WM8941 datasheet(33/96 Pages) WOLFSON

номер детали	WM8941

подробное описание детали	Mono CODEC with Speaker Driver and Video Buffer

PDF	96 Pages

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производитель	WOLFSON [Wolfson Microelectronics plc]

домашняя страница	http://www.wolfsonmicro.com

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33 / 96 page

Pre Production

WM8941

PP, Rev 3.3, December 2007

LIMITER MODE

In limiter mode, the ALC will reduce peaks that go above the threshold level, but will not increase the

PGA gain beyond the starting level. The starting level is the PGA gain setting when the ALC is

enabled in limiter mode. If the ALC is started in limiter mode, this is the gain setting of the PGA at

start-up. If the ALC is switched into limiter mode after running in ALC mode, the starting gain will be

the gain at switchover. The diagram below shows an example of limiter mode.

Figure 13 ALC Limiter Mode Operation

ATTACK AND DECAY TIMES

The attack and decay times set the update times for the PGA gain. The attack time is the time

constant used when the gain is reducing. The decay time is the time constant used when the gain is

increasing. In limiter mode, the time constants are faster than in ALC mode. The time constants

are shown below in terms of a single gain step, a change of 6dB and a change of 90% of the PGAs

gain range.

Note that, these times will vary slightly depending on the sample rate used (specified by the SR

WM8941 датащи(PDF) 33 Page - Wolfson Microelectronics plc