN and
the internal NOR gate configured to clamp the non-inverting input of the input PGA to VMID.
In differential mode the larger signal should be input to LIP and the smaller (eg noisy ground
connections) should be input to LIN.
PP, Rev 3.2, September 2008
rd
order Low Pass Filter
WM8982
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