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# AD1937 - does it support 8kHz

Hello,

I am using AD1937, I need to 8kHz sampling frequency application with AD1937 but first page in the manual  said that it supports 8kHz to 192kHz.

But I can't find how to set register to use for 8kHz.

How can I set AD1937 to support 8kHz?

Thanks.

Songhee.

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• Hi Songhee,

I apologize that the settings for the AD1937 are confusing.

The MCLKI pin functionality bits (0x00 [2:1]) should be set according to the closest correct multiplier based on the formula:

MCLK Freq = (48 kHz window factor of Fs) * (MCLKI multiplier setting in 0x00 [2:1]).

The (48 kHz window factor of Fs) is the factor such that when Fs is divided by 1, 2 or 4, the resulting factor lands in the window between 32 and 48 kHz.

• Fs = 32, 64 or 128 kHz yields a factor if 32 kHz.
• Fs = 44.1, 88.2 or 176.4 kHz yields a factor if 44.1 kHz.
• Fs = 48, 96 or 192 kHz yields a factor of 48 kHz.

The MCLKI /XI pin finctionality bitfield sets the internal workings of the AD1937 PLL to provide the correct internal clocks for both the ADCs and DACs. This is a separate setting from the Sample Rate (Fs) selection.

• If you are using a 24.576 MHz clock and 48 kHz Fs, set the bits to 10 (512 multiplier).
• If you are using a 12.288 MHz clock and 128 kHz Fs, set the bits to 01 (384 multiplier).
• If you are using a 22.579 MHz clock and 88.2 kHz Fs, set the bits to 00 (256 muliplier).

The DAC and ADC clock source selections (0x01 [1] and [0]) should both be set to 0 (PLL clock) if the PLL is to be used.

The DAC and ADC Sample rate windows (0x02 [2:1] and 0x0E [7:6]) should be set according to the desired Fs.

Best regards,

Coleman

• Hi Songhee,

I apologize that the settings for the AD1937 are confusing.

The MCLKI pin functionality bits (0x00 [2:1]) should be set according to the closest correct multiplier based on the formula:

MCLK Freq = (48 kHz window factor of Fs) * (MCLKI multiplier setting in 0x00 [2:1]).

The (48 kHz window factor of Fs) is the factor such that when Fs is divided by 1, 2 or 4, the resulting factor lands in the window between 32 and 48 kHz.

• Fs = 32, 64 or 128 kHz yields a factor if 32 kHz.
• Fs = 44.1, 88.2 or 176.4 kHz yields a factor if 44.1 kHz.
• Fs = 48, 96 or 192 kHz yields a factor of 48 kHz.

The MCLKI /XI pin finctionality bitfield sets the internal workings of the AD1937 PLL to provide the correct internal clocks for both the ADCs and DACs. This is a separate setting from the Sample Rate (Fs) selection.

• If you are using a 24.576 MHz clock and 48 kHz Fs, set the bits to 10 (512 multiplier).
• If you are using a 12.288 MHz clock and 128 kHz Fs, set the bits to 01 (384 multiplier).
• If you are using a 22.579 MHz clock and 88.2 kHz Fs, set the bits to 00 (256 muliplier).

The DAC and ADC clock source selections (0x01 [1] and [0]) should both be set to 0 (PLL clock) if the PLL is to be used.

The DAC and ADC Sample rate windows (0x02 [2:1] and 0x0E [7:6]) should be set according to the desired Fs.

Best regards,

Coleman

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