WM8978 Wolfson Microelectronics Ltd., WM8978 Datasheet - Page 10
Manufacturer Part Number
The WM8978 is a low power, high quality stereo codec designed for portable applications such as Digital still camera or Digital Camcorde
Wolfson Microelectronics Ltd.
not apply to ramping down the gain when the signal is too loud, which happens without a delay.
with no signal applied. (No Auto-zero or Automute function is employed in achieving these results).
the other. Measured by applying a full scale signal to one channel input and measuring the level of signal apparent at
the other channel output.
SPKBOOST is set then SPKVDD should be 1.5xAVDD to prevent clipping taking place in the output stage (when
PGA gains are set to 0dB).
Input level to RIP and LIP is limited to a maximum of -3dB or THD+N performance will be reduced.
Note when BEEP path is not enabled then AUXL and AUXR have the same input impedances.
Hold Time is the length of time between a signal detected being too quiet and beginning to ramp up the gain. It does
Ramp-up and Ramp-Down times are defined as the time it takes for the PGA to sweep across 90% of its gain range.
All hold, ramp-up and ramp-down times scale proportionally with MCLK
Signal-to-noise ratio (dB) – SNR is a measure of the difference in level between the full scale output and the output
THD+N (dB) – THD+N is a ratio, of the rms values, of (Noise + Distortion)/Signal.
Channel Separation (dB) – Also known as Cross-Talk. This is a measure of the amount one channel is isolated from
The maximum output voltage can be limited by the speaker power supply.
If OUT3BOOST, OUT4BOOST or
PTD Rev 2.6 November 2005
Preliminary Technical Data