LM4935 datasheet(55/112 Pages) NSC

Part #	LM4935

Description	Audio Sub-System with Dual-Mode Stereo Headphone and Mono High Efficiency Loudspeaker Amplifiers and Multi-Purpose ADC

PDF	112 Pages

Scroll/Zoom	100%

Manufacturer	NSC [National Semiconductor (TI)]

Direct Link	http://www.national.com

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55 / 112 page

12.0 Status & Control Registers (Continued)

12.32 DIGITAL AUDIO DATA FORMATS

I2S master mode can only be used when the DAC is enabled unless the ADC_I2S_M bit is set. PCM Master mode can only be

used when the ADC is enabled. If the PCM receiver interface is operated in slave mode the clock and sync should be enabled

at the same time as the PCM receiver uses the first PCM frame to calculate the PCM interface format. This format can not be

changed unless a soft reset is issued. It is strongly recommended that the LM4935 is operated in master mode as this eliminates

the risk of sample rate mismatch between the data converters and the audio interfaces.

In master mode the I2S_CLK has a 60/40 duty cycle and a frequency of 50*fs. In slave mode the PCM and I2S receivers only

record the 1st 16 and 18 bits of the serial words respectively. The I2S format is as follows:

When SAR SDO data is passed to the I2S, it is left aligned (MSB aligned) to allow lower I2S resolutions to be used.

If the DAC is driven from the PCM interface then the left channel of the DAC is used and the right channel is inactive.

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FIGURE 10. I

2S Serial Data Format (Default Mode)

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FIGURE 11. PCM Serial Data Format (16 bit Slave Example)

LM4935 Datasheet(PDF) 55 Page - National Semiconductor (TI)