Hi.
I have some PCM1733 DACs.
The data sheet states these are 18-bit dacs with a built in? 8x oversampling filter.
The input is I2S.
How can I interface these to a 16-bit I2S signal eg to replace theTDA1541 and SAA???? in an old Philips cd-p?
Would I have to introduce extra clocks for the 2 extra bits?
Andy
I have some PCM1733 DACs.
The data sheet states these are 18-bit dacs with a built in? 8x oversampling filter.
The input is I2S.
How can I interface these to a 16-bit I2S signal eg to replace theTDA1541 and SAA???? in an old Philips cd-p?
Would I have to introduce extra clocks for the 2 extra bits?
Andy
Its the datasheets,.................
You are replacing one I2S bus device with another, it as simple as it gets, even a six sigma black belt can do it. The position of the MSB is fixed regardless of wordlength and the clock is continuous. Add 256Fs MCLK and you are done.
The TDA1540 is not an I2S bus device.
poynton said:
You are replacing one I2S bus device with another, it as simple as it gets, even a six sigma black belt can do it. The position of the MSB is fixed regardless of wordlength and the clock is continuous. Add 256Fs MCLK and you are done.
poynton said:
The TDA1540 is not an I2S bus device.
Re: Its the datasheets,.................
Thats what I thought. I was wanting to replace the SAA7220 ( 4x filter ) and TDA1541 with the pcm1733 (8x filter). What worries me is the specs. for the PCM1733 says it accepts 18 data not 16 bit as per SAA7220. What about the extra 2 bits? or will the PCM1733 accept 16 bit data without problems, every thing sorted by the 16 bit I2S lines?
PS - whats a 6 sigma black belt?
rfbrw said:
Thats what I thought. I was wanting to replace the SAA7220 ( 4x filter ) and TDA1541 with the pcm1733 (8x filter). What worries me is the specs. for the PCM1733 says it accepts 18 data not 16 bit as per SAA7220. What about the extra 2 bits? or will the PCM1733 accept 16 bit data without problems, every thing sorted by the 16 bit I2S lines?
OOPS - finger problem!
PS - whats a 6 sigma black belt?
Re: Re: Its the datasheets,.................
An 18 bit device will accept anything up to 18 bits. Unlike some other devices, the '1733 will not explicitly limit the I2S wordlength to 16 bits so the state of the last two bits will depend on the source of I2S data.
The SAA7210 extends the LSB such that if the LSB is Low the rest of the frame is low and vice versa. This will result in a dynamic 2 bit offset. You can get rid of this, the CS8420, with its input register fixed at 24bits in I2S mode, goes so far as to caution against having this offset in the datasheet, but in this case it will probably be insignificant.
A consultant/giver-of-seminars in TQM,DFM,DFT,ISO9000 and other assorted gobbledegook of much exalted guru status. Unfortunately more than a few couldn't tell a flat pack from a flap jack.
poynton said:
An 18 bit device will accept anything up to 18 bits. Unlike some other devices, the '1733 will not explicitly limit the I2S wordlength to 16 bits so the state of the last two bits will depend on the source of I2S data.
The SAA7210 extends the LSB such that if the LSB is Low the rest of the frame is low and vice versa. This will result in a dynamic 2 bit offset. You can get rid of this, the CS8420, with its input register fixed at 24bits in I2S mode, goes so far as to caution against having this offset in the datasheet, but in this case it will probably be insignificant.
A consultant/giver-of-seminars in TQM,DFM,DFT,ISO9000 and other assorted gobbledegook of much exalted guru status. Unfortunately more than a few couldn't tell a flat pack from a flap jack.
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