I count 1A for RPI, 1A for DSP, then there is esp32, isolators for i2c, i2s, mulpiplexer, oled, relay, encoder and other small things + margin so its not heating a lot.
Think 4A too much?
Think 4A too much?
What you think about LM29300T-5.0-TT? 5V 3A
https://www.tme.eu/Document/c275d0a0564368d135c053a16969d679/LM2930x.pdf
https://www.tme.eu/Document/c275d0a0564368d135c053a16969d679/LM2930x.pdf
That's why I choose TO-3 package, could add a bigger heatsink to it. How much heat needs to be disipated? I cannot find that in pdf
Power dissipation in a linear regulator is the current passing through it times the voltage drop across it.
370mV is the drop-out voltage. That's the minimum voltage drop across the regulator where it can still regulate. However, that's not the voltage drop that will probably be across it in most cases.
Let's say you have a transformer, rectifier and filter cap that put out 9.3 VDC. Let's also say the regulator output voltage is going to be 5V. Then the voltage drop across the regulator will be 4.3V.
Let's say you have a transformer, rectifier and filter cap that put out 9.3 VDC. Let's also say the regulator output voltage is going to be 5V. Then the voltage drop across the regulator will be 4.3V.
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So I should get transformer close to 5V then so there is less heat? 6V for example?
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More or less, yes. There should be enough headroom to allow for normal line voltage variation, for transformer regulation, filter cap voltage droop, etc. Also depending on audio circuitry, voltage regulators may have some affect on sound. IOW, voltage regulator circuitry may not be fully decoupled from amplifier circuitry, rather they may interact in some way that affects sound. In that case, some regulators have been known to sound best with sufficient voltage drop and or sufficient load current. However, in this case it doesn't seem like you are being all that very picky about sound, so some of more subtle stuff may not applicable here.
Well I am picky about quality to an extent🙂 Im not building high end, but a decent system. I have separate supply for DAC only and it will be isolated from digital part. Now making PSU for digital only (as its terrible at the moment), think this approach is correct?
Also would you take this IC in my place? Go with SMPS instead?
Also would you take this IC in my place? Go with SMPS instead?
For myself I would probably keep RPi and SMPS away from my DAC. Both for conducted and radiated EMI/RFI noise reasons.
May I ask how you are isolating the dac, and how the whole system is clocked?
May I ask how you are isolating the dac, and how the whole system is clocked?
Yes, other end of case. Just i2s (iso7640) and i2c isolators. Clocked from dsp as it operate in Master mode only.
Okay. Sounds like DSP is I2S bus master for RPi GPIO bus? What about the dac clock, where is it? Is it also the reference clock for the DSP? Also, the isolators are between the dac and the DSP? Maybe it would be easier to see if there were a little signal flow diagram that also shows isolators and power supplies?
DSP is master, rest of devices are slaves,
DAC(slave)(separate power supply)<---- iso7640 isolation --- DSP(master)<------ raspberry pi(slave)
All digital - DSP, RPI, xmos from another power supply.
DAC(slave)(separate power supply)<---- iso7640 isolation --- DSP(master)<------ raspberry pi(slave)
All digital - DSP, RPI, xmos from another power supply.
So 0.1uF between SPDIF IN and GND, close to sharc?
Didn't try that but I will check board, maybe it was added already
Didn't try that but I will check board, maybe it was added already
No, between spdif input pin on sharc and output pin on device sending signal to sharc, not to ground.
Still not quite clear. Master and slave terminology usually refers to I2S bus clocks (LRCK, BCLK). The reference or master clock may be referred to as MCLK. For 96kHz sample rate operation, MCLK might be something like 12.288MHz or maybe a multiple of that, say, perhaps 24.576MHz. In that regard ESS dac chips are different than most because they have internal ASRC, which can allow them to run on more or less arbitrary MCLK frequencies (so long as MCLK is in the range specified in the ESS datasheet).
So, part of my question was about MCLK. Is there only one for the whole audio system and it is located on the DSP board?
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Regarding DC blocking for sharc chip SPDIF inputs, the following diagram can be found in: https://www.analog.com/media/en/technical-documentation/application-notes/ee.266.rev.2.08.07.pdf
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